I urval från Stockholms universitets publikationsdatabas

• A pan-European citizen science study shows population size, climate and land use are related to biased morph ratios in the heterostylous plant Primula veris

  2025. Tsipe Aavik (et al.). Journal of Ecology

  Artikel

  The distylous plant Primula veris has long served as a model species for studying heterostyly, that is the occurrence of multiple floral morphs within a population to ensure outcrossing. Habitat loss, reduced plant population sizes, and climate change have raised concerns about the impact of these factors on morph ratios and the related consequences on fitness of heterostylous species. We studied the deviation of floral morphs of P. veris from isoplethy (i.e. equal frequency) in response to plant population size, landscape context and climatic factors, based on a pan-European citizen science campaign involving observations from 28 countries. In addition, we examined the relative frequency of morphs to determine whether landscape and climatic factors disrupt morph frequencies or whether a specific morph has an advantage over the other. Theory predicts equal frequencies of short-styled S-morphs and long-styled L-morphs in populations at equilibrium. However, data from >3000 populations showed a substantial morph deviation from isoplethy and a significant excess of S-morphs (9% higher compared to L-morphs). Deviation of morph frequency from equilibrium was substantially stronger in smaller populations and was not affected by morph identity. Higher summer precipitation and land use intensity were associated with an increased prevalence of S-morphs. Five populations containing individuals exhibiting short homostyle phenotypes (with the style and anthers in low positions) were found. Genotyping of the individuals at CYP734A50 gene of the S locus, which determines the length of the style and the position of anthers of P. veris, revealed no mutations in this region. Our results based on an unprecedented geographic sampling suggest that changes in land use and climate may be responsible for non-equilibrium morph frequencies. This large-scale citizen science initiative sets foundations for future studies to clarify whether the unexpected excess of S-morphs is due to partial intra-morph compatibility, disruption of heterostyly or survival advantage of S-morphs. Synthesis. Human-induced environmental change may affect biodiversity indirectly through altering reproductive traits, which can also lead to reduced fitness and genetic diversity. Further research should consider the possible role of pollinators in mediating the ecological and evolutionary consequences of recent landscape and climatic shifts on plant reproductive traits.

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• Contrasting responses of bats and macro-moths to structural complexity in forest borders

  2025. Heather Wood, Adam Kimberley, Sara Cousins. Forest Ecology and Management 578

  Artikel

  Habitat fragmentation increases the proportion of forest borders in the landscape and many forest borders lose their structural complexity due to modern forestry practices. However, remnants of structurally complex deciduous forests can remain as ecotones between plantations and agricultural fields. In this study we used terrestrial laser scanning to measure structural complexity of different forest borders, measured microclimate, and surveyed bats and macro-moths to understand how these taxa are affected. Our aim is to disentangle the main drivers, direct or indirect, that influence bat and moth assemblages. We studied 79 forest borders, and surrounding landscapes and compared them with adjacent agricultural fields and coniferous plantations. Overall, we found less bat activity and lower macro-moth diversity in simple compared to complex borders. Using structural equation modelling, we show the contrasting responses of forest-specialist bats and moths to structural complexity; with bats responding positively and moths negatively. We found similar divergent results in relation to understorey openness; with increasing forest-specialist bat activity but a lower diversity of forest-specialist moths in more open borders. Understorey vegetation also appears to regulate microclimate with more open borders being warmer and less humid. This has a potential knock-on effect for bats as they favoured borders that were warmer and more humid. Surrounding land-cover was more important than structural complexity for generalist species; with increasing generalist bat activity due to a higher proportion of local deciduous forest cover and increasing generalist moth diversity in landscapes with more forest borders. Overall, these complex relationships between forest structure, microclimate and landscape factors, coupled with divergent responses of both taxa highlight their diverse ecological needs. Therefore, we highlight the importance of managing forest borders to retain complexity and connectivity within multifunctional landscapes.

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• Experimental drought and soil amendments affect grassland above- and belowground vegetation but not soil carbon stocks

  2025. Daniela Guasconi (et al.). SOIL 11 (1), 233-246

  Artikel

  Soils are the largest terrestrial carbon (C) pool on the planet, and targeted grassland management has the potential to increase grassland C sequestration. Appropriate land management strategies, such as organic matter addition, can increase soil C stocks and improve grasslands' resilience to drought by improving soil water retention and infiltration. However, soil carbon dynamics are closely tied to vegetation responses to management and climatic changes, which affect roots and shoots differently. This study presents findings from a 3-year field experiment on two Swedish grasslands that assessed the impact of compost amendment and experimental drought on plant biomass and soil C to a depth of 45 cm. Aboveground biomass and soil C content (% C) increased compared with untreated controls in compost-amended plots; however, because bulk density decreased, there was no significant effect on soil C stocks. Experimental drought did not significantly reduce plant biomass compared to control plots, but it stunted the increase in aboveground biomass in compost-treated plots and led to changes in root traits. These results highlight the complexity of ecosystem C dynamics and the importance of considering multiple biotic and abiotic factors across spatial scales when developing land management strategies to enhance C sequestration.

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• Global impoverishment of natural vegetation revealed by dark diversity

  2025. Meelis Pärtel (et al.). Nature

  Artikel

  Anthropogenic biodiversity decline threatens the functioning of ecosystems and the many benefits they provide to humanity. As well as causing species losses in directly affected locations, human influence might also reduce biodiversity in relatively unmodified vegetation if far-reaching anthropogenic effects trigger local extinctions and hinder recolonization. Here we show that local plant diversity is globally negatively related to the level of anthropogenic activity in the surrounding region. Impoverishment of natural vegetation was evident only when we considered community completeness: the proportion of all suitable species in the region that are present at a site. To estimate community completeness, we compared the number of recorded species with the dark diversity—ecologically suitable species that are absent from a site but present in the surrounding region2. In the sampled regions with a minimal human footprint index, an average of 35% of suitable plant species were present locally, compared with less than 20% in highly affected regions. Besides having the potential to uncover overlooked threats to biodiversity, dark diversity also provides guidance for nature conservation. Species in the dark diversity remain regionally present, and their local populations might be restored through measures that improve connectivity between natural vegetation fragments and reduce threats to population persistence.

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• The effects of climate change on boreal plant-pollinator interactions are largely neglected by science

  2025. Joan Díaz-Calafat (et al.). Basic and Applied Ecology 84, 1-13

  Artikel

  The boreal forest, one of the world's largest terrestrial biomes, is currently experiencing rapid climate-driven changes. This review synthesizes the limited research available on climate-change impacts on boreal plant-pollinator systems, revealing several knowledge gaps and shedding light on the vulnerabilities of boreal ecosystems. Using four complementary Web of Science searches, we found 5198 articles, of which only 11 were relevant. Our findings reveal that research on boreal plant-pollinator interactions is limited to date, as is our understanding of the insect fauna and pollination systems in the boreal region. Existing research often focuses on conspicuous plants, neglecting many other ecologically significant species. In addition, current studies often lack detailed data on pollinator species, which restricts our capacity to assess the vulnerability of specific plant-pollinator interactions to climate change. For example, most articles use plant reproductive success as a proxy for pollinator effectiveness without considering pollinator identity. This approach successfully assesses overall plant fitness, but overlooks changes to pollinator communities, such as those resulting from thermophilization, that may be relevant to projecting climate-change impacts. Moreover, pollinator taxon seems to affect the responses of plant reproduction to warming, with fly-pollinated plants appearing to be more resilient to temperature changes than bee-pollinated plants. Future research should prioritize foundational plant species and key pollinators, including flies, which are crucial to boreal pollination ecology. Understanding species-specific responses to warming is equally important for identifying which species and interactions may be most vulnerable to climate change. Studies should also examine the role of forest microclimates, as they may buffer boreal regions during broader climatic shifts, helping to mitigate the impacts of warming on these ecosystems. Addressing these gaps is essential for predicting climate impacts on boreal biodiversity and for informing conservation strategies that support biodiversity and benefit human communities reliant on boreal ecosystem services.

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• Variable time lags in genetic response of three temperate forest herbs to 70 years of agricultural landscape change

  2025. Siyu Huang (et al.). Landscape Ecology 40 (4)

  Artikel

  Context: Agriculture-driven land-use changes over the past decades have not only reduced the amount of habitat for species but also influenced the genetic exchange among the remaining fragmented populations. Many recent studies have found a delayed response in population genetic diversity and differentiation of species in fragmented habitats to past landscape disturbances, a so-called time lag. However, the specific role of species’ individual reproductive traits and the population genetic measures used remain poorly understood. Objectives: We examined the impact of past and current agricultural landscape composition in temperate Europe on the population genetic structure of three long-lived, slow-colonizing forest herb species – Anemone nemorosa, Oxalis acetosella and Polygonatum multiflorum, which vary in their reproductive traits. Methods: We considered four time points in history (mid-1900s, 1985, 2000 and 2017) to identify the potentially different length of time that is needed by each species to respond to landscape change. We also explored the impact of using different genetic measures in quantifying the time lags. Results: Our findings show that despite substantial landscape alterations about 70 years ago, the mid-1900s landscape composition was not reflected in the current genetic diversity and differentiation of the three species. This indicates a possible unexpected quick genetic adjustment of these species. Nevertheless, by combining the signals of multiple genetic measures, we found that O. acetosella, which reaches sexual maturity earlier than the other two species and is self-compatible, showed signs of faster genetic adjustment to these landscape changes. In contrast, A. nemorosa and P. multiflorum, which take longer to reach sexual maturity, might exhibit longer time lags that were beyond this study’s time frame. Conclusions: This study underscores the importance of considering the species’ reproductive traits and especially the role of temporal scales of different genetic measures when investigating the impact of landscape history on current population genetic structures.

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• Effect of green infrastructure on restoration of pollination networks and plant performance in semi-natural dry grasslands across Europe

  2024. Anna Traveset (et al.). Journal of Applied Ecology 61 (5), 1015-1028

  Artikel

  1. Agricultural intensification, afforestation and land abandonment are major drivers of biodiversity loss in semi-natural grasslands across Europe. Reversing these losses requires the reinstatement of plant–animal interactions such as pollination. Here we assessed the differences in species composition and patterns of plant-pollinator interactions in ancient and restored grasslands and how these patterns are influenced by landscape connectivity, across three European regions (Belgium, Germany and Sweden).
  2. We evaluated the differences in pollinator community assemblage, abundance and interaction network structure between 24 ancient and restored grasslands. We then assessed the effect of surrounding landscape functional connectivity (i.e. green infrastructure, GI) on these variables and tested possible consequences on the reproduction of two model plants, Lotus corniculatus and Salvia pratensis.
  3. Neither pollinator richness nor species composition differed between ancient and restored grasslands. A high turnover of interactions across grasslands was detected but was mainly due to replacement of pollinator and plant species. The impact of grassland restoration was consistent across various pollinator functional groups, whereas the surrounding GI had differential effects. Notably, bees, butterflies, beetles, and dipterans (excluding hoverflies) exhibited the most significant responses to GI variations. Interestingly, networks in restored grasslands were more specialised (i.e. less functionally redundant) than in ancient ones and also showed a higher number of insect visits to habitat-generalist plant species. Landscape connectivity had a similar effect, with habitat-specialist plant species receiving fewer visits at higher GI values.
  4. Fruit set in S. pratensis and L. corniculatus was unaffected by grassland type or GI. However, the fruit set in the specialist S. pratensis increased with the number of pollinator visits, indicating a positive correlation between pollinator activity and reproductive success in this particular species.
  5. Synthesis and applications. Our findings provide evidence of the necessity to enhance ecosystem functions while avoiding biotic homogenisation. Restoration programs should aim at increasing landscape connectivity which influences plant communities, pollinator assemblages and their interaction patterns. To avoid generalist species taking over from specialists in restored grasslands, we suggest reinforcing the presence of specialist species in the latter, for instance by means of introductions, as well as increasing the connectivity to source populations.

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• Grassland species colonization of a restored grassland on a former forest varies in short-term success but is facilitated by greater functional connectivity

  2024. Rozália E. Kapás, Adam Kimberley, Sara A. O. Cousins. Nordic Journal of Botany 2024 (4)

  Artikel

  In recent years, restoration on former grassland sites has been widely encouraged globally, aiming to address the historical loss of 90% of ancient species-rich grasslands, and to mitigate the associated threat to grassland biodiversity. The objective of our study was to investigate on a small-scale how plant species spontaneously colonize restored grasslands. We inventoried 275 permanent plots twice (in 2019 and 2021) in a restored grassland, following the removal of a conifer plantation. Species richness and vegetation cover in surveyed plots were dependent on grazing activity and distance to adjacent grassland. Plant species associated with forest habitats declined, while the occurrence of generalist species together with a few grassland specialists generally increased. However, not all grassland specialists gained occurrence and the colonization pattern was not consistent over time, possibly due to the lack of continuous seed arrival and low livestock activity and hence lack of disturbance. These results suggest that successful colonization of plant species benefits from links to species-rich sites adjacent to the restoration target, with spatial dispersal and improved conditions for species establishment being key to species occurrence. Both dispersal and establishment potential are likely facilitated through the presence of grazing livestock with access to both species-rich grasslands and restoration targets. However, the shift towards a more typical grassland community takes place gradually, with vulnerable populations of early colonizing grassland species prone to local extinction in short-term. As a result, continued functional connectivity provided by grazing animals is necessary to improve the diversity of the restored site and ensure the establishment of grassland specialists and to maintain the plant community composition.

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• Habitat loss and isolation threaten specialist flora in Baltic coastal meadows

  2024. Lukas Rimondini, Adam Kimberley, Sara Cousins. Journal of Vegetation Science 35 (4)

  Artikel

  Questions: Baltic coastal meadows are ecologically unique habitats that have been severely impacted by habitat loss and environmental change. To determine the effects of habitat loss and isolation on their plant communities, we analysed the relationships between species richness and habitat size and amount. Because coastal meadows host species with a vast array of traits, we expected responses to vary between species groups. Location: Swedish Baltic coast. Methods: We inventoried the presence of vascular plant species in twenty-eight 1-m2 plots placed along edaphically defined transects in fifteen coastal meadows. We determined the richness of three species groups: all species, halophytes and inland grassland specialists. We then mapped the habitat for coastal grassland plants using GIS overlay analysis. Using this habitat map, we calculated two variables: “habitat size” and “habitat amount”. We tested correlations between species richness measures and habitat variables, as well as determining the distribution of species traits within meadows. Results: We recorded 174 plant species, of which 6 were halophytes and 35 were inland grassland specialists. Species traits coincided with edaphic sea-to-land gradients. Halophyte and inland grassland specialist richness were significantly correlated with both habitat variables (r = 0.52–0.71). No correlations were found with total species richness. Our habitat map showed that there are 8,900 ha of managed Baltic coastal meadow left in Sweden, mostly in the south. Conclusions: Species traits and distribution play a major role in determining persistence in the face of habitat loss and environmental change. This is especially true for some halophyte populations, which are more susceptible to habitat size and isolation because of their specialisation. Furthermore, they risk being squeezed between the dual threats of encroaching succession and sea-level rise. Preventing habitat loss, restoring meadows and increasing connectivity is crucial for the persistence of specialist plant species.

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• Nutrient-demanding and thermophilous plants dominate urban forest-edge vegetation across temperate Europe

  2024. Karen De Pauw (et al.). Journal of Vegetation Science 35 (1)

  Artikel

  Questions

  Forests are highly fragmented across the globe. For urban forests in particular, fragmentation increases the exposure to local warming caused by the urban heat island (UHI) effect. We here aim to quantify edge effects on herbaceous understorey vegetation in urban forests, and test whether these effects interact with forest structural complexity.

  Location

  We set up a pan-European study at the continental scale including six urban forests in Zurich, Paris, Katowice, Brussels, Bremen, and Stockholm.

  Methods

  We recorded understorey plant communities from the edge towards the interior of urban forests. Within each urban forest, we studied edge-to-interior gradients in paired stands with differing forest structural complexity. Community composition was analysed based on species specialism, life form, light, nutrient, acidity and disturbance indicator values and species' thermal niches.

  Results

  We found that herbaceous communities at urban forest edges supported more generalists and forbs but fewer ferns than in forests' interiors. A buffered summer microclimate proved crucial for the presence of fern species. The edge communities contained more thermophilous, disturbance-tolerant, nutrient-demanding and basiphilous plant species, a pattern strongly confirmed by corresponding edge-to-interior gradients in microclimate, soil and light conditions in the understorey. Additionally, plots with a lower canopy cover and higher light availability supported higher numbers of both generalists and forest specialists. Even though no significant interactions were found between the edge distance and forest structural complexity, opposing additive effects indicated that a dense canopy can be used to buffer negative edge effects.

  Conclusion

  The urban environment poses a multifaceted filter on understorey plant communities which contributes to significant differences in community composition between urban forest edges and interiors. For urban biodiversity conservation and the buffering of edge effects, it will be key to maintain dense canopies near urban forest edges. The urban environment poses a multifaceted filter on understorey plant communities which contributes to significant differences in community composition between urban forest edges and interiors. For urban biodiversity conservation and the buffering of edge effects, it will be key to maintain dense canopies near urban forest edges.image

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• Patterns of local plant diversity and community saturation in deciduous forests in Europe

  2024. Jolina Paulssen (et al.). Journal of Vegetation Science 35 (6)

  Artikel

  Questions How do local forest conditions and characteristics at the forest patch - scale and landscape - scale affect plot-scale plant diversity in Europe? Do these patterns vary between forest specialists and generalists? Do community saturation patterns differ between forests varying in their surrounding landscape type?

  Location: Deciduous forests sampled along a European gradient from southwest to northeast comprising eight regions in five countries (France, Belgium, Germany, Sweden, Estonia).

  Methods: We examined the effects of local conditions assessed by means of Ellenberg indicator values (soil moisture, soil nitrogen, soil pH, light availability), patch-scale characteristics (patch-scale plant diversity, forest patch age, forest patch size) and a landscape-scale variable (representing low and high connectivity of forest patches) on plot-scale plant diversity, separately for forest specialist and generalist species. Additionally, we ran regression models to examine community saturation patterns.

  Results: We found patterns of niche partitioning among forest specialists and generalists. Low light availability and medium soil moisture favored forest specialists, while generalists were mostly present at higher light availability and medium and high soil moisture. In general, we found the highest plot-scale diversity at medium soil pH. Patch-scale diversity showed a positive impact on plot-scale diversity and plots in the high-connectivity landscape had a higher diversity than plots in the low-connectivity landscape. Further, we observed a high degree of community saturation in both landscape types.

  Conclusion: The positive impact of a high connectivity of forest patches on local plant diversity emphasizes the importance of small semi-natural habitats like tree lines, unused field margins and hedgerows to enhance the potential dispersal of forest plants across agricultural landscapes. Community saturation patterns revealed the increasing relevance of local conditions and processes for plot-scale diversity when patch-scale diversity increases.

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• The role of seed rain, seed bank, and clonal growth in plant colonization of ancient and restored grasslands

  2024. Rozália E. Kapás, Adam Kimberley, Sara Cousins. Ecology and Evolution 14 (6)

  Artikel

  Understanding the establishment of plant species is important to inform management of restored grasslands and to preserve biodiversity in ancient grasslands. In grassland communities, plant species can establish from seeds arriving via spatial dispersal, from seeds in the soil seed bank or through vegetative spread from nearby source individuals. However, this colonization potential and the likelihood of species establishment can vary in grasslands with different land-use history. We investigated the relative importance of local species recruitment sources, such as dispersal in space and time and species presence in adjacent grasslands, in determining establishment of plant species in eight grasslands with different land-use history (paired ancient grasslands continuously managed as pasture vs. restored grasslands on former forest). At each grassland, we established plots (0.25 m2) to monitor seedling emergence from seed dispersal, seed bank, and recorded clonal growth over two growing periods. We found that the likelihood of species establishment was highest from local seed rain, and that species present in the local species pool were more able to germinate and establish in both type of grasslands. Species from the seed bank and clonal growth contributed to a lesser extent to species establishment, but represented a greater proportion of the recolonization and regeneration of species in ancient grasslands. These results demonstrate that surrounding grasslands serve as a source for colonizing species and that dispersal from the adjacent grasslands is the key process in regeneration and colonization of plants. These results imply that the recovery of grasslands depends heavily upon to links to species source in grasslands, especially in restored grasslands. Therefore, management plans should incorporate rotational livestock grazing and larger networks of grassland in restoration efforts, which will enable to desirable species to establish and persist in grasslands.

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• The urban heat island accelerates litter decomposition through microclimatic warming in temperate urban forests

  2024. Karen De Pauw (et al.). Urban Ecosystems 27, 909-926

  Artikel

  Forests worldwide are experiencing fragmentation, with especially important consequences for ecosystems bordering urbanized areas. Urban forests are exposed to local warming due to the urban heat island which affects their biodiversity and ecosystem functioning. A key ecosystem function affecting carbon and nutrient cycling in forests is litter decomposition, a process driven by the local microclimate. Thus, our aim was to clarify the impact of the urban heat island on litter decomposition in urban forests. We studied soil microclimate and litter decomposition in six urban forests across Europe and along local gradients from the urban forest edge to the interior. To quantify decomposition independent from local forest composition and litter quality, we used standardized green tea and rooibos tea litterbags. We determined the role of the soil microclimate and other environmental drivers for litter decomposition. Secondly, we assessed effects of edge proximity and landscape context on the soil microclimate. Soil characteristics were only driving green tea and not rooibos tea decomposition. On the contrary, higher soil temperatures resulted in faster rates of litter decomposition for both green and rooibos tea and were related to the proximity to the forest edge and the proportion of built-up area in the landscape. Via structural equation modelling we detected cascading effects of the urban heat island on litter decomposition. Such changes in litter decomposition have the potential to alter the soil food web, nutrient cycling and carbon drawdown in urban forests, and could result in significant interactions between urbanisation and ongoing climate change.

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• Trade-offs in biodiversity and ecosystem services between edges and interiors in European forests

  2024. Thomas Vanneste (et al.). Nature Ecology & Evolution 8, 880-887

  Artikel

  Forest biodiversity and ecosystem services are hitherto predominantly quantified in forest interiors, well away from edges. However, these edges also represent a substantial proportion of the global forest cover. Here we quantified plant biodiversity and ecosystem service indicators in 225 plots along forest edge-to-interior transects across Europe. We found strong trade-offs: phylogenetic diversity (evolutionary measure of biodiversity), proportion of forest specialists, decomposition and heatwave buffering increased towards the interior, whereas species richness, nectar production potential, stemwood biomass and tree regeneration decreased. These trade-offs were mainly driven by edge-to-interior structural differences. As fragmentation continues, recognizing the role of forest edges is crucial for integrating biodiversity and ecosystem service considerations into sustainable forest management and policy.

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• Trait–micro-environment relationships of forest herb communities across Europe

  2024. Sanne Govaert (et al.). Global Ecology and Biogeography 33 (2), 286-302

  Artikel

  Aim: The microclimate and light conditions on the forest floor are strongly modified by tree canopies. Therefore, we need to better consider the micro-environment when quantifying trait–environment relationships for forest understorey plants. Here, we quantify relationships between micro-environmental conditions and plant functional traits at the community level, including intraspecific trait variation, and their relationship with microclimate air temperature, light and soil properties.

  Location: Deciduous temperate forests across Europe.

  Time period: 2018.

  Major taxa studied: Herbaceous vegetation.

  Methods: We sampled 225 plots across 15 regions along four complementary gradients capturing both macro- and microclimatic conditions including latitude, elevation, forest management and distance to forest edges. We related the community-weighted mean of five plant functional traits (plant height, specific leaf area [SLA], plant carbon [C], plant nitrogen [N] and plant C:N ratio) across 150 vascular plant species to variation in local microclimate air temperature, light and soil properties. We tested the effect of accounting for intraspecific variation in trait–environment relationships and performed variation partitioning to identify major drivers of trait variation.

  Results: Microclimate temperature, light availability and soil properties were all important predictors of community-weighted mean functional traits. When light availability and variation in temperature were higher, the herb community often consisted of taller plants with a higher C:N ratio. In more productive environments (e.g. with high soil nitrogen availability), the community was dominated by individuals with resource-acquisitive traits: high SLA and N but low C:N. Including intraspecific trait variation increased the strength of the trait–micro-environment relationship, and increased the importance of light availability.

  Main conclusions: The trait–environment relationships were much stronger when the micro-environment and intraspecific trait variation were considered. By locally steering light availability and temperature, forest managers can potentially impact the functional signature of the forest herb-layer community.

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• Using warming tolerances to predict understory plant responses to climate change

  2024. Liping Wei (et al.). Global Change Biology 30 (1)

  Artikel

  Climate change is pushing species towards and potentially beyond their critical thermal limits. The extent to which species can cope with temperatures exceeding their critical thermal limits is still uncertain. To better assess species' responses to warming, we compute the warming tolerance (ΔT_niche) as a thermal vulnerability index, using species' upper thermal limits (the temperature at the warm limit of their distribution range) minus the local habitat temperature actually experienced at a given location. This metric is useful to predict how much more warming species can tolerate before negative impacts are expected to occur. Here we set up a cross-continental transplant experiment involving five regions distributed along a latitudinal gradient across Europe (43° N–61° N). Transplant sites were located in dense and open forests stands, and at forest edges and in interiors. We estimated the warming tolerance for 12 understory plant species common in European temperate forests. During 3 years, we examined the effects of the warming tolerance of each species across all transplanted locations on local plant performance, in terms of survival, height, ground cover, flowering probabilities and flower number. We found that the warming tolerance (ΔT_niche) of the 12 studied understory species was significantly different across Europe and varied by up to 8°C. In general, ΔT_niche were smaller (less positive) towards the forest edge and in open stands. Plant performance (growth and reproduction) increased with increasing ΔT_niche across all 12 species. Our study demonstrated that ΔT_niche of understory plant species varied with macroclimatic differences among regions across Europe, as well as in response to forest microclimates, albeit to a lesser extent. Our findings support the hypothesis that plant performance across species decreases in terms of growth and reproduction as local temperature conditions reach or exceed the warm limit of the focal species.

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• Variation in insect herbivory across an urbanization gradient: The role of abiotic factors and leaf secondary metabolites

  2024. Xoaquín Moreira (et al.). Plant physiology and biochemistry (Paris) 215

  Artikel

  Urbanization impacts plant-herbivore interactions, which are crucial for ecosystem functions such as carbon sequestration and nutrient cycling. While some studies have reported reductions in insect herbivory in urban areas (relative to rural or natural forests), this trend is not consistent and the underlying causes for such variation remain unclear. We conducted a continental-scale study on insect herbivory along urbanization gradients for three European tree species: Quercus robur, Tilia cordata, and Fraxinus excelsior, and further investigated their biotic and abiotic correlates to get at mechanisms. To this end, we quantified insect leaf herbivory and foliar secondary metabolites (phenolics, terpenoids, alkaloids) for 176 trees across eight European cities. Additionally, we collected data on microclimate (air temperature) and soil characteristics (pH, carbon, nutrients) to test for abiotic correlates of urbanization effects directly or indirectly (through changes in plant secondary chemistry) linked to herbivory. Our results showed that urbanization was negatively associated with herbivory for Q. robur and F. excelsior, but not for T. cordata. In addition, urbanization was positively associated with secondary metabolite concentrations, but only for Q. robur. Urbanization was positively associated with air temperature for Q. robur and F. excelsior, and negatively with soil nutrients (magnesium) in the case of F. excelsior, but these abiotic variables were not associated with herbivory. Contrary to expectations, we found no evidence for indirect effects of abiotic factors via plant defences on herbivory for either Q. robur or F. excelsior. Additional biotic or abiotic drivers must therefore be accounted for to explain observed urbanization gradients in herbivory and their interspecific variation.

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• Could green infrastructure supplement ecosystem service provision from semi-natural grasslands?

  2023. Danny A. P. Hooftman (et al.). Journal of Environmental Management 328

  Artikel

  Ancient semi-natural grasslands in Europe are important for ecosystem service (ES) provision. Often, the surrounding matrix contains ‘Grassland Green Infrastructure’ (GGI) that contain grassland species which have the potential to supplement grassland ES provision across the landscape. Here we investigate the potential for GGI to deliver a set of complementary ES, driven by plant composition.We surveyed 36 landscapes across three European countries comprising core grasslands and their surrounding GGI. We calculated community-level values of plant species characteristics to provide indicators for four ES: nature conservation value, pollination, carbon storage and aesthetic appeal.Inferred ES delivery for GGI was substantially lower than in core grasslands for conservation, pollination and aesthetic appeal indicators, but not for carbon storage. These differences were driven by the GGI having 17% fewer plant species, and compositional differences, with 61% of species unique to the core grasslands. In addition, connectivity to the core, the amount of GGI and inferred seed dispersal distances by livestock, were strongly positively correlated with conservation value, pollination and aesthetic indicators. All ES indicators showed similar responses to the GGI spatial structure and distance to the core, suggesting robust effects of these drivers on ES. We projected that improved landscape-wide delivery of nature conservation value and pollination could be achieved through targeted GGI management. Reductions in the distances seeds would need to disperse, more GGI, along with a diversification of the GGI elements, were predicted to enhance service credits.We conclude that for vegetation-related ES, species surveys can be employed to assess potential ES delivery. Creating and enhancing GGI is a useful landscape management strategy to supplement the ES delivered by ancient grasslands.

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• Experimental warming outside the growing season and exclusion of grazing has a mild effect on upland grassland plant communities in the short term

  2023. Nina Roth (et al.). Plant Ecology & Diversity 16 (5-6), 189-201

  Artikel

  Background: Winters are expected to warm more than summers in central and northern Europe, with largely unknown effects on grassland plant communities.

  Aims: By studying the interactions between winter warming and summer grazing, we aimed to disentangle their effects and give recommendations for future grassland management.

  Methods: Our study area Upper Teesdale, England has winter temperatures close to 0°C and a well-studied vegetation, known for its arctic-alpine species growing at their climatic warm range limits. We set up a winter warming experiment using open top chambers (ca. +0.5°C) from mid-September until mid-May 2019 to 2022 and excluded sheep grazing during summer in a fully factorial design.

  Results: Graminoid biomass increased, and bryophyte biomass decreased with winter warming. There was little to no evidence that winter warming affected any of the other plant response variables we measured, neither did grazing nor the interaction between winter warming and grazing.

  Conclusions: Our experiment was relatively short in duration and treatments were realistic in magnitude, therefore the plant communities responded only slightly. Nevertheless, our data suggest a change towards more dominant vascular species and less bryophytes with winter warming, which might lead to lasting changes in the plant communities in the longer-term if not buffered by suitable grazing management.

  Läs mer om Experimental warming outside the growing season and exclusion of grazing has a mild effect on upland grassland plant communities in the short term

• Floral resources in Swedish grasslands remain relatively stable under an experimental drought and are enhanced by soil amendments if regularly mown

  2023. Nina Roth (et al.). Ecological Solutions and Evidence 4 (2)

  Artikel

  1. One of the main reasons why insect pollinators are declining is a lack of floral resources. In agricultural landscapes, remaining seminatural grasslands play a key role for providing such resources. However, droughts pose an increasing threat to the abundance and continuity of flowers. Soil amendments are a novel management tool for Swedish grasslands aiming to increase carbon sequestration and soil water holding capacity. In this study, we examined how drought is affecting floral resources (i.e. floral units, nectar quantity and nectar continuity) in grasslands with different mowing regimes, and if soil amendments could mitigate potential negative drought effects.
  2. In summer 2019, we set up an experiment combining rain-out shelters (‘drought’), soil amendments (‘compost’) and different mowing regimes (‘mown’ vs. ‘abandoned’) in four extensively managed Swedish grasslands (48 plots, size 2 m²). Between May and August 2021, we counted the floral units nine times in each plot. We derived values for the nectar sugar production per floral unit from an existing database.
  3. We observed a decrease in floral units under drought in the mown, but not in the abandoned plots. Nectar quantity and continuity over the season were not significantly affected by drought across both mowing regimes—in the abandoned plots the nectar provision even extended slightly in duration (towards late summer). The compost treatment had positive effects on the floral units, nectar quantity and continuity (extending it towards early summer) in the mown, but not in the abandoned plots. The plant species in our study reacted differently to the treatments. Most of the nectar was provided by only few species (mainly Lathyrus pratensis, Vicia cracca and Anthriscus sylvestris).
  4. The results are species specific, thus other plant communities might respond differently. However, our experiment shows that nectar provision (based on database values) in grasslands with a native plant community and natural soil conditions remains relatively stable under drought. We also found that soil amendments increase floral resources in managed grasslands.

  Läs mer om Floral resources in Swedish grasslands remain relatively stable under an experimental drought and are enhanced by soil amendments if regularly mown

• From broadleaves to conifers: The effect of tree composition and density on understory microclimate across latitudes

  2023. Joan Díaz-Calafat (et al.). Agricultural and Forest Meteorology 341

  Artikel

  Forest canopies buffer the macroclimate and thus play an important role in mitigating climate-warming impacts on forest ecosystems. Despite the importance of the tree layer for understory microclimate buffering, our knowledge about the effects of forest structure, composition and their interactions with macroclimate is limited, especially in mixtures of conifers and broadleaves. Here we studied five mixed forest stands along a 1800 km latitudinal gradient covering a 7°C span in mean annual temperature. In each of these forests we established 40 plots (200 in total), in which air and soil temperatures were measured continuously for at least one year. The plots were located across gradients of forest density and broadleaved proportions (i.e. from open to closed canopies, and from 100% conifer to 100% broadleaved tree dominance). Air minimum, mean and maximum temperature offsets (i.e. difference between macroclimate and microclimate) and soil mean temperature offsets were calculated for the coldest and warmest months. Forest structure, and especially forest density, was the key determinant of understory temperatures. However, the absolute and relative importance of the proportion of broadleaves and forest density differed largely between response variables. Forest density ranged from being independent of, to interacting with, tree species composition. The effect of these two variables was independent of the macroclimate along our latitudinal gradient. Temperature, precipitation, snow depth and wind outside forests affected understory temperature buffering. Finally, we found that the scale at which the overstory affects soil microclimate approximated 6-7 m, whereas for air microclimate this was at least 10 m. These findings have implications for biodiversity conservation and forest management in a changing climate, as they facilitate the projection of understory temperatures in scenarios where both forest structure and macroclimate are dynamic. This is especially relevant given the global importance of ongoing forest conversion from conifers to broadleaves, and vice versa.

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• Microclimate and forest density drive plant population dynamics under climate change

  2023. Pieter Sanczuk (et al.). Nature Climate Change 13 (8), 840-847

  Artikel

  Macroclimatic changes are impacting ecosystems worldwide. However, a large portion of terrestrial species live under conditions where impacts of macroclimate change are buffered, such as in the shade of trees, and how this buffering impacts future below-canopy biodiversity redistributions at the continental scale is unknown. Here we show that shady forest floors due to dense tree canopies mitigate severe warming impacts on forest biodiversity, while canopy opening amplifies macroclimate change impacts. A cross-continental transplant experiment in five contrasting biogeographical areas combined with experimental heating and irradiation treatments was used to parametize 25-m resolution mechanistic demographic distribution models and project the current and future distributions of 12 common understorey plant species, considering the effects of forest microclimate and forest cover density. These results highlight microclimates and forest density as powerful tools for forest managers and policymakers to shelter forest biodiversity from climate change.

  The impacts of microclimate on future plant population dynamics are poorly understood. The authors use large-scale transplant climate change experiments to show the contribution of forest microclimates to population dynamics and project the distributions of 12 common understorey plants.

  Läs mer om Microclimate and forest density drive plant population dynamics under climate change

• Spatial and temporal variability in soil and vegetation carbon dynamics under experimental drought and soil amendments

  2023. Daniela Guasconi (et al.).

  Artikel

  Soils are the largest carbon (C) pool on the planet, and grassland soils have a particularly large C sequestration potential. Appropriate land management strategies, such as organic matter additions, can improve soil health, increase soil C stocks, and increase grassland resilience to drought by improving soil moisture retention. However, soil C dynamics are deeply linked to vegetation response to changes in both management and climate, which may also be manifested differently in roots and shoots. This study presents findings from a three-year experiment that assessed the impact of a compost amendment and of reduced precipitation on soil and vegetation C pools. Compost addition increased aboveground biomass and soil C content (%C), but because bulk density decreased, there was no significant effect on soil C stocks. Drought decreased aboveground biomass, but did not significantly affect root biomass. Overall, the soil amendment shifted C allocation to aboveground plant organs, and drought to belowground organs. We also observed significant spatial and temporal variability in vegetation biomass and soil C over the study period. These results highlight the need to consider multiple biotic and abiotic factors driving ecosystem C dynamics across spatial scales when upscaling results from field trials.

  Läs mer om Spatial and temporal variability in soil and vegetation carbon dynamics under experimental drought and soil amendments

• Urban forest microclimates across temperate Europe are shaped by deep edge effects and forest structure

  2023. Karen De Pauw (et al.). Agricultural and Forest Meteorology 341

  Artikel

  The urban heat island (UHI) causes strong warming of cities and their urban forests worldwide. Especially urban forest edges are strongly exposed to the UHI effect, which could impact urban forest biodiversity and functioning. However, it is not known to what extent the UHI effect alters edge-to-interior microclimatic gradients within urban forests and whether this depends on the forests' structure.Here we quantified gradients of air temperature, relative air humidity and vapour pressure deficits (VPD) along urban forest edge-to-interior transects with contrasting stand structures in six major cities across Europe. We performed continuous hourly microclimate measurements for two consecutive years and analysed the magnitude and depth of edge effects, as well as forest structural drivers of microclimatic variation.Compared to edge studies in rural temperate forests, we found that edge effects reached deeper into urban forests, at least up to 50 m. Throughout the year, urban forest edges were warmer and drier compared to forest interiors, with the largest differences occurring during summer and daytime. Not only maximum, but also mean and minimum temperatures were higher at the urban forest edge up to large edge distances (at least 85 m). Denser forests with a higher plant area index buffered high air temperatures and VPDs from spring to autumn.We conclude that urban forest edges are unique ecotones with specific microclimates shaped by the UHI effect. Both forest edges and interiors showed increased buffering capacities with higher forest canopy density. We advocate for the conservation and expansion of urban forests which can buffer increasingly frequent and intense climate extremes. To this end, urban forest managers are encouraged to aim for multi-layered dense forest canopies and consider edge buffer zones of at least 50 m wide.

  Läs mer om Urban forest microclimates across temperate Europe are shaped by deep edge effects and forest structure

• Variability in bat morphology is influenced by temperature and forest cover and their interactions

  2023. Heather Wood, Sara Cousins. Ecology and Evolution 13 (1)

  Artikel

  Multiple climatic and landscape drivers have been linked to variations in bat body size and wing functional traits. Most previous studies used proxies rather than actual climate and land-use data, and their interactions are rarely explored. We investigate whether higher summer average temperatures are driving decreasing bat body size as predicted by Bergmann's rule or increasing appendage size as per Allen's rule. We also explore whether temperature or resource availability (namely forest cover) is responsible for changes in wing functional traits. Using land-use data from historical maps and national statistics combined with climatic data, we assessed the effect of temperature and resource availability on bat morphology. We used 464 museum specimens of three bat species (Eptesicus nilssonii, Pipistrellus pygmaeus, and Plecotus auritus), spanning 180 years, across a 1200 km latitudinal gradient. We found no evidence of higher summer average temperatures driving decreases in body size in bats. Jaw sizes of P. auritus and P. pygmaeus changed over time but in different directions. The geographical variation of forest cover was also related to differences in wing functional traits in two species. Crucially, there was a significant antagonistic interactive effect of forest and temperature on tip index in P. pygmaeus whereby above 14.5°C the relationship between forest and tip index actually reversed. This could indicate that higher temperatures promote more pointed wings, which may provide energetic benefits. Our results show the importance of including both climatic and land-use variables when assessing trends in bat morphology and exploring interactions. Encouragingly, all three species have shown an ability to adapt their body size and functional traits to different conditions, and it could demonstrate their potential to overcome future negative impacts of climate and land-use change. 

  Läs mer om Variability in bat morphology is influenced by temperature and forest cover and their interactions

• Vegetation, topography, and soil depth drive microbial community structure in two Swedish grasslands

  2023. Daniela Guasconi (et al.). FEMS Microbiology Ecology 99 (8)

  Artikel

  Soil microbial diversity and community composition are shaped by various factors linked to land management, topographic position,and vegetation. To study the effects of these drivers, we characterized fungal and bacterial communities from bulk soil at four soildepths ranging from the surface to below the rooting zone of two Swedish grasslands with differing land-use histories, each includingboth an upper and a lower catenary position. We hypothesized that differences in plant species richness and plant functional groupcomposition between the four study sites would drive the variation in soil microbial community composition and correlate withmicrobial diversity, and that microbial biomass and diversity would decrease with soil depth following a decline in resource availability.While vegetation was identified as the main driver of microbial community composition, the explained variation was significantlyhigher for bacteria than for fungi, and the communities differed more between grasslands than between catenary positions. Microbialbiomass derived from DNA abundance decreased with depth, but diversity remained relatively stable, indicating diverse microbialcommunities even below the rooting zone. Finally, plant-microbial diversity correlations were significant only for specific plant andfungal functional groups, emphasizing the importance of functional interactions over general species richness

  Läs mer om Vegetation, topography, and soil depth drive microbial community structure in two Swedish grasslands

• Context matters: the landscape matrix determines the population genetic structure of temperate forest herbs across Europe

  2022. Tobias Naaf (et al.). Landscape Ecology 37 (5), 1365-1384

  Artikel

  Context Plant populations in agricultural landscapes are mostly fragmented and their functional connectivity often depends on seed and pollen dispersal by animals. However, little is known about how the interactions of seed and pollen dispersers with the agricultural matrix translate into gene flow among plant populations.

  Objectives We aimed to identify effects of the landscape structure on the genetic diversity within, and the genetic differentiation among, spatially isolated populations of three temperate forest herbs. We asked, whether different arable crops have different effects, and whether the orientation of linear landscape elements relative to the gene dispersal direction matters.

  Methods We analysed the species' population genetic structures in seven agricultural landscapes across temperate Europe using microsatellite markers. These were modelled as a function of landscape composition and configuration, which we quantified in buffer zones around, and in rectangular landscape strips between, plant populations.

  Results Landscape effects were diverse and often contrasting between species, reflecting their association with different pollen- or seed dispersal vectors. Differentiating crop types rather than lumping them together yielded higher proportions of explained variation. Some linear landscape elements had both a channelling and hampering effect on gene flow, depending on their orientation.

  Conclusions Landscape structure is a more important determinant of the species' population genetic structure than habitat loss and fragmentation per se. Landscape planning with the aim to enhance the functional connectivity among spatially isolated plant populations should consider that even species of the same ecological guild might show distinct responses to the landscape structure.

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• Forest understorey communities respond strongly to light in interaction with forest structure, but not to microclimate warming

  2022. Karen De Pauw (et al.). New Phytologist 233 (1), 219-235

  Artikel

  • Forests harbour large spatiotemporal heterogeneity in canopy structure. This variation drives the microclimate and light availability at the forest floor. So far, we do not know how light availability and sub-canopy temperature interactively mediate the impact of macroclimate warming on understorey communities.
  • We therefore assessed the functional response of understorey plant communities to warming and light addition in a full factorial experiment installed in temperate deciduous forests across Europe along natural microclimate, light and macroclimate gradients. Furthermore, we related these functional responses to the species’ life-history syndromes and thermal niches.
  • We found no significant community responses to the warming treatment. The light treatment, however, had a stronger impact on communities, mainly due to responses by fast-colonizing generalists and not by slow-colonizing forest specialists. The forest structure strongly mediated the response to light addition and also had a clear impact on functional traits and total plant cover.
  • The effects of short-term experimental warming were small and suggest a time-lag in the response of understorey species to climate change. Canopy disturbance, for instance due to drought, pests or logging, has a strong and immediate impact and particularly favours generalists in the understorey in structurally complex forests.

  Läs mer om Forest understorey communities respond strongly to light in interaction with forest structure, but not to microclimate warming

• Green infrastructure can promote plant functional connectivity in a grassland species around fragmented semi-natural grasslands in NW-Europe

  2022. Jan Plue (et al.). Ecography 2022 (10)

  Artikel

  Species may benefit from green infrastructure, i.e. the network of natural and anthropogenic habitat remnants in human-dominated landscapes, if it helps isolated populations in remaining habitat patches to be functionally connected. The importance of green infrastructure is therefore increasingly emphasized in conservation policy to counter biodiversity loss. However, there is limited evidence, particularly in plants, that green infrastructure promotes functional connectivity, i.e. supports the colonization of habitat patches across a landscape. We applied landscape genetics to test whether the green infrastructure supports structural and functional connectivity in the grassland perennial Galium verum, in 35 landscapes in Belgium, Germany and Sweden. We used multivariate genetic clustering techniques, nestedness analyses and conditional inference trees to examine landscape-scale patterns in genetic diversity and structure of plant populations in the green infrastructure surrounding semi-natural grasslands. Inferred functional connectivity explained genetic variation better than structural connectivity, yielding positive effects on genetic variation. The road verge network, a major structural component of the green infrastructure and its functional connectivity, most effectively explained genetic diversity and composition in G. verum. Galium verum ramets occupying the surrounding landscape proved to be genetic subsets of focal grassland populations, shaping a nested landscape population genetic structure with focal grasslands, particularly ancient ones, harbouring unique genetic diversity. This nested pattern weakened as road network density increased, suggesting road verge networks enable high landscape occupancy by increased habitat availability and facilitates gene flow into the surrounding landscape. Our study proposes that green infrastructure can promote functional connectivity, providing that a plant species can survive outside of core habitat patches. As this often excludes habitat specialist species, conservation practice and policy should primarily focus on ancient, managed semi-natural grasslands. These grasslands both harbour unique genetic diversity and act as primary gene and propagule sources for the surrounding landscape, highlighting their conservation value.

  Läs mer om Green infrastructure can promote plant functional connectivity in a grassland species around fragmented semi-natural grasslands in NW-Europe

• Initial oak regeneration responses to experimental warming along microclimatic and macroclimatic gradients

  2022. C. Meeussen (et al.). Plant Biology 24 (5), 745-757

  Artikel

  • Quercus spp. are one of the most important tree genera in temperate deciduous forests in terms of biodiversity, economic and cultural perspectives. However, natural regeneration of oaks, depending on specific environmental conditions, is still not sufficiently understood. Oak regeneration dynamics are impacted by climate change, but these climate impacts will depend on local forest management and light and temperature conditions.
  • Here, we studied germination, survival and seedling performance (i.e. aboveground biomass, height, root collar diameter and specific leaf area) of four oak species (Q. cerris, Q. ilex, Q. robur and Q. petraea). Acorns were sown across a wide latitudinal gradient, from Italy to Sweden, and across several microclimatic gradients located within and beyond the species’ natural ranges. Microclimatic gradients were applied in terms of forest structure, distance to the forest edge and experimental warming.
  • We found strong interactions between species and latitude, as well as between microclimate and latitude or species. The species thus reacted differently to local and regional changes in light and temperature ; in southern regions the temperate Q. robur and Q. petraea performed best in plots with a complex structure, whereas the Mediterranean Q. ilex and Q. cerris performed better in simply structured forests with a reduced microclimatic buffering capacity. The experimental warming treatment only enhanced height and aboveground biomass of Mediterranean species.
  • Our results show that local microclimatic gradients play a key role in the initial stages of oak regeneration; however, one needs to consider the species-specific responses to forest structure and the macroclimatic context.

  Läs mer om Initial oak regeneration responses to experimental warming along microclimatic and macroclimatic gradients

• Soil seed bank responses to edge effects in temperate European forests

  2022. Cristina Gasperini (et al.). Global Ecology and Biogeography 31 (9), 1877-1893

  Artikel

  Aim: The amount of forest edges is increasing globally due to forest fragmentation and land-use changes. However, edge effects on the soil seed bank of temperate forests are still poorly understood. Here, we assessed edge effects at contrasting spatial scales across Europe and quantified the extent to which edges can preserve the seeds of forest specialist plants.

  Location: Temperate European deciduous forests along a 2,300-km latitudinal gradient.

  Time period: 2018-2021.

  Major taxa studied: Vascular plants.

  Methods: Through a greenhouse germination experiment, we studied how edge effects alter the density, diversity, composition and functionality of forest soil seed banks in 90 plots along different latitudes, elevations and forest management types. We also assessed which environmental conditions drive the seed bank responses at the forest edge versus interior and looked at the relationship between the seed bank and the herb layer species richness.

  Results: Overall, 10,108 seedlings of 250 species emerged from the soil seed bank. Seed density and species richness of generalists (species not only associated with forests) were higher at edges compared to interiors, with a negative influence of C : N ratio and litter quality. Conversely, forest specialist species richness did not decline from the interior to the edge. Also, edges were compositionally, but not functionally, different from interiors. The correlation between the seed bank and the herb layer species richness was positive and affected by microclimate.

  Main conclusions: Our results underpin how edge effects shape species diversity and composition of soil seed banks in ancient forests, especially increasing the proportion of generalist species and thus potentially favouring a shift in community composition. However, the presence of many forest specialists suggests that soil seed banks still play a key role in understorey species persistence and could support the resilience of our fragmented forests.

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• A call for consistency with the terms ‘wetter’ and ‘drier’ in climate change studies

  2021. Nina Roth (et al.). Environmental Evidence 10

  Artikel

  Ongoing and future hydroclimatic changes have large environmental and societal impacts. In terrestrial ecosystems, these changes are usually described with the terms ‘wetter’ and ‘drier’, which refer to the change in the quantity and/or presence of water, either as water fluxes or stocks. We conducted a literature review of almost 500 recent climate change studies to quantitatively investigate the consistency of the use of these terms across disciplines, regarding the hydroclimatic variables they are related to. We found that although precipitation is prevalently used to describe ‘wetter’ and ‘drier’ conditions, many other variables are also used to refer to changes in water availability between research fields, pointing to a varied perspective on the use of these terms. Some studies do not define the terms at all. In order to facilitate meta-analyses across disciplines, we therefore highlight the need to explicitly state which hydroclimatic variables authors are referring to. In this way, we hope that the terms ‘wetter’ and ‘drier’ used in scientific studies are easier to relate to hydroclimatic processes, which should facilitate the application by authorities and policy makers.

  Läs mer om A call for consistency with the terms ‘wetter’ and ‘drier’ in climate change studies

• Dispersal limitation, eutrophication and propagule pressure constrain the conservation value of Grassland Green Infrastructure

  2021. Danny Hooftman (et al.). Biological Conservation 258

  Artikel

  Semi-natural grasslands harbour many of Europe's species of conservation interest. Although larger grasslands are the focus of most conservation activity, many grassland fragments are scattered across landscapes –in small patches or along linear elements– which can form Grassland Green Infrastructure (GGI). GGI has the potential to enhance landscape diversity by creating functioning metacommunities comprising of large semi-natural grasslands and these surrounding fragments. While often highlighted in conservation policy, little is known about the biodiversity supported by green infrastructure itself and thus its conservation potential.

  To address this issue, we contrasted plant communities in 36 ‘core’ grassland sites across three European countries with communities in the surrounding GGI. We related compositional differences to amount and type of GGI habitat (patches or linear), and the distances for seed dispersal by livestock from core sites. We found substantial differences between the GGI and the core sites, with a mean 54% species turn-over. These differences indicated filtering of stress tolerant species characteristic of low nutrient conditions, and semi-natural grassland specialists. Species with poorer dispersal abilities declined strongly with increasing distances from the core sites. The many additional species in the GGI, not found in the core sites, were predominantly those with a competitive strategy and high seed dispersal ability.

  We conclude that the biodiversity-supporting role of GGI across Europe is severely constrained by eutrophication, dispersal limitation and external propagule pressure. Actions to improve the quality of GGI might include enhancing dispersal by livestock combined with more type-diversification and less intensively used grassland habitats.

  Läs mer om Dispersal limitation, eutrophication and propagule pressure constrain the conservation value of Grassland Green Infrastructure

• Drivers of carbon stocks in forest edges across Europe

  2021. Camille Meeussen (et al.). Science of the Total Environment 759

  Artikel

  Forests play a key role in global carbon cycling and sequestration. However, the potential for carbon drawdown is affected by forest fragmentation and resulting changes in microclimate, nutrient inputs, disturbance and productivity near edges. Up to 20% of the global forested area lieswithin 100 m of an edge and, even in temperate forests, knowledge on howedge conditions affect carbon stocks and howfar this influence penetrates into forest interiors is scarce. Here we studied carbon stocks in the aboveground biomass, forest floor and the mineral topsoil in 225 plots in deciduous forest edges across Europe and tested the impact of macroclimate, nitrogen deposition and smaller-grained drivers (e.g. microclimate) on these stocks. Total carbon and carbon in the aboveground biomass stock were on average 39% and 95% higher at the forest edge than 100 m into the interior. The increase in the aboveground biomass stock close to the edgewas mainly related to enhanced nitrogen deposition. No edge influence was found for stocks in the mineral topsoil. Edge-to-interior gradients in forest floor carbon changed across latitude: carbon stocks in the forest floor were higher near the edge in southern Europe. Forest floor carbon decreased with increasing litter quality (i.e. high decomposition rate) and decreasing plant area index, whereas higher soil temperatures negatively affected the mineral top soil carbon. Based on high-resolution forest fragmentation maps, we estimate that the additional carbon stored in deciduous forest edges across Europe amounts to not less than 183 Tg carbon, which is equivalent to the storage capacity of 1 million ha of additional forest. This study underpins the importance of including edge influences when quantifying the carbon stocks in temperate forests and stresses the importance of preserving natural forest edges and small forest patches with a high edge-to-interior surface area.

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• How do African elephants utilize the landscape during wet season? A habitat connectivity analysis for Sioma Ngwezi landscape in Zambia

  2021. Doubt Chibeya (et al.). Ecology and Evolution 11 (21), 14916-14931

  Artikel

  1. The influence of environmental factors on the distribution and persistence of African elephants (Loxodonta africana) is pertinent to policy makers and managers to formulate balanced plans for different land-use types.
  2. The study focuses on movement of elephants and how they utilize foraging areas in Sioma Ngwezi landscape in Zambia by answering the following questions: (1) Which environmental variables and land-cover class predict the movement of elephants during the wet season in Sioma Ngwezi landscape? (2) What is the wet season suitable habitat for elephants in Sioma Ngwezi landscape? (3) What are the major wet season movement corridors for elephants in Sioma Ngwezi landscape?
  3. We used GPS telemetry data from the collared elephants to assess habitat connectivity. Maximum entropy (MaxEnt) and linkage mapper were the tools used to predict habitat suitability, movement corridors, and barriers in the landscape during the wet season.
  4. The study identified elevation, land cover, and NDVI as the most important environmental predictors that modify the dispersal of elephants in the landscape during the wet season. Additionally, a total of 36 potential wet season corridors were identified connecting 15 core areas mainly used for foraging and protection from poachers in the landscape. Of these, 24 corridors were highly utilized and are suggested as priority corridors for elephant movement in the landscape.
  5. The identified wet season habitats and functional corridors may help to combat elephant poaching by patrolling areas with high relative probability of elephant presence. The findings may also help abate human–elephant conflict such as crop-raiding by managing identified corridors that run into agriculture zones in the game management area.

  Läs mer om How do African elephants utilize the landscape during wet season? A habitat connectivity analysis for Sioma Ngwezi landscape in Zambia

• How does a wetland plant respond to increasing temperature along a latitudinal gradient?

  2021. Regina Lindborg (et al.). Ecology and Evolution 11 (22), 16228-16238

  Artikel

  Global warming affects plant fitness through changes in functional traits and thereby ecosystem function. Wetlands are declining worldwide, and hence, ecosystem functions linked to wetlands are threatened. We use Caltha palustris a common wetland plant to study whether warming affects growth and reproduction differently depending on origin of source population, potentially affecting phenotypic response to local climate. We conducted a 2-year in situ temperature manipulation experiment using clone pairs of C. palustris in four regions, along a 1300-km latitudinal gradient of Sweden. Open-top chambers were used to passively increase temperature, paired with controls. Growth and reproductive traits were measured from 320 plants (four regions x five sites x two treatments x eight plants) over two consecutive seasons to assess the effect of warming over time. We found that warming increased plant height, leaf area, number of leaves, and roots. High-latitude populations responded more strongly to warming than low-latitude populations, especially by increasing leaf area. Warming increased number of flowers in general, but only in the second year, while number of fruits increased in low-latitude populations the first year. Prolonged warming leads to an increase in both number of leaves and flowers over time. While reproduction shows varying and regional responses to warming, impacts on plant growth, especially in high-latitude populations, have more profound effects. Such effects could lead to changes in plant community composition with increased abundance of fast-growing plants with larger leaves and more clones, affecting plant competition and ecological functions such as decomposition and nutrient retention. Effects of warming were highly context dependent; thus, we encourage further use of warming experiments to predict changes in growth, reproduction, and community composition across wetland types and climate gradients targeting different plant forms.

  Läs mer om How does a wetland plant respond to increasing temperature along a latitudinal gradient?

• Immigration credit of temperate forest herbs in fragmented landscapes—Implications for restoration of habitat connectivity

  2021. Jörg Brunet (et al.). Journal of Applied Ecology 58 (10), 2195-2206

  Artikel

  1. In many agricultural landscapes, it is important to restore networks of forests to provide habitat and stepping stones for forest specialist taxa. More knowledge is, however, needed on how to facilitate the immigration of such taxa in restored forest patches. Here, we present the first chronosequence study to quantify the dynamics of immigration credits of forest specialist plants in post-arable forest patches.
  2. We studied the distribution of herbaceous forest specialist plant species in 54 post-arable broadleaved forest patches along gradients of age (20–140 years since forest establishment), distance from ancient forest (0–2,600 m) and patch area (0.5–9.6 ha). With linear mixed models, we estimated the effects of these factors on species richness, patch means of four dispersal-related plant traits and with generalized linear models on the occurrence of 20 individual species.
  3. Post-arable forest patch age and spatial isolation from ancient forest, but not patch size, were important predictors for species richness of forest specialists, suggesting that also small patches are valuable for habitat connectivity. Compared to species richness in ancient forest stands, the immigration credit was reduced by more than 90% after 80 years in post-arable forest patches contiguous to ancient forest compared to 40% after 80 years and 60% after 140 years in isolated patches (at least 100 m to next forest). Tall-growing species with adaptations to long-distance dispersal were faster colonizers, whereas species with heavy diaspores and clonal growth were slower to colonize.
  4. Synthesis and applications. We show that post-arable oak plantations have a high potential for restoration of forest herb vegetation. Dispersal-related plant traits play a key role in explaining interspecific differences among forest specialists. To facilitate forest herb immigration across all functional groups in agricultural landscapes, we suggest to create clusters of relatively small new forest patches nearby older forest with source populations.

  Läs mer om Immigration credit of temperate forest herbs in fragmented landscapes—Implications for restoration of habitat connectivity

• Microclimatic edge-to-interior gradients of European deciduous forests

  2021. Camille Meeussen (et al.). Agricultural and Forest Meteorology 311

  Artikel

  Global forest cover is heavily fragmented. Due to high edge-to-surface ratios in small forest patches, a large proportion of forests is affected by edge influences involving steep microclimatic gradients. Although forest edges are important ecotones and account for 20% of the global forested area, it remains unclear how biotic and abiotic drivers affect forest edge microclimates at the continental scale. Here we report soil and air temperatures measured in 225 deciduous forest plots across Europe for two years. Forest stands were situated along a latitudinal gradient and subject to a varying vegetation structure as quantified by terrestrial laser scanning. In summer, the average offset of air and soil temperatures in forest edges compared to temperatures outside the forest amounted to -2.8 degrees C and -2.3 degrees C, respectively. Edge-to-interior summer temperature gradients were affected by the macroclimate and edge structure. From the edge onwards, larger offsets were observed in dense forest edges and in warmer, southern regions. In open forests and northern Europe, altered microclimatic conditions extended deeper into the forest and gradients were steeper. Canopy closure and plant area index were important drivers of summer offsets in edges, whereas in winter also the forest-floor biomass played a key role. Using high-resolution maps, we estimated that approximately 10% of the European broadleaved forests would be affected by altered temperature regimes. Gradual transition zones between forest and adjacent lands are valuable habitat types for edge species. However, if cool and moist forest interiors are desired, then (i) dense and complex forest edges, (ii) an undisturbed forested buffer zone of at least 12.5 m deep and (iii) trees with a high shade casting ability could all contribute to an increased offset. These findings provide important guidelines to mitigate edge influences, to protect typical forest microclimates and to adapt forest management to climate change.

  Läs mer om Microclimatic edge-to-interior gradients of European deciduous forests

• Multiscale drivers of carabid beetle (Coleoptera : Carabidae) assemblages in small European woodlands

  2021. Ronan Marrec (et al.). Global Ecology and Biogeography 30 (1), 165-182

  Artikel

  Aim: The spatio-temporal connectivity of forest patches in lowland agricultural landscapes and their age matter to explain current biodiversity patterns across regional as well as biogeographical extents, to the point that their effect exceeds the one of macroclimate for plant diversity in the understorey of temperate forests. Whether this remains true for other taxonomic groups is still largely unknown. Yet, this relative influence has important consequences for ecosystem functioning and the delivery of ecosystem services. Focusing on carabid beetle assemblages, we assessed the relative importance of macroclimatic, landscape and patch attributes in driving local species richness (alpha-diversity) and species dissimilarity between patches (beta-diversity).

  Location: Deciduous forest patches in seven regions along a 2,100-km-long latitudinal gradient across the European temperate forest biome, from southern France to central Sweden.

  Methods: We sampled 221 forest patches in two 5-km x 5-km landscape windows with contrasting management intensities. Carabid beetles were classified into four habitat-preference guilds: forest-specialist, forest-generalist, eurytopic and open-habitat species. We quantified the multi-level environmental influence using mixed-effects models and variation partitioning analysis.

  Results: We found that both alpha- and beta-diversity were primarily determined by macroclimate, acting as a large-scale ecological filter on carabid assemblages among regions. Forest-patch conditions, including biotic and abiotic heterogeneity as well as patch age (but not patch size), increased alpha-diversity of forest species. Landscape management intensity weakly influenced alpha-diversity of forest species, but increased the number of non-forest species in forest patches. Beta diversity of non-forest species increased with patch heterogeneity and decreased with landscape management intensity.

  Main conclusions: Our results highlight the leading role of broad macroclimatic gradients over local and landscape factors in determining the composition of local carabid communities, thereby shedding light on macroecological patterns of arthropod assemblages. This study emphasizes the urgent need for preserving ancient forest patches embedded in agricultural landscapes, even the small and weakly connected ones.

  Läs mer om Multiscale drivers of carabid beetle (Coleoptera : Carabidae) assemblages in small European woodlands

• Semi-natural habitats in boreal Europe: a rise of a social-ecological research agenda

  2021. Irina Herzon (et al.). Ecology and Society 26 (2)

  Artikel

  The European continent contains substantial areas of semi-natural habitats, mostly grasslands, which are among the most endangered habitats in Europe. Their continued existence depends on some form of human activity, for either production or conservation purposes, or both. We examined the share of semi-natural grasslands within the general grassland areas in boreal Europe. We reviewed research literature across the region to compile evidence on semi-natural grasslands and other semi-natural habitats, such as wooded pastures, in respect to a range of topics such as ecology, land-use change, socioeconomics, and production. We also explored drivers of the research agenda and outlined future research needs. Challenges are faced when defining and quantifying semi-natural habitats even across a restricted region. Agricultural development and other policies clearly impact the research agenda in various countries. There are recent signs of a shift from classical ecological studies toward more multidisciplinary and integrated research. To sufficiently address the threats faced by semi-natural habitats, political and research frameworks in the European Union should pay more attention to the social-ecological complexity inherent in their management and should support the engagement of various actors into participatory governance processes. This is in line with a full-farm approach implicit in high nature value farming systems.

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• Sensitivity to habitat fragmentation across European landscapes in three temperate forest herbs

  2021. Tobias Naaf (et al.). Landscape Ecology 36 (10), 2831-2848

  Artikel

  Context Evidence for effects of habitat loss and fragmentation on the viability of temperate forest herb populations in agricultural landscapes is so far based on population genetic studies of single species in single landscapes. However, forest herbs differ in their life histories, and landscapes have different environments, structures and histories, making generalizations difficult.

  Objectives We compare the response of three slow-colonizing forest herbs to habitat loss and fragmentation and set this in relation to differences in life-history traits, in particular their mating system and associated pollinators.

  Methods We analysed the herbs' landscape-scale population genetic structure based on microsatellite markers from replicate forest fragments across seven European agricultural landscapes.

  Results All species responded to reductions in population size with a decrease in allelic richness and an increase in genetic differentiation among populations. Genetic differentiation also increased with enhanced spatial isolation. In addition, each species showed unique responses. Heterozygosity in the self-compatible Oxalis acetosella was reduced in smaller populations. The genetic diversity of Anemone nemorosa, whose main pollinators are less mobile, decreased with increasing spatial isolation, but not that of the bumblebee-pollinated Polygonatum multiflorum.

  Conclusions Our study indicates that habitat loss and fragmentation compromise the long-term viability of slow-colonizing forest herbs despite their ability to persist for many decades by clonal propagation. The distinct responses of the three species studied within the same landscapes confirm the need of multi-species approaches. The mobility of associated pollinators should be considered an important determinant of forest herbs' sensitivity to habitat loss and fragmentation.

  Läs mer om Sensitivity to habitat fragmentation across European landscapes in three temperate forest herbs

• Small scale environmental variation modulates plant defence syndromes of understorey plants in deciduous forests of Europe

  2021. Pieter Sanczuk (et al.). Global Ecology and Biogeography 30 (1), 205-219

  Artikel

  Aim: Variation in plant defence traits has been frequently assessed along large-scale macroclimatic clines. In contrast, local-scale changes in the environment have recently been proposed to also modulate plant defence traits. Yet, the relative importance of drivers at both scales has never been tested. We aimed to quantify the relative importance of environmental drivers inherent to large and small spatial scales on the physical and chemical defence and tolerance to herbivory in understorey plant species of deciduous forests of Europe.

  Location: Deciduous forests in Europe.

  Time period: Present.

  Major taxa studied: Forest understorey plants.

  Methods: We sampled four typical ancient forest herbs (Anemone nemorosa, Oxalis acetosella, Deschampsia cespitosa, Milium effusum) along small and large spatial scale gradients (those driven by latitude, elevation, forest management and distance to the forest edge), and analysed a suite of nine constitutively expressed traits associated with overall resistance to herbivory, and their multivariate response to environmental clines.

  Results: Although our study included a large gradient in macroclimate, we found variation in the local environment at small spatial scales (i.e. soil nutrient concentration and forest structural complexity) to be more important in predicting plant resistance to herbivory.

  Main conclusions: In addition to macroclimatic conditions, subtle differences in forest microclimate and soil characteristics also played a major role in modulating plant defence phenotypes. These findings highlight the importance of the local habitat structure and environmental conditions in modulating plant resistance to herbivory.

  Läs mer om Small scale environmental variation modulates plant defence syndromes of understorey plants in deciduous forests of Europe

• Taxonomic, phylogenetic and functional diversity of understorey plants respond differently to environmental conditions in European forest edges

  2021. Karen De Pauw (et al.). Journal of Ecology 109 (7), 2629-2648

  Artikel

  1. Forest biodiversity world-wide is affected by climate change, habitat loss and fragmentation, and today 20% of the forest area is located within 100 m of a forest edge. Still, forest edges harbour a substantial amount of terrestrial biodiversity, especially in the understorey. The functional and phylogenetic diversity of forest edges have never been studied simultaneously at a continental scale, in spite of their importance for the forests' functioning and for communities' resilience to future change.
  2. We assessed nine metrics of taxonomic, phylogenetic and functional diversity of understorey plant communities in 225 plots spread along edge-to-interior gradients in deciduous forests across Europe. We then derived the relative effects and importance of edaphic, stand and landscape conditions on the diversity metrics.
  3. Here, we show that taxonomic, phylogenetic and functional diversity metrics respond differently to environmental conditions. We report an increase in functional diversity in plots with stronger microclimatic buffering, in spite of their lower taxonomic species richness. Additionally, we found increased taxonomic species richness at the forest edge, but in forests with intermediate and high openness, these communities had decreased phylogenetic diversity.
  4. Functional and phylogenetic diversity revealed complementary and important insights in community assembly mechanisms. Several environmental filters were identified as potential drivers of the patterns, such as a colder macroclimate and less buffered microclimate for functional diversity. For phylogenetic diversity, edaphic conditions were more important. Interestingly, plots with lower soil pH had decreased taxonomic species richness, but led to increased phylogenetic diversity, challenging the phylogenetic niche conservatism concept.
  5. Synthesis. Taxonomic, phylogenetic and functional diversity of understorey communities in forest edges respond differently to environmental conditions, providing insight into different community assembly mechanisms and their interactions. Therefore, it is important to look beyond species richness with phylogenetic and functional diversity approaches when focusing on forest understorey biodiversity.

  Läs mer om Taxonomic, phylogenetic and functional diversity of understorey plants respond differently to environmental conditions in European forest edges

• Training future generations to deliver evidence-based conservation and ecosystem management

  2021. Harriet Downey (et al.). Ecological Solutions and Evidence 2 (1)

  Artikel

  1. To be effective, the next generation of conservation practitioners and managers need to be critical thinkers with a deep understanding of how to make evidence-based decisions and of the value of evidence synthesis.

  2. If, as educators, we do not make these priorities a core part of what we teach, we are failing to prepare our students to make an effective contribution to conservation practice.

  3. To help overcome this problem we have created open access online teaching materials in multiple languages that are stored in Applied Ecology Resources. So far, 117 educators from 23 countries have acknowledged the importance of this and are already teaching or about to teach skills in appraising or using evidence in conservation decision-making. This includes 145 undergraduate, postgraduate or professional development courses.

  4. We call for wider teaching of the tools and skills that facilitate evidence-based conservation and also suggest that providing online teaching materials in multiple languages could be beneficial for improving global understanding of other subject areas.

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• Contrasting altitudinal variation of alpine plant communities along the Swedish mountains

  2020. Johannes Måsviken, Fredrik Dalerum, Sara A. O. Cousins. Ecology and Evolution 10 (11), 4838-4853

  Artikel

  Changes in abiotic factors along altitudinal and latitudinal gradients cause powerful environmental gradients. The topography of alpine areas generates environmental gradients over short distances, and alpine areas are expected to experience greater temperature increase compared to the global average. In this study, we investigate alpha, beta, and gamma diversity, as well as community structure, of vascular plant communities along altitudinal gradients at three latitudes in the Swedish mountains. Species richness and evenness decreased with altitude, but the patterns within the altitudinal gradient varied between sites, including a sudden decrease at high altitude, a monotonic decrease, and a unimodal pattern. However, we did not observe a decline in beta diversity with altitude at all sites, and plant communities at all sites were spatially nested according to some other factors than altitude, such as the availability of water or microtopographic position. Moreover, the observed diversity patterns did not follow the latitudinal gradient. We observed a spatial modularity according to altitude, which was consistent across sites. Our results suggest strong influences of site-specific factors on plant community composition and that such factors partly may override effects from altitudinal and latitudinal environmental variation. Spatial variation of the observed vascular plant communities appears to have been caused by a combination of processes at multiple spatial scales.

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• Contrasting microclimates among hedgerows and woodlands across temperate Europe

  2020. Thomas Vanneste (et al.). Agricultural and Forest Meteorology 281

  Artikel

  Hedgerows have the potential to facilitate the persistence and migration of species across landscapes, mostly due to benign microclimatic conditions. This thermal buffering function may become even more important in the future for species migration under climate change. Unfortunately, there is a lack of empirical studies quantifying the microclimate of hedgerows, particularly at broad geographical scales. Here we monitored sub-canopy temperatures using 168 miniature temperature sensors distributed along woodland-hedgerow transects, and spanning a 1600-km macroclimatic gradient across Europe. First, we assessed the variation in the temperature offset (that is, the difference between sub-canopy and corresponding macroclimate temperatures) for minimum, mean and maximum temperatures along the woodland-hedgerow transects. Next, we linked the observed patterns to macroclimate temperatures as well as canopy structure, overstorey composition and hedgerow characteristics. The sub-canopy versus macroclimate temperature offset was on average 0.10 degrees C lower in hedgerows than in woodlands. Minimum winter temperatures were consistently lower by 0.10 degrees C in hedgerows than in woodlands, while maximum summer temperatures were 0.80 degrees C higher, albeit mainly around the woodland-hedgerow ecotone. The temperature offset was often negatively correlated with macroclimate temperatures. The slope of this relationship was lower for maximum temperatures in hedgerows than in woodlands. During summer, canopy cover, tree height and hedgerow width had strong cooling effects on maximum mid-day temperatures in hedgerows. The effects of shrub height, shrub cover and shade-casting ability, however, were not significant. To our knowledge, this is the first study to quantify hedgerow microclimates along a continental-scale environmental gradient. We show that hedgerows are less efficient thermal insulators than woodlands, especially at high ambient temperatures (e.g. on warm summer days). This knowledge will not only result in better predictions of species distribution across fragmented landscapes, but will also help to elaborate efficient strategies for biodiversity conservation and landscape planning.

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• Direct and indirect effects of island size and wave exposure on shoreline arthropod diversity

  2020. Alma Strandmark (et al.). Journal of Biogeography 47 (4), 968-977

  Artikel

  Aim Available theories suggest that the species number increases with island size, but the relationship between island size and species density, the number of species per unit area, is less understood. Moreover, mechanisms connecting island size and species density are not always evident because small and large islands differ in physical characteristics other than island size. The purpose here was to disentangle direct and indirect effects of island size and wave exposure on the species density of arthropods from herb-dominated shore habitats. Location Islands in the Stockholm Archipelago, Sweden. Taxon Spiders (Araneae) and beetles (Coleoptera). Methods We collected spiders and beetles on vegetated shores on islands of varying sizes, and used structural equation models to disentangle direct and indirect island size and wave exposure effects on species density. Results Island size affected diversity of web-building spiders, predatory beetles and other beetles (detritivores and omnivores), direct and indirectly. Indirect effects arose because large islands have more trees and steeper slopes than small islands, both of which affected species occurrence. Because height above the sea level reduces the effect of wave exposure, there were effects of these variables on the forest cover and on the diversity of web-building spiders. Finally, surrounding forest cover and diversity of flowering plants within sites increased diversity of herbivore beetles and cursorial spiders, likely because these sites provide more diverse resources. Main conclusions The result that predictors for species density vary between functional groups, with mechanisms that may or may not relate to island size, suggest potential developments in island biogeography theories. Future studies of island size effects should also attempt to quantify indirect effects, and not only total effects.

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• Earlier onset of flowering and increased reproductive allocation of an annual invasive plant in the north of its novel range

  2020. Kenny Helsen (et al.). Annals of Botany 126 (6), 1005-1016

  Artikel

  • Background and Aims It remains unclear whether invasive species can maintain both high biomass and reproductive output across their invaded range. Along latitudinal gradients, allocation theory predicts that faster flowering onset at high latitudes results in maturation at smaller size and thus reduced reproductive output. For annual invasive plants, more favourable environmental conditions at low latitudes probably result in stronger competition of co-occurring species, potentially driving selection for higher investment in vegetative biomass, while harsher climatic conditions and associated reproductive uncertainty at higher latitudes could reduce selection for vegetative biomass and increased selection for high reproductive investment (stress-gradient hypothesis). Combined, these drivers could result in increased or constant reproductive allocation with increasing latitude.
  • Methods We quantified life-history traits in the invasive annual plant Impatiens glandulifera along a latitudinal gradient in Europe. By growing two successive glasshouse generations, we assessed genetic differentiation in vegetative growth and reproductive output across six populations, and tested whether onset of flowering drives this divergence.
  • Key Results Trait variation was mainly caused by genetic differentiation. As expected, flowering onset was progressively earlier in populations from higher latitudes. Plant height and vegetative biomass also decreased in populations from higher latitudes, as predicted by allocation theory, but their variation was independent of the variation in flowering onset. Reproductive output remained constant across latitudes, resulting in increased reproductive allocation towards higher latitudes, supporting the stress-gradient hypothesis. We also observed trait genetic differentiation among populations that was independent of latitude.
  • Conclusions We show that an annual invasive plant evolved several life-history traits across its invaded range in ~150 years. The evolution of vegetative and reproductive traits seems unconstrained by evolution of flowering onset. This genetic decoupling between vegetative and reproductive traits possibly contributes to the invasion success of this species.

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• Edge influence on understorey plant communities depends on forest management

  2020. Sanne Govaert (et al.). Journal of Vegetation Science 31 (2), 281-292

  Artikel

  Questions: Does the influence of forest edges on plant species richness and composition depend on forest management? Do forest specialists and generalists show contrasting patterns?

  Location: Mesic, deciduous forests across Europe.

  Methods: Vegetation surveys were performed in forests with three management types (unthinned, thinned 5-10 years ago and recently thinned) along a macroclimatic gradient from Italy to Norway. In each of 45 forests, we established five vegetation plots along a south-facing edge-to-interior gradient (n = 225). Forest specialist, generalist and total species richness, as well as evenness and proportion of specialists, were tested as a function of the management type and distance to the edge while accounting for several environmental variables (e.g. landscape composition and soil characteristics). Magnitude and distance of edge influence were estimated for species richness per management type.

  Results: Greatest total species richness was found in thinned forests. Edge influence on generalist plant species richness was contingent on the management type, with the smallest decrease in species richness from the edge-to-interior in unthinned forests. In addition, generalist richness increased with the proportion of forests in the surrounding landscape and decreased in forests dominated by tree species that cast more shade. Forest specialist species richness, however, was not affected by management type or distance to the edge, and only increased with pH and increasing proportion of forests in the landscape.

  Conclusions: Forest thinning affects the plant community composition along edge-to-interior transects of European forests, with richness of forest specialists and generalists responding differently. Therefore, future studies should take the forest management into account when interpreting edge-to-interior because both modify the microclimate, soil processes and deposition of polluting aerosols. This interaction is key to predict the effects of global change on forest plants in landscapes characterized by the mosaic of forest patches and agricultural land that is typical for Europe.

  Läs mer om Edge influence on understorey plant communities depends on forest management

• Grazing livestock increases both vegetation and seed bank diversity in remnant and restored grasslands

  2020. Rozália E. Kapás (et al.). Journal of Vegetation Science 31 (6), 1053-1065

  Artikel

  Questions: Restoring grasslands is of great importance to biodiversity conservation to counteract widespread, ongoing losses of plant species diversity. Using source populations in remnant habitats and increasing functional connectivity mediated by grazing animals within and between habitats can benefit grassland restoration efforts. Here we investigate how grazing contributes to vegetation and seed bank diversity and composition in remnant and restored grassland communities in fragmented landscapes.

  Location: Stockholm archipelago, Sweden.

  Methods: We investigated the effects of the presence or absence of grazing animals as potential elements of functional connectivity on grassland species composition in both the vegetation layer and in the seed bank. Species inventory and seed bank sampling were carried out in 2 m × 2 m plots in remnant grassland habitats and adjacent restored grasslands on former arable fields.

  Results: Species composition varied between remnant and restored grasslands, with management-dependent species more common in remnant grasslands. Remnant habitats with active grazing management contained a higher number of species in both the vegetation and seed bank compared to restored grasslands, but grazing reduced dispersal limitation from higher distance to source populations for specialist species. Where grazing was absent fewer plant species occurred in both the vegetation and in the seed bank.

  Conclusion: Our results show that grazing livestock play a key role in facilitating both spatial and temporal dispersal in fragmented grasslands. This results in increased species diversity in the vegetation and the seed bank of grazed grasslands compared to those maintained by mowing only. Functional connectivity provided by grazing management increases the possibility for species establishment from both the below-ground seed bank and the surrounding landscape, thus increasing the resilience of plant communities against disturbances or climatic changes.

  Läs mer om Grazing livestock increases both vegetation and seed bank diversity in remnant and restored grasslands

• High ecosystem service delivery potential of small woodlands in agricultural landscapes

  2020. Alicia Valdés (et al.). Journal of Applied Ecology 57 (1), 4-16

  Artikel

  Global forest loss and fragmentation have strongly increased the frequency of forest patches smaller than a few hectares. Little is known about the biodiversity and ecosystem service supply potential of such small woodlands in comparison to larger forests. As it is widely recognized that high biodiversity levels increase ecosystem functionality and the delivery of multiple ecosystem services, small, isolated woodlands are expected to have a lower potential for ecosystem service delivery than large forests hosting more species. We collected data on the diversity of six taxonomic groups covering invertebrates, plants and fungi, and on the supply potential of five ecosystem services and one disservice within 224 woodlands distributed across temperate Europe. We related their ability to simultaneously provide multiple ecosystem services (multiservice delivery potential) at different performance levels to biodiversity of all studied taxonomic groups (multidiversity), forest patch size and age, as well as habitat availability and connectivity within the landscape, while accounting for macroclimate, soil properties and forest structure. Unexpectedly, despite their lower multidiversity, smaller woodlands had the potential to deliver multiple services at higher performance levels per area than larger woodlands of similar age, probably due to positive edge effects on the supply potential of several ecosystem services. Biodiversity only affected multiservice delivery potential at a low performance level as well as some individual ecosystem services. The importance of other drivers of ecosystem service supply potential by small woodlands in agricultural landscapes also depended on the level of performance and varied with the individual ecosystem service considered. Synthesis and applications. Large, ancient woodlands host high levels of biodiversity and can therefore deliver a number of ecosystem services. In contrast, smaller woodlands in agricultural landscapes, especially ancient woodlands, have a higher potential to deliver multiple ecosystem services on a per area basis. Despite their important contribution to agricultural landscape multifunctionality, small woodlands are not currently considered by public policies. There is thus an urgent need for targeted policy instruments to ensure their adequate management and future conservation in order to either achieve multiservice delivery at high levels or to maximize the delivery of specific ecosystem services.

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• Plant diversity in hedgerows and road verges across Europe

  2020. Thomas Vanneste (et al.). Journal of Applied Ecology 57 (7), 1244-1257

  Artikel

  Linear landscape elements such as hedgerows and road verges have the potential to mitigate the adverse effects of habitat fragmentation and climate change on species, for instance, by serving as a refuge habitat or by improving functional connectivity across the landscape. However, so far this hypothesis has not been evaluated at large spatial scales, preventing us from making generalized conclusions about their efficacy and implementation in conservation policies. Here, we assessed plant diversity patterns in 336 vegetation plots distributed along hedgerows and road verges, spanning a macro-environmental gradient across temperate Europe. We compared herb-layer species richness and composition in these linear elements with the respective seed-source (core) habitats, that is, semi-natural forests and grasslands. Next, we assessed how these differences related to several environmental drivers acting either locally, at the landscape level or along the studied macro-ecological gradient. Across all regions, about 55% of the plant species were shared between forests and hedgerows, and 52% between grasslands and road verges. Habitat-specialist richness was 11% lower in the linear habitats than in the core habitats, while generalist richness was 14% higher. The difference in floristic composition between both habitat types was mainly due to species turnover, and not nestedness. Most notably, forest-specialist richness in hedgerows responded positively to tree cover, tree height and the proportion of forests in the surrounding landscape, while generalist richness was negatively affected by tree height and buffering effect of trees on subcanopy temperatures. Grassland and road verge diversity was mainly influenced by soil properties, with positive effects of basic cation levels on the number of specialists and those of bioavailable soil phosphorus on generalist diversity. Synthesis and applications. We demonstrate that linear landscape elements provide a potential habitat for plant species across Europe, including slow-colonizing specialists. Additionally, our results stress the possibility for land managers to modify local habitat features (e.g. canopy structure, subcanopy microclimate, soil properties, mowing regime) through management practices to enhance the colonization success of specialists in these linear habitats. These findings underpin the management needed to better conserving the biodiversity of agricultural landscapes across broad geographical scales.

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• Structural variation of forest edges across Europe

  2020. Camille Meeussen (et al.). Forest Ecology and Management 462

  Artikel

  Forest edges are interfaces between forest interiors and adjacent land cover types. They are important elements in the landscape with almost 20% of the global forest area located within 100 m of the edge. Edges are structurally different from forest interiors, which results in unique edge influences on microclimate, functioning and biodiversity. These edge influences have been studied for multiple decades, yet there is only limited information available on how forest edge structure varies at the continental scale, and which factors drive this potential structural diversity. Here we quantified the structural variation along 45 edge-to-interior transects situated along latitudinal, elevational and management gradients across Europe. We combined state-of-the-art terrestrial laser scanning and conventional forest inventory techniques to investigate how the forest edge structure (e.g. plant area index, stem density, canopy height and foliage height diversity) varies and which factors affect this forest edge structural variability. Macroclimate, management, distance to the forest edge and tree community composition all influenced the forest edge structural variability and interestingly we detected interactive effects of our predictors as well. We found more abrupt edge-to-interior gradients (i.e. steeper slopes) in the plant area index in regularly thinned forests. In addition, latitude, mean annual temperature and humidity all affected edge-to-interior gradients in stem density. We also detected a simultaneous impact of both humidity and management, and humidity and distance to the forest edge, on the canopy height and foliage height diversity. These results contribute to our understanding of how environmental conditions and management shape the forest edge structure. Our findings stress the need for site-specific recommendations on forest edge management instead of generalized recommendations as the macroclimate substantially influences the forest edge structure. Only then, the forest edge microclimate, functioning and biodiversity can be conserved at a local scale.

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• Does historical land use affect the regional distribution of fleshy-fruited woody plants?

  2019. Matilda Arnell, Sara A. O. Cousins, Ove Eriksson. PLOS ONE 14 (12)

  Artikel

  Species richness and composition of current vegetation may reflect historical land use. We develop and examine the hypothesis that regional distribution and richness of fleshy-fruited woody plants, a group sharing life-form and dispersal system, reflect historical land use in open or semi-open habitats. Historical land use was based on maps from around the year 1900 for two regions in Sweden, and field data was gathered from surveys made in these regions. Species richness was positively related to historical land use indicated as open habitat in 1900. In one of the regions, five out of nine examined species were positively related to historical land use (with historical effect R-2 ranging between 0.03 and 0.22). In the other region, we found a weaker positive relationship with historical land use in two out of nine examined species (R-2 0.01 and 0.02). We conclude that current occurrence and richness of fleshy-fruited woody species is partly a legacy of historical land use, and that regions may vary in this respect. Based on a comparison between the two regions examined here, we discuss some potential causes behind this variation.

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• Exploring the effects of pasture trees on plant community patterns

  2019. Simon Jakobsson (et al.). Journal of Vegetation Science 30 (5), 809-820

  Artikel

  Questions

  We aim to answer three questions: (a) what are the effects of canopy shading of different tree species on seed germination of eight understorey grassland species? (b) how is plant species’ occurrence in understorey communities affected by differences in canopy cover and does that depend on tree species composition? and (c) are there mechanistic links between the effects of trees on species’ germination and their occurrence in the understorey plant community?

  Location

  Semi‐natural wooded pastures in the biosphere reserve Östra Vätterbranterna, southern Sweden.

  Methods

  In this study, we examined the germination of eight grassland plant species in a seed sowing experiment under natural conditions in the field. Seeds were sown beneath and outside the canopy of two tree species within 48 plots split up by four wooded pasture sites. We combined observed germination responses with a plant community survey to assess the effects of canopy cover in relation to tree species composition on plant community responses. We analysed these data in relation to species’ seed mass and vegetative shade tolerance.

  Results

  Shade‐tolerant species germinated better beneath compared to outside tree canopies, without any clear advantage of large‐seeded over small‐seeded species. As expected, species’ shade tolerance was also positively related to canopy cover within the understorey plant community. Importantly, we found strong tree species‐specific effects of canopy shading on the species’ germination response, but not on their presence within the plant community. However, optimal canopy cover conditions for germination and for the mature plants differed across grassland species and depended on tree species.

  Conclusions

  Our results show that different tree species play key ecosystem engineering roles in shaping wooded grassland plant community composition at the germination stage. Management practices favouring specific tree species may therefore be highly relevant for targeted biodiversity conservation of wooded semi‐natural grasslands.

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• Forest edges reduce slug (but not snail) activity-density across Western Europe

  2019. Pallieter De Smedt (et al.). Pedobiologia 75, 34-37

  Artikel

  Fragmentation strongly shapes the distribution of organisms within forest patches through contrasting environmental conditions between the edge and interior habitat. Edge-to-interior distribution patterns are, however, poorly studied for litter- and soil-dwelling fauna, such as terrestrial gastropods, despite their high densities and significant impact on ecosystem processes, as both herbivores and detritivores. Therefore, we investigated edge-to-interior abundance patterns of terrestrial gastropods in 224 fragmented forest patches across Western Europe. Catching over 15,000 gastropods, we found that slug abundance is reduced in forest edges, while snail abundance shows no response on the edge effect. We hypothesize that these patterns could be explained by higher drought tolerance of snails, since forest edges have reduced air and soil humidity and elevated temperatures compared to forest interiors. Reduced slug abundance in forest edges potentially has ecological consequences for herbivory in and outside forest patches and nutrient cycling.

  Läs mer om Forest edges reduce slug (but not snail) activity-density across Western Europe

• Functional trait variation of forest understorey plant communities across Europe

  2019. Thomas Vanneste (et al.). Basic and Applied Ecology 34, 1-14

  Artikel

  Global environmental changes are expected to alter the functional characteristics of understorey herb-layer communities, potentially affecting forest ecosystem functioning. However, little is known about what drives the variability of functional traits in forest understories. Here, we assessed the role of different environmental drivers in shaping the functional trait distribution of understorey herbs in fragmented forests across three spatial scales. We focused on 708 small, deciduous forest patches located in 16 agricultural landscape windows, spanning a 2500-km macroclimatic gradient across the temperate forest biome in Europe. We estimated the relative effect of patch-scale, landscape-scale and macroclimatic variables on the community mean and variation of plant height, specific leaf area and seed mass. Macroclimatic variables (monthly temperature and precipitation extremes) explained the largest proportion of variation in community trait means (on average 77% of the explained variation). In contrast, patch-scale factors dominated in explaining community trait variation (on average 68% of the explained variation). Notably, patch age, size and internal heterogeneity had a positive effect on the community-level variability. Landscape-scale variables explained only a minor part of the variation in both trait distribution properties. The variation explained by shared combinations of the variable groups was generally negligible. These findings highlight the importance of considering multiple spatial scales in predictions of environmental-change effects on the functionality of forest understories. We propose that forest management sustainability could benefit from conserving larger, historically continuous and internally heterogeneous forest patches to maximise ecosystem service diversity in rural landscapes.

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• Grazing networks promote plant functional connectivity among isolated grassland communities

  2019. Jan Plue, Tsipe Aavik, Sara A. O. Cousins. Diversity & distributions 25 (1), 102-115

  Artikel

  Aim Habitat loss threatens plant diversity globally. Lack of plant functional connectivity between isolated populations is often pinpointed as one of the major underlying mechanisms driving subsequent species extinctions. Therefore, landscape-scale conservation management promoting functional connectivity needs to be implemented urgently. Supporting the movement of seed dispersal vectors such as grazing animals may help safeguard local and regional plant diversity in fragmented landscapes. However, the efficacy of such management remains to be thoroughly assessed. Location Stockholm archipelago, Sweden. Methods We test how grazing animals may serve as mobile corridors within rotational grazing networks promoting plant functional connectivity via directed seed dispersal. Using landscape genetics, we compare isolated populations of the grassland perennial Campanula rotundifolia located in either active or abandoned grazing networks, to test if spatial patterns in their genetic diversity, differentiation and allele frequencies relate to the presence or absence of connectivity via rotational grazing management. Results Grazing networks imprinted strong landscape-scale spatial patterning in pairwise population genetic differentiation and within-population genetic diversity. Isolated C. rotundifolia populations functionally connected by grazing animals held higher genetic diversity compared to populations no longer connected by grazing livestock. Gene flow linked to the directed seed dispersal was higher between populations within grazing networks, confirmed by their increased allele richness. We found a predictable, nested loss of genetic diversity among C. rotundifolia populations in abandoned grazing networks. Main conclusions Grazing animals were important seed dispersal vectors, functionally connecting isolated grassland communities, so being vital to the successful long-term persistence and conservation of not only species but also genetic diversity. Crucially, the study underlines the possibilities of using domestic livestock as mobile corridors within rotational grazing networks as an effective tool to manage, conserve and restore both genetic and species diversity among isolated plant communities in fragmented landscapes.

  Läs mer om Grazing networks promote plant functional connectivity among isolated grassland communities

• Local soil characteristics determine the microbial communities under forest understorey plants along a latitudinal gradient

  2019. Shiyu Ma (et al.). Basic and Applied Ecology 36, 34-44

  Artikel

  The soil microbial community is essential for maintaining ecosystem functioning and is intimately linked with the plant community. Yet, little is known on how soil microbial communities in the root zone vary at continental scales within plant species. Here we assess the effects of soil chemistry, large-scale environmental conditions (i.e. temperature, precipitation and nitrogen deposition) and forest land-use history on the soil microbial communities (measured by phospholipid fatty acids) in the root zone of four plant species (Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica) in forests along a 1700 km latitudinal gradient in Europe. Soil microbial communities differed significantly among plant species, and soil chemistry was the main determinant of the microbial community composition within each plant species. Influential soil chemical variables for microbial communities were plant species-specific; soil acidity, however, was often an important factor. Large-scale environmental conditions, together with soil chemistry, only explained the microbial community composition in M. effusum and P. nemoralis. Forest land-use history did not affect the soil microbial community composition. Our results underpin the dominant role of soil chemistry in shaping microbial community composition variation within plant species at the continental scale, and provide insights into the composition and functionality of soil microbial communities in forest ecosystems.

  Läs mer om Local soil characteristics determine the microbial communities under forest understorey plants along a latitudinal gradient

• Mojito, Anyone? An Exploration of Low-Tech Plant Water Extraction Methods for Isotopic Analysis Using Locally-Sourced Materials

  2019. Benjamin M. C. Fischer (et al.). Frontiers in Earth Science 7

  Artikel

  The stable isotope composition of water (delta O-18 and delta H-2) is an increasingly utilized tool to distinguish between different pools of water along the soil-plant-atmosphere continuum (SPAC) and thus provides information on how plants use water. Clear bottlenecks for the ubiquitous application of isotopic analysis across the SPAC are the relatively high-energy and specialized materials required to extract water from plant materials. Could simple and cost-effective do-it-yourself MacGyver methods be sufficient for extracting plant water for isotopic analysis? This study develops a suite of novel techniques for plant water extraction and compares them to a standard research-grade water extraction method. Our results show that low-tech methods using locally-sourced materials can indeed extract plant water consistently and comparably to what is done with other state-of-the-art methods. Further, our findings show that other factors play a larger role than water extraction methods in achieving the desired accuracy and precision of stable isotope composition: (1) appropriate transport, (2) fast sample processing and (3) efficient workflows. These results are methodologically promising for the rapid expansion of isotopic investigations, especially for citizen science and/or school projects or in remote areas, where improved SPAC understanding could help manage water resources to fulfill agricultural and other competing water needs.

  Läs mer om Mojito, Anyone? An Exploration of Low-Tech Plant Water Extraction Methods for Isotopic Analysis Using Locally-Sourced Materials

• No genetic erosion after five generations for Impatiens glandulifera populations across the invaded range in Europe

  2019. Kenny Helsen (et al.). BMC Genetics 20

  Artikel

  Background

  The observation that many alien species become invasive despite low genetic diversity has long been considered the ‘genetic paradox’ in invasion biology. This paradox is often resolved through the temporal buildup genetic diversity through multiple introduction events. These temporal dynamics in genetic diversity are especially important for annual invasive plants that lack a persistent seed bank, for which population persistence is strongly dependent on consecutive seed ‘re-establishment’ in each growing season. Theory predicts that the number of seeds during re-establishment, and the levels of among-population gene flow can strongly affect recolonization dynamics, resulting in either an erosion or build-up of population genetic diversity through time. This study focuses on temporal changes in the population genetic structure of the annual invasive plant Impatiens glandulifera across Europe. We resampled 13 populations in 6 regions along a 1600 km long latitudinal gradient from northern France to central Norway after 5 years, and assessed population genetic diversity with 9 microsatellite markers.

  Results

  Our study suggests sufficiently high numbers of genetically diverse founders during population re-establishment, which prevent the erosion of local genetic diversity. We furthermore observe that I. glandulifera experiences significant among-population gene flow, gradually resulting in higher genetic diversity and lower overall genetic differentiation through time. Nonetheless, moderate founder effects concerning population genetic composition (allele frequencies) were evident, especially for smaller populations.

  Despite the initially low genetic diversity, this species seems to be successful at persisting across its invaded range, and will likely continue to build up higher genetic diversity at the local scale.

  Läs mer om No genetic erosion after five generations for Impatiens glandulifera populations across the invaded range in Europe

• Plant species identity and soil characteristics determine rhizosphere soil bacteria community composition in European temperate forests

  2019. Shiyu Ma (et al.). FEMS Microbiology Ecology 95 (6)

  Artikel

  Soil bacteria and understorey plants interact and drive forest ecosystem functioning. Yet, knowledge about biotic and abiotic factors that affect the composition of the bacterial community in the rhizosphere of understorey plants is largely lacking. Here, we assessed the effects of plant species identity (Milium effusum vs. Stachys sylvatica), rhizospheric soil characteristics, large-scale environmental conditions (temperature, precipitation and nitrogen (N) deposition), and land-use history (ancient vs. recent forests) on bacterial community composition in rhizosphere soil in temperate forests along a 1700 km latitudinal gradient in Europe. The dominant bacterial phyla in the rhizosphere soil of both plant species were Acidobacteria, Actinobacteria and Proteobacteria. Bacterial community composition differed significantly between the two plant species. Within plant species, soil chemistry was the most important factor determining soil bacterial community composition. More precisely, soil acidity correlated with the presence of multiple phyla, e.g. Acidobacteria (negatively), Chlamydiae (negatively) and Nitrospirae (positively), in both plant species. Large-scale environmental conditions were only important in S. sylvatica and land-use history was not important in either of the plant species. The observed role of understorey plant species identity and rhizosphere soil characteristics in determining soil bacterial community composition extends our understanding of plant-soil bacteria interactions in forest ecosystem functioning.

  Läs mer om Plant species identity and soil characteristics determine rhizosphere soil bacteria community composition in European temperate forests

• Plant-soil feedbacks of forest understorey plants transplanted in nonlocal soils along a latitudinal gradient

  2019. S. Ma (et al.). Plant Biology 21 (4), 677-687

  Artikel

  Climate change is driving movements of many plants beyond, as well as within, their current distributional ranges. Even migrant plants moving within their current range may experience different plant-soil feedbacks (PSF) because of divergent nonlocal biotic soil conditions. Yet, our understanding to what extent soil biotic conditions can affect the performance of within-range migrant plants is still very limited. We assessed the emergence and growth of migrant forest herbs (Milium effusum and Stachys sylvatica) using soils and seeds collected along a 1,700 km latitudinal gradient across Europe. Soil biota were manipulated through four soil treatments, i.e. unsterilized control soil (PSFUS), sterilized soil (PSFS), sterilized soil inoculated with unsterilized home soil (PSFS+HI) and sterilized soil inoculated with unsterilized foreign soil (PSFS+FI, expected to occur when both plants and soil biota track climate change). Compared to PSFS, PSFUS had negative effects on the growth but not emergence of both species, while PSFS+FI only affected S. sylvatica across all seed provenances. When considering seed origin, seedling emergence and growth responses to nonlocal soils depended on soil biotic conditions. Specifically, the home-away distance effect on seedling emergence differed between the four treatments, and significant responses to chemistry either disappeared (M. effusum) or changed (S. sylvatica) from PSFUS to PSFS. Soil biota emerge as an important driver of the estimated plant migration success. Our results of the effects of soil microorganisms on plant establishment provide relevant information for predictions of the distribution and dynamics of plant species in a changing climate.

  Läs mer om Plant-soil feedbacks of forest understorey plants transplanted in nonlocal soils along a latitudinal gradient

• Strength of forest edge effects on litter-dwelling macro-arthropods across Europe is influenced by forest age and edge properties

  2019. Pallieter De Smedt (et al.). Diversity & distributions 25 (6), 963-974

  Artikel

  Aim

  Forests are highly fragmented across Western Europe, making forest edges important features in many agricultural landscapes. Forest edges are subject to strong abiotic gradients altering the forest environment and resulting in strong biotic gradients. This has the potential to change the forest's capacity to provide multiple ecosystem services such as nutrient cycling, carbon sequestration and natural pest control. Soil organisms play a key role in this perspective; however, these taxa are rarely considered in forest edge research.

  Location

  A latitudinal gradient of 2,000 km across Western Europe.

  Methods

  We sampled six dominant taxa of litter-dwelling macro-arthropods (carabid beetles, spiders, harvestmen, centipedes, millipedes and woodlice) in forest edges and interiors of 192 forest fragments in 12 agricultural landscapes. We related their abundance and community composition to distance from the edge and the interaction with forest age, edge orientation and edge contrast (contrast between land use types at either side of the edge).

  Results

  Three out of six macro-arthropod taxa have higher activity-density in forest edges compared to forest interiors. The abundance patterns along forest edge-to-interior gradients interacted with forest age. Forest age and edge orientation also influenced within-fragment compositional variation along the forest edge-to-interior gradient. Edge contrast influenced abundance gradients of generalist predators. In general, older forest fragments, south-oriented edges and edges along structurally more continuous land use (lower contrast between forest and adjacent land use) resulted in stronger edge-to-interior gradients while recent forests, north-oriented edges and sharp land use edges induced similarity between forest edge and interior along the forest edge-to-interior gradients in terms of species activity-density and composition.

  Main conclusions

  Edge effects on litter-dwelling macro-arthropods are anticipated to feedback on important ecosystem services such as nutrient cycling, carbon sequestration and natural pest control from small forest fragments.

  Läs mer om Strength of forest edge effects on litter-dwelling macro-arthropods across Europe is influenced by forest age and edge properties

• Unbalanced species losses and gains lead to non-linear trajectories as grasslands become forests

  2019. Adam Kimberley, James M. Bullock, Sara A. O. Cousins. Journal of Vegetation Science 30 (6), 1089-1098

  Artikel

  Questions Rates of plant community shifts after environmental changes depend on how quickly affected species are gained and lost. Understanding how the balance between extinction and colonisation varies over time, and how it is influenced by local and landscape factors, is essential to understanding overall change trajectories. Investigating change requires data at several time steps over sufficient periods, and the paucity of such data represents an important knowledge gap. We ask: (a) how variation over time in the rates of species' extinction and species' colonization controls the trajectory of biodiversity change in abandoned semi-natural grasslands? and (b) can landscape composition and habitat history modify change trajectories by acting independently on groups within plant communities? Location Sweden, Stockholm Archipelago. Methods We use data on plant composition, management history and landscape context in former grasslands, abandoned at different points since 1901, in a space-for-time analysis, comparing rates of grassland species loss and forest species establishment and investigating resulting biodiversity trajectories. Results Grassland species declined steeply in recently abandoned habitats before levelling off, while the accumulation of forest species was linear, with no plateau reached even at the longest time since abandonment. Hence, we observed a trough in biodiversity, with an initial decline in overall species richness followed by a partial recovery. Only forest species gain was enhanced by nearby habitat availability. Conclusions Information on community compositional changes over short time periods may be misleading about the extent and even direction of ongoing biodiversity gains and losses. Moreover, the non-linear changes observed suggest thresholds in time, after which succession to the forest community accelerates and the ability to manage a return to the grassland community diminishes. Accounting for the combined influence of landscape composition and history is key to fully understanding community shifts over time.

  Läs mer om Unbalanced species losses and gains lead to non-linear trajectories as grasslands become forests

• Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa

  2018. P. De Frenne (et al.). Plant Biology 20 (3), 619-626

  Artikel

  Elevated atmospheric input of nitrogen (N) is currently affecting plant biodiversity and ecosystem functioning. The growth and survival of numerous plant species is known to respond strongly to N fertilisation. Yet, few studies have assessed the effects of N deposition on seed quality and reproductive performance, which is an important life-history stage of plants. Here we address this knowledge gap by assessing the effects of atmospheric N deposition on seed quality of the ancient forest herb Anemone nemorosa using two complementary approaches. By taking advantage of the wide spatiotemporal variation in N deposition rates in pan-European temperate and boreal forests over 2years, we detected positive effects of N deposition on the N concentration (percentage N per unit seed mass, increased from 2.8% to 4.1%) and N content (total N mass per seed more than doubled) of A.nemorosa seeds. In a complementary experiment, we applied ammonium nitrate to aboveground plant tissues and the soil surface to determine whether dissolved N sources in precipitation could be incorporated into seeds. Although the addition of N to leaves and the soil surface had no effect, a concentrated N solution applied to petals during anthesis resulted in increased seed mass, seed N concentration and N content. Our results demonstrate that N deposition on the petals enhances bioaccumulation of N in the seeds of A.nemorosa. Enhanced atmospheric inputs of N can thus not only affect growth and population dynamics via root or canopy uptake, but can also influence seed quality and reproduction via intake through the inflorescences.

  Läs mer om Atmospheric nitrogen deposition on petals enhances seed quality of the forest herb Anemone nemorosa

• Desiccation resistance determines distribution of woodlice along forest edge-to-interior gradients

  2018. Pallieter De Smedt (et al.). European journal of soil biology 85, 1-3

  Artikel

  Forest edges show strong abiotic and biotic gradients potentially altering community composition and ecosystem processes such as nutrient cycling. While abiotic gradients are well studied, short-scale biotic gradients, like detritivore species composition and their associated trait distribution remains a poorly explored research-field. We sampled woodlice in 160 forest patches across Europe at varying distances from the forest edge and discovered that species desiccation resistance determines distribution along forest edge-to-interior gradients. Forest edges are warmer and dryer compared to interiors and favour drought-tolerant species, while abundance and activity of drought-sensitive species is reduced at the edge. Key ecological factors for litter-dwelling detritivores (i.e. humidity) act as environmental filter, because of species-specific differences in desiccation resistance. Future research should focus on quantifying the consequences of a changing detritivore community and their associated functional traits for nutrient cycling.

  Läs mer om Desiccation resistance determines distribution of woodlice along forest edge-to-interior gradients

• Habitat properties are key drivers of Borrelia burgdorferi (s.l.) prevalence in Ixodes ricinus populations of deciduous forest fragments

  2018. Steffen Ehrmann (et al.). Parasites & Vectors 11

  Artikel

  Background

  The tick Ixodes ricinus has considerable impact on the health of humans and other terrestrial animals because it transmits several tick-borne pathogens (TBPs) such as B. burgdorferi (sensu lato), which causes Lyme borreliosis (LB). Small forest patches of agricultural landscapes provide many ecosystem services and also the disservice of LB risk. Biotic interactions and environmental filtering shape tick host communities distinctively between specific regions of Europe, which makes evaluating the dilution effect hypothesis and its influence across various scales challenging. Latitude, macroclimate, landscape and habitat properties drive both hosts and ticks and are comparable metrics across Europe. Therefore, we instead assess these environmental drivers as indicators and determine their respective roles for the prevalence of B. burgdorferi in I. ricinus.

  Methods

  We sampled I. ricinus and measured environmental properties of macroclimate, landscape and habitat quality of forest patches in agricultural landscapes along a European macroclimatic gradient. We used linear mixed models to determine significant drivers and their relative importance for nymphal and adult B. burgdorferi prevalence. We suggest a new prevalence index, which is pool-size independent.

  Results

  During summer months, our prevalence index varied between 0 and 0.4 per forest patch, indicating a low to moderate disservice. Habitat properties exerted a fourfold larger influence on B. burgdorferi prevalence than macroclimate and landscape properties combined. Increasingly available ecotone habitat of focal forest patches diluted and edge density at landscape scale amplified B. burgdorferi prevalence. Indicators of habitat attractiveness for tick hosts (food resources and shelter) were the most important predictors within habitat patches. More diverse and abundant macro and microhabitat had a diluting effect, as it presumably diversifies the niches for tick-hosts and decreases the probability of contact between ticks and their hosts and hence the transmission likelihood.

  Conclusions

  Diluting effects of more diverse habitat patches would pose another reason to maintain or restore high biodiversity in forest patches of rural landscapes. We suggest classifying habitat patches by their regulating services as dilution and amplification habitat, which predominantly either decrease or increase B. burgdorferi prevalence at local and landscape scale and hence LB risk. Particular emphasis on promoting LB-diluting properties should be put on the management of those habitats that are frequently used by humans. In the light of these findings, climate change may be of little concern for LB risk at local scales, but this should be evaluated further.

  Läs mer om Habitat properties are key drivers of Borrelia burgdorferi (s.l.) prevalence in Ixodes ricinus populations of deciduous forest fragments

• Impact of an invasive alien plant on litter decomposition along a latitudinal gradient

  2018. Kenny Helsen (et al.). Ecosphere 9 (1)

  Artikel

  Invasive alien plant effects on ecosystem functions are often difficult to predict across environmental gradients due to the context-dependent interactions between the invader and the recipient communities. Adopting a functional trait-based framework could provide more mechanistic predictions for invasive species' impacts. In this study, we contrast litter decomposition rates among communities with and without the invasive plant Impatiens glandulifera in five regions along a 1600 km long latitudinal gradient in Europe. Across this gradient, four functional traits, namely leaf dry matter content (LDMC), specific leaf area (SLA), stem-specific density (SSD), and plant height, are correlated to rates of litter decomposition of standardized rooibos (labile), green tea (recalcitrant), and I. glandulifera litter. Our results show that both invaded and non-invaded plant communities had a higher expression of acquisitive traits (low LDMC and SSD, high SLA) with increasing temperature along the latitudinal gradient, partly explaining the variation in decomposition rates along the gradient. At the same time, invasion shifted community trait composition toward more acquisitive traits across the latitudinal gradient. These trait changes partly explained the increased litter decomposition rates of the labile litter fraction of rooibos and I. glandulifera litter in invaded communities, a shift that was most evident in the warmer study regions. Plant available nitrogen was lower in invaded communities, likely due to high nutrient uptake by I. glandulifera. Meanwhile, the coldest study region was characterized by a reversed effect of invasion on decomposition rates. Here, community traits related to low litter quality and potential allelopathic effects of the invader resulted in reduced litter decomposition rates, suggesting a threshold temperature at which invader effects on litter decomposition turn positive. This study therefore illustrates how functional trait changes toward acquisitive traits can help explain invader-induced changes in ecosystem functions such as increased litter decomposition.

  Läs mer om Impact of an invasive alien plant on litter decomposition along a latitudinal gradient

• Land uplift creates important meadow habitat and a potential original niche for grassland species

  2018. Alistair G. Auffret, Sara A. O. Cousins. Proceedings of the Royal Society of London. Biological Sciences 285 (1876)

  Artikel

  Semi-natural grasslands have been severely affected by agricultural land-use change. However, the isostatic land adjustment following deglaciation in the Northern Hemisphere means that new land is continually being created in coastal areas. We modelled isostatic adjustment during the last 4000 years in a region of the Baltic coast to estimate the emergence of potential grassland habitat. We also compared the alpha and beta diversity of existing managed and abandoned coastal meadows, and assessed their contribution to biodiversity at landscape scales. We estimated that half the 7866 km(2) of emerging land had the potential to become coastal meadow habitat, which is an order of magnitude larger than the total area of all valuable semi-natural grassland in the study region today. The small area of managed coastal habitat remaining was found to have a disproportionate influence on the richness of threatened species at landscape scales, but our results also show that continued management is essential for the maintenance of grassland biodiversity. Our combination of approaches identifies uplifted coastal meadows as an additional original niche for grassland plant species, while highlighting that low-intensity disturbance through grassland management is essential for the maintenance of diversity at multiple scales.

  Läs mer om Land uplift creates important meadow habitat and a potential original niche for grassland species

• Linking macrodetritivore distribution to desiccation resistance in small forest fragments embedded in agricultural landscapes in Europe

  2018. Pallieter De Smedt (et al.). Landscape Ecology 33 (3), 407-421

  Artikel

  Most of the agricultural landscape in Europe, and elsewhere, consists of mosaics with scattered fragments of semi-natural habitat like small forest fragments. Mutual interactions between forest fragments and agricultural areas influence ecosystem processes such as nutrient cycling, a process strongly mediated by the macrodetritivore community, which is however, poorly studied. We investigated macrodetritivore distribution patterns at local and landscape-level and used a key functional trait (desiccation resistance) to gain mechanistic insights of the putative drivers.

  Läs mer om Linking macrodetritivore distribution to desiccation resistance in small forest fragments embedded in agricultural landscapes in Europe

• Local conditions in small habitats and surrounding landscape are important for pollination services, biological pest control and seed predation

  2018. Jessica Lindgren, Regina Lindborg, Sara A. O. Cousins. Agriculture, Ecosystems & Environment 251, 107-113

  Artikel

  Small semi-natural and natural habitats in agricultural landscapes are important for biodiversity. With modern and more intensive agricultural practices they have become smaller (less than 1600 m²) and more isolated study which also affects ecosystem functions. Most ecosystem function studies using field experiments focus on a single function. Here, we investigate three functions in the same landscape at the same time. We investigated how local (trees, shrubs and grass-cover in small remnant habitats) and landscape factors (amount of and distance from key habitats i.e. forest and semi-natural grasslands) affect pollination, biological pest control and seed predation. We applied a multifunctional approach using different organisms to analyze pollination success (Primula veris), predation on aphid pests (Rhopalosiphum padi) and seed predation (of Helianthus annuus). A set-up of 3 different experiments were placed in situ on 12 midfield islets. Pollination was more affected by local factors than landscape factors, although pollination success was improved by a smaller proportions of surrounding crop fields. Seed predation was higher on islets with more surrounding forest and also with more trees on the habitat, especially close to shrubs, compared to more open areas of habitat. Predation on aphids decreased on midfield islets with a larger amount of nearby forest but was positively affected by increasing local tree cover on the habitat.

  We show that managing semi-open habitats that are connected to other natural or semi-natural habitats can improve pollination success and biological pest and weed control, thus potentially increasing yield in surrounding crop fields.

  Läs mer om Local conditions in small habitats and surrounding landscape are important for pollination services, biological pest control and seed predation

• Seed dispersal in both space and time is necessary for plant diversity maintenance in fragmented landscapes

  2018. Jan Plue, Sara A. O. Cousins. Oikos 127 (6), 780-791

  Artikel

  Metacommunity theory emphasizes that seed dispersal not only limits but equally maintains plant diversity, though the latter receives little empirical attention. Discerning the temporal and spatial components of seed dispersal and understanding how their interaction shapes fragmented communities and maintains their diversity may be pivotal to further our ecological understanding of spatial and temporal seed dispersal and its implications for landscape-scale conservation management. To investigate the relative importance of spatial and temporal seed dispersal and their roles in maintaining plant diversity, the herb layer and seed bank of grassland communities were inventoried in 77 sites across abandoned and intact rotational grazing networks in a 100 km(2) fragmented grassland landscape in the Stockholm archipelago (Baltic Sea, Sweden). Besides analysing alpha- and beta-diversity patterns, nestedness analyses connect deterministic community changes and diversity losses with dispersal-related life-history traits and habitat specialization to identify the mechanism driving community changes and maintaining local diversity. The loss of rotational grazing networks caused community diversity declines via non-random extinctions of spatially and temporally poor dispersers, particularly among grassland specialists. Temporal seed dispersal halted further community disassembly, maintaining diversity in the abandoned grazing networks. Spatial dispersal within the intact grazing networks was found to be an overriding, homogenizing agent conserving diversity in both the herb layer and seed bank. This empirical evidence establishes how spatial and temporal seed dispersal interact to maintain diversity in fragmented landscapes. Poorly connected grasslands appear limited by spatial dispersal, yet are maintained by temporal seed dispersal. In fragmented landscapes where grazing networks are rarely present, temporal rather than spatial seed dispersal may be more important in maintaining species diversity, since effective spatial dispersal may be significantly diminished. The grazing network's efficacy at boosting spatial dispersal and upholding community diversity presents a powerful management tool to conserve local and regional species diversity.

  Läs mer om Seed dispersal in both space and time is necessary for plant diversity maintenance in fragmented landscapes

• Species richness and composition differ in response to landscape and biogeography

  2018. Elsa Aggemyr (et al.). Landscape Ecology 33 (12), 2273-2284

  Artikel

  Context Understanding how landscape patterns affect species diversity is of great importance in the fields of biogeography, landscape ecology and conservation planning, but despite the rapid advance in biodiversity analysis, investigations of spatial effects on biodiversity are still largely focused on species richness.

  Objectives We wanted to know if and how species richness and species composition are differentially driven by the spatial measures dominating studies in landscape ecology and biogeography. As both measures require the same limited presence/absence information, it is important to choose an appropriate diversity measure, as differing results could have important consequences for interpreting ecological processes.

  Methods We recorded plant occurrences on 112 islands in the Baltic archipelago. Species richness and composition were calculated for each island, and the explanatory power of island area and habitat heterogeneity, distance to mainland and structural connectivity at three different landscape sizes were examined.

  Results A total of 354 different plant species were recorded. The influence of landscape variables differed depending on which diversity measure was used. Island area and structural connectivity determined plant species richness, while species composition revealed a more complex pattern, being influenced by island area, habitat heterogeneity and structural connectivity.

  Conclusions Although both measures require the same basic input data, species composition can reveal more about the ecological processes affecting plant communities in fragmented landscapes than species richness alone. Therefore, we recommend that species community composition should be used as an additional standard measure of diversity for biogeography, landscape ecology and conservation planning.

  Läs mer om Species richness and composition differ in response to landscape and biogeography

• The Neolithic Plant Invasion Hypothesis: the role of preadaptation and disturbance in grassland invasion

  2018. Andrew S. MacDougall (et al.). New Phytologist 220 (1), 94-103

  Artikel

  A long-standing hypothesis is that many European plants invade temperate grasslands globally because they are introduced simultaneously with pastoralism and cultivation, to which they are 'preadapted' after millennia of exposure dating to the Neolithic era ('Neolithic Plant Invasion Hypothesis' (NPIH)). These 'preadaptations' are predicted to maximize their performance relative to native species lacking this adaptive history. Here, we discuss the explanatory relevance of the NPIH, clarifying the importance of evolutionary context vs other mechanisms driving invasion. The NPIH makes intuitive sense given established connections between invasion and agricultural-based perturbation. However, tests are often incomplete given the need for performance contrasts between home and away ranges, while controlling for other mechanisms. We emphasize six NPIH-based predictions, centring on trait similarity of invaders between home vs away populations, and differing perturbation responses by invading and native plants. Although no research has integrated all six predictions, we highlight studies suggesting preadaptation influences on invasion. Given that many European grasslands are creations of human activity from the past, current invasions by these flora may represent the continuation of processes dating to the Neolithic. Ironically, European Neolithic-derived grasslands are becoming rarer, reflecting changes in management and illustrating the importance of human influences on these species.

  Läs mer om The Neolithic Plant Invasion Hypothesis

• The complexity of forest borders determines the understory vegetation

  2018. Jessica Lindgren, Adam Kimberley, Sara A. O. Cousins. Applied Vegetation Science 21 (1), 85-93

  Artikel

  Questions: What are the most important drivers of plant species richness (γ-diversity) and species turnover (β-diversity) in the field layer of a forest edge? Does the tree and shrub species richness structure and complexity affect the richness of forest and grassland specialist species?

  Location: South-eastern Sweden.

  Methods: We sampled 50 forest edges with different levels of structural complexity in agricultural landscapes. In each border we recorded trees, shrubs and herb layer species in a 50 m transect parallel with the forest. We investigated species composition and species turnover in relationship to the proportions of gaps the border, the diversity of trees and shrubs and distance to semi-natural grasslands.

  Results: Total plant species richness in the field layer was mainly explained by the proportion of gaps to areas with full canopy cover, and tree diversity. Increasing number of gaps promoted higher diversity of grassland specialist species within the field layer, resulting in open forest borders with the highest overall species richness. Gaps did however have a negative impact on forest species richness. Conversely, increasing forest species richness was positively related to tree diversity but number of grassland specialist species was negatively affected by tree diversity.

  Conclusions: Managing forest borders, and therefore increasing the area of semi-open habitats in fragmented agricultural landscapes, gives future opportunities to create a network of suitable habitats for both grassland and deciduous forest specialist species. Such measures therefore have the potential to increase functional connectivity and support dispersal of species in homogeneous forest/agriculture landscapes.

  Läs mer om The complexity of forest borders determines the understory vegetation

• Biotic and abiotic drivers of intraspecific trait variation within plant populations of three herbaceous plant species along a latitudinal gradient

  2017. Kenny Helsen (et al.). BMC Ecology 17

  Artikel

  Background: The importance of intraspecific trait variation (ITV) is increasingly acknowledged among plant ecologists. However, our understanding of what drives ITV between individual plants (ITVBI) at the population level is still limited. Contrasting theoretical hypotheses state that ITVBI can be either suppressed (stress-reduced plasticity hypothesis) or enhanced (stress-induced variability hypothesis) under high abiotic stress. Similarly, other hypotheses predict either suppressed (niche packing hypothesis) or enhanced ITVBI (individual variation hypothesis) under high niche packing in species rich communities. In this study we assess the relative effects of both abiotic and biotic niche effects on ITVBI of four functional traits (leaf area, specific leaf area, plant height and seed mass), for three herbaceous plant species across a 2300 km long gradient in Europe. The study species were the slow colonizing Anemone nemorosa, a species with intermediate colonization rates, Milium effusum, and the fast colonizing, non-native Impatiens glandulifera.

  Results: Climatic stress consistently increased ITVBI across species and traits. Soil nutrient stress, on the other hand, reduced ITVBI for A. nemorosa and I. glandulifera, but had a reversed effect for M. effusum. We furthermore observed a reversed effect of high niche packing on ITVBI for the fast colonizing non-native I. glandulifera (increased ITVBI), as compared to the slow colonizing native A. nemorosa and M. effusum (reduced ITVBI). Additionally, ITVBI in the fast colonizing species tended to be highest for the vegetative traits plant height and leaf area, but lowest for the measured generative trait seed mass.

  Conclusions: This study shows that stress can both reduce and increase ITVBI, seemingly supporting both the stress-reduced plasticity and stress-induced variability hypotheses. Similarly, niche packing effects on ITVBI supported both the niche packing hypothesis and the individual variation hypothesis. These results clearly illustrates the importance of simultaneously evaluating both abiotic and biotic factors on ITVBI. This study adds to the growing realization that within-population trait variation should not be ignored and can provide valuable ecological insights.

  Läs mer om Biotic and abiotic drivers of intraspecific trait variation within plant populations of three herbaceous plant species along a latitudinal gradient

• Does the seed bank contribute to the build-up of a genetic extinction debt in the grassland perennial Campanula rotundifolia?

  2017. Jan Plue (et al.). Annals of Botany 120 (3), 373-385

  Artikel

  Background and Aims

  Habitat fragmentation threatens global biodiversity. Many plant species persist in habitat fragments via persistent life cycle stages such as seed banks, generating a species extinction debt. Here, seed banks are hypothesized to cause a temporal delay in the expected loss of genetic variation, which can be referred to as a genetic extinction debt, as a possible mechanism behind species extinction debts.

  Methods

  Fragmented grassland populations of Campanula rotundifolia were examined for evidence of a genetic extinction debt, investigating if the seed bank contributed to the extinction debt build-up. The genetic make-up of 15 above- and below-ground populations was analysed in relation to historical and current levels of habitat fragmentation, both separately and combined.

  Key Results

  Genetic diversity was highest in above-ground populations, though below-ground populations contained 8 % of unique alleles that were absent above-ground. Above-ground genetic diversity and composition were related to historical patch size and connectivity, but not current patch characteristics, suggesting the presence of a genetic extinction debt in the above-ground populations. No such relationships were found for the below-ground populations. Genetic diversity measures still showed a response to historical but not present landscape characteristics when combining genetic diversity of the above- and below-ground populations.

  Conclusions

  The fragmented C. rotundifolia populations exhibited a genetic extinction debt. However, the role of the seed banks in the build-up of this extinction debt is probably small, since the limited, unique genetic diversity of the seed bank alone seems unable to counter the detrimental effects of habitat fragmentation on the population genetic structure of C. rotundifolia.

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• Environmental drivers of Ixodes ricinus abundance in forest fragments of rural European landscapes

  2017. Steffen Ehrmann (et al.). BMC Ecology 17

  Artikel

  Background: The castor bean tick (Ixodes ricinus) transmits infectious diseases such as Lyme borreliosis, which constitutes an important ecosystem disservice. Despite many local studies, a comprehensive understanding of the key drivers of tick abundance at the continental scale is still lacking. We analyze a large set of environmental factors as potential drivers of I. ricinus abundance. Our multi-scale study was carried out in deciduous forest fragments dispersed within two contrasting rural landscapes of eight regions, along a macroclimatic gradient stretching from southern France to central Sweden and Estonia. We surveyed the abundance of I. ricinus, plant community composition, forest structure and soil properties and compiled data on landscape structure, macroclimate and habitat properties. We used linear mixed models to analyze patterns and derived the relative importance of the significant drivers. Results: Many drivers had, on their own, either a moderate or small explanatory value for the abundance of I. ricinus, but combined they explained a substantial part of variation. This emphasizes the complex ecology of I. ricinus and the relevance of environmental factors for tick abundance. Macroclimate only explained a small fraction of variation, while properties of macro- and microhabitat, which buffer macroclimate, had a considerable impact on tick abundance. The amount of forest and the composition of the surrounding rural landscape were additionally important drivers of tick abundance. Functional (dispersules) and structural (density of tree and shrub layers) properties of the habitat patch played an important role. Various diversity metrics had only a small relative importance. Ontogenetic tick stages showed pronounced differences in their response. The abundance of nymphs and adults is explained by the preceding stage with a positive relationship, indicating a cumulative effect of drivers. Conclusions: Our findings suggest that the ecosystem disservices of tick-borne diseases, via the abundance of ticks, strongly depends on habitat properties and thus on how humans manage ecosystems from the scale of the microhabitat to the landscape. This study stresses the need to further evaluate the interaction between climate change and ecosystem management on I. ricinus abundance.

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• Geophagic termite mounds as one of the resources for African elephants in Ugalla Game Reserve, Western Tanzania

  2017. Elikana Kalumanga, Donald G. Mpanduji, Sara A. O. Cousins. African Journal of Ecology 55 (1), 91-100

  Artikel

  Knowledge of the distribution and nutrient values of key resources supporting the survival of wildlife species is integral for an effective conservation planning and management of the species. In the Miombo ecosystem of the Ugalla Game Reserve, African elephants (Loxodonta africana Blumenbach 1797), eat soil, that is geophagy, from certain termite mounds. We mapped that all the geophagic termite mounds are exclusively situated in the flood plain. To understand why soils from some termite mounds are eaten, we collected and analysed soil samples from 10 geophagic termite mounds, seven nongeophagic termite mounds and 13 samples from the surrounding flood plain. Percentage of clay content did not differ significantly among the soil samples. Soils from geophagic termite mounds were richer in mineral elements compared with other soil samples. The results demonstrate that the driver for geophagic behaviour is related to rich mineral element contents found in geophagic termite mounds made of the mineral-enriching termites (Macrotermes). Thus, geophagic termite mounds play a role in elephant's dietary needs and possibly influence their movement patterns in Ugalla, as the elephants cannot obtain enough minerals from their feeds. Geophagic termite mounds should be protected from potential destructive land uses, such as airstrip construction.

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• HistMapR: Rapid digitization of historical land-use maps in R

  2017. Alistair G. Auffret (et al.). Methods in Ecology and Evolution 8 (11), 1453-1457

  Artikel

  Habitat destruction and degradation represent serious threats to biodiversity, and quantification of land-use change over time is important for understanding the consequences of these changes to organisms and ecosystem service provision. Comparing land use between maps from different time periods allows estimation of the magnitude of habitat change in an area. However, digitizing historical maps manually is time-consuming and analyses of change are usually carried out at small spatial extents or at low resolutions. HistMapR contains a number of functions that can be used to semi-automatically digitize historical land use according to a map's colours, as defined by the RGB bands of the raster image. We test the method on different historical land-use map series and compare results to manual digitizations. Digitization is fast, and agreement with manually digitized maps of around 80-90% meets common targets for image classification. We hope that the ability to quickly classify large areas of historical land use will promote the inclusion of land-use change into analyses of biodiversity, species distributions and ecosystem services.

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• Island biogeography theory outweighs habitat amount hypothesis in predicting plant species richness in small grassland remnants

  2017. Jessica P. Lindgren, Sara A. O. Cousins. Landscape Ecology 32 (9), 1895-1906

  Artikel

  Context

  The habitat amount hypothesis has rarely been tested on plant communities. It remains unclear how habitat amount affect species richness in habitat fragments compared to island effects such as isolation and patch size.

  Objectives

  How do patch size and spatial distribution compared to habitat amount predict plant species richness and grassland specialist plant species in small grassland remnants? How does sampling area affect the prediction of spatial variables on species richness?

  Methods

  We recorded plant species density and richness on 131 midfield islets (small remnants of semi-natural grassland) situated in 27 landscapes in Sweden. Further, we tested how habitat amount, compared to focal patch size and distance to nearest neighbor predicted species density and richness of plants and of grassland specialists.

  Results

  A total of 381 plant species were recorded (including 85 grassland specialist species). A combination of patch size and isolation was better in predicting both density and richness of species compared to habitat amount. Almost 45% of species richness and 23% of specialist species were explained by island biogeography parameters compared to 19 and 11% by the amount of habitat. A scaled sampling method increased the explanation level of island biogeography parameters and habitat amount.

  Conclusions

  Habitat amount as a concept is not as good as island biogeography to predict species richness in small habitats. Priority in landscape planning should be on larger patches rather than several small, even if they are close together. We recommend a sampling area scaled to patch size in small habitats.

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• Latitudinal variation of life-history traits of an exotic and a native impatiens species in Europe

  2017. Kamal Prasad Acharya (et al.). Acta Oecologica 81, 40-47

  Artikel

  Understanding the responses of invasive and native populations to environmental change is crucial for reliable predictions of invasions in the face of global change. While comparisons of responses across invasive species with different life histories have been performed before, comparing functional traits of congeneric native and invasive species may help to reveal driving factors associated with invasion. Here we compared morphological functional trait patterns of an invasive species (Impatiens parviflora) with its congeneric native species (I. noli-tangere) along an approximately 1600 km European latitudinal gradient from France (49 degrees 34'N) to Norway (63 degrees 40'N). Soil nitrogen was recorded during six weeks of the growing season, and light, soil moisture, and nutrient availability were estimated for each sampled population using community weighted means of indicator values for co-occurring species. Temperature data were gathered from nearby weather stations. Both the native and invasive species are taller at higher latitudes and this response is strongest in the invasive species. Seed mass and number of seeds per capsule increase in I. noli-tangere but decrease in I. parviflora towards higher latitudes. Surprisingly, plant height in the invasive I. parviflora decreases with increasing soil nitrogen availability. The latitudinal pattern in seed mass is positively related to temperature in I. noli-tangere and negatively in I. parviflora. Leaf area of both species decreases with increasing Ellenberg indicator values for nitrogen and light but increases with increasing soil moisture. Soil nitrogen concentrations and Ellenberg indicator values for nitrogen have significant positive (I. nolitangere) and negative (I. parviflora) effects on the number of seeds per capsule. Our results show that the native I. noli-tangere has efficient reproduction at its range edge while the invasive I. parviflora shows a marked decrease in seed size and seed number per capsule. These patterns are unrelated to the growth and obtained size of the plants: even low soil nitrogen availability in the north seemed not to limit plant growth and size. Our results suggest that the invasive I. parviflora tends to become more invasive at lower latitudes by producing heavier seeds and more seeds per capsule.

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• Methodological bias in the seed bank flora holds significant implications for understanding seed bank community functions

  2017. Jan Plue (et al.). Plant Biology 19 (2), 201-210

  Artikel

  Persistent seed banks are a key plant regeneration strategy, buffering environmental variation to allow population and species persistence. Understanding seed bank functioning within herb layer dynamics is therefore important. However, rather than assessing emergence from the seed bank in herb layer gaps, most studies evaluate the seed bank functioning via a greenhouse census. We hypothesise that greenhouse data may not reflect seed bank-driven emergence in disturbance gaps due to methodological differences. Failure in detecting (specialist) species may then introduce methodological bias into the ecological interpretation of seed bank functions using greenhouse data. The persistent seed bank was surveyed in 40 semi-natural grassland plots across a fragmented landscape, quantifying seedling emergence in both the greenhouse and in disturbance gaps. Given the suspected interpretational bias, we tested whether each census uncovers similar seed bank responses to fragmentation. Seed bank characteristics were similar between censuses. Census type affected seed bank composition, with >25% of species retrieved better by either census type, dependent on functional traits including seed longevity, production and size. Habitat specialists emerged more in disturbance gaps than in the greenhouse, while the opposite was true for ruderal species. Both censuses uncovered fragmentation-induced seed bank patterns. Low surface area sampling, larger depth of sampling and germination conditions cause underrepresentation of the habitat-specialised part of the persistent seed bank flora during greenhouse censuses. Methodological bias introduced in the recorded seed bank data may consequently have significant implications for the ecological interpretation of seed bank community functions based on greenhouse data.

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• Plant functional connectivity - integrating landscape structure and effective dispersal

  2017. Alistair G. Auffret (et al.). Journal of Ecology 105 (6), 1648-1656

  Artikel

  1. Dispersal is essential for species to survive the threats of habitat destruction and climate change. Combining descriptions of dispersal ability with those of landscape structure, the concept of functional connectivity has been popular for understanding and predicting species' spatial responses to environmental change. 2. Following recent advances, the functional connectivity concept is now able to move beyond landscape structure to consider more explicitly how other external factors such as climate and resources affect species movement. We argue that these factors, in addition to a consideration of the complete dispersal process, are critical for an accurate understanding of functional connectivity for plant species in response to environmental change. 3. We use recent advances in dispersal, landscape and molecular ecology to describe how a range of external factors can influence effective dispersal in plant species, and how the resulting functional connectivity can be assessed. 4. Synthesis. We define plant functional connectivity as the effective dispersal of propagules or pollen among habitat patches in a landscape. Plant functional connectivity is determined by a combination of landscape structure, interactions between plant, environment and dispersal vectors, and the successful establishment of individuals. We hope that this consolidation of recent research will help focus future connectivity research and conservation.

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• Spatial scale and specialization affect how biogeography and functional traits predict long-term patterns of community turnover

  2017. Alistair G. Auffret (et al.). Functional Ecology 31 (2), 436-443

  Artikel

  1. Immigration, extirpation and persistence of individual populations of species are key processes determining community responses to environmental change. However, they are difficult to study over long time periods without corresponding historical and modern-day species occurrences.

  2. We used historical and present-day plant species occurrence data from two different spatial scales (resolutions) to investigate the plant community turnover during the 20th century in a Baltic Sea archipelago. Patterns of turnover were analysed in relation to plant functional traits relating to dispersal and competition/persistence, as well as biogeographical variables.

  3. Turnover was largely driven by interactions between functional traits and measures of area, connectivity and distance to mainland. However, the combinations of traits and biogeographical variables that were most important for predicting immigration and extirpation differed between data sets, and between species associated with grassland management and the entire species pool.

  4. Taller plants were more likely to persist regardless of scale and biogeography, reflecting the grazing abandonment that occurred in the study area. Interactions between dispersal traits and biogeography were related to immigrations when the entire species pool was considered. However, increased dispersal potential, a smaller island size and increasing distance to mainland combined to promote extirpations in management-associated species. A perennial life span and seed banking contributed to species persistence. At the larger spatial scale, trait-driven turnover was not mediated by the biogeographical context.

  5. We showed that it is important to consider functional traits, biogeographical variables and their interactions when analysing community turnover over time. Furthermore, we found that the understanding of how combinations of traits and biogeography predict turnover depends on the source and spatial scale of the available data, and the species pool analysed.

  Läs mer om Spatial scale and specialization affect how biogeography and functional traits predict long-term patterns of community turnover

• The changing contribution of top-down and bottom-up limitation of mesopredators during 220 years of land use and climate change

  2017. Marianne Pasanen-Mortensen (et al.). Journal of Animal Ecology 86 (3), 566-576

  Artikel

  Apex predators may buffer bottom-up driven ecosystem change, as top-down suppression may dampen herbivore and mesopredator responses to increased resource availability. However, theory suggests that for this buffering capacity to be realized, the equilibrium abundance of apex predators must increase. This raises the question: will apex predators maintain herbivore/mesopredator limitation, if bottom-up change relaxes resource constraints? Here, we explore changes in mesopredator (red fox Vulpes vulpes) abundance over 220years in response to eradication and recovery of an apex predator (Eurasian lynx Lynx lynx), and changes in land use and climate which are linked to resource availability. A three-step approach was used. First, recent data from Finland and Sweden were modelled to estimate linear effects of lynx density, land use and winter temperature on fox density. Second, lynx density, land use and winter temperature was estimated in a 22650km(2) focal area in boreal and boreo-nemoral Sweden in the years 1830, 1920, 2010 and 2050. Third, the models and estimates were used to project historic and future fox densities in the focal area. Projected fox density was lowest in 1830 when lynx density was high, winters cold and the proportion of cropland low. Fox density peaked in 1920 due to lynx eradication, a mesopredator release boosted by favourable bottom-up changes - milder winters and cropland expansion. By 2010, lynx recolonization had reduced fox density, but it remained higher than in 1830, partly due to the bottom-up changes. Comparing 1830 to 2010, the contribution of top-down limitation decreased, while environment enrichment relaxed bottom-up limitation. Future scenarios indicated that by 2050, lynx density would have to increase by 79% to compensate for a projected climate-driven increase in fox density. We highlight that although top-down limitation in theory can buffer bottom-up change, this requires compensatory changes in apex predator abundance. Hence apex predator recolonization/recovery to historical levels would not be sufficient to compensate for widespread changes in climate and land use, which have relaxed the resource constraints for many herbivores and mesopredators. Variation in bottom-up conditions may also contribute to context dependence in apex predator effects.

  Läs mer om The changing contribution of top-down and bottom-up limitation of mesopredators during 220 years of land use and climate change

• Where does the community start, and where does it end? Including the seed bank to reassess forest herb layer responses to the environment

  2017. Jan Plue (et al.). Journal of Vegetation Science 28 (2), 424-435

  Artikel

  QuestionBelow-ground processes are key determinants of above-ground plant population and community dynamics. Still, our understanding of how environmental drivers shape plant communities is mostly based on above-ground diversity patterns, bypassing below-ground plant diversity stored in seed banks. As seed banks may shape above-ground plant communities, we question whether concurrently analysing the above- and below-ground species assemblages may potentially enhance our understanding of community responses to environmental variation. LocationTemperate deciduous forests along a 2000km latitudinal gradient in NW Europe. MethodsHerb layer, seed bank and local environmental data including soil pH, canopy cover, forest cover continuity and time since last canopy disturbance were collected in 129 temperate deciduous forest plots. We quantified herb layer and seed bank diversity per plot and evaluated how environmental variation structured community diversity in the herb layer, seed bank and the combined herb layer-seed bank community. ResultsSeed banks consistently held more plant species than the herb layer. How local plot diversity was partitioned across the herb layer and seed bank was mediated by environmental variation in drivers serving as proxies of light availability. The herb layer and seed bank contained an ever smaller and ever larger share of local diversity, respectively, as both canopy cover and time since last canopy disturbance decreased. Species richness and -diversity of the combined herb layer-seed bank community responded distinctly differently compared to the separate assemblages in response to environmental variation in, e.g. forest cover continuity and canopy cover. ConclusionsThe seed bank is a below-ground diversity reservoir of the herbaceous forest community, which interacts with the herb layer, although constrained by environmental variation in e.g. light availability. The herb layer and seed bank co-exist as a single community by means of the so-called storage effect, resulting in distinct responses to environmental variation not necessarily recorded in the individual herb layer or seed bank assemblages. Thus, concurrently analysing above- and below-ground diversity will improve our ecological understanding of how understorey plant communities respond to environmental variation.

  Läs mer om Where does the community start, and where does it end? Including the seed bank to reassess forest herb layer responses to the environment

• Connectivity and management enables fast recovery of plant diversity in new linear grassland elements

  2016. Simon Jakobsson, Katsue Fukamachi, Sara A. O. Cousins. Journal of Vegetation Science 27 (1), 19-28

  Artikel

  Questions: How does small linear grassland elements (paddy levees and road verges) contribute to plant diversity patterns in sites with modern or traditional management? Which factors determine small-scale plant species richness of small linear grassland elements in a Japanese agricultural landscape?

  Location: Shiga Prefecture, Japan.

  Methods: Aerial photos from 1963, 1985, 1995 and 2008 were used to investigate landscape changes and to measure landscape structures within a typical agricultural landscape (25km(2)). Plant diversity was investigated in ten paddy levees and ten road verges in each of four traditional (barely any land cover alterations after 1963) and five modern (almost completely changed after 1985) sites. -diversity (mean number of species per plot) and -diversity (total number of species) for all species, specialist and invasive species, respectively, were analysed in relation to site history types and landscape structures. Plot species richness was analysed in relation to site history type, patch age and width, proximity to forest and litter removal.

  Results: In total, 204 plant species were found, 55 species unique to traditional sites and 13 unique to modern sites. - and -diversity of paddy levees and road verges was significantly higher in traditional sites. Number of specialist species on paddy levees and number of invasive species in road verges was also higher in traditional sites. Age was the strongest predictor of plot species richness on levees; older levees supported higher species richness than younger ones. Litter removal was the strongest predictor (positive effect) of plot species richness in road verges.

  Conclusions: These results suggest that the colonization credit of new levees in modern sites is decreasing quite rapidly as species quickly establish, approaching almost the same richness values as in traditional sites. However, long continuity of traditional management is still one of the most important contributors to plant diversity and crucial for many species. But small grassland elements can still be of great significance for preserving and enhancing plant diversity in otherwise depleted landscapes, as long as they are managed and connected throughout the landscape.

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• Climate change effects on the Baltic Sea borderland between land and sea

  2015. Alma Strandmark (et al.). Ambio 44, s28-S38

  Artikel

  Coastal habitats are situated on the border between land and sea, and ecosystem structure and functioning is influenced by both marine and terrestrial processes. Despite this, most scientific studies and monitoring are conducted either with a terrestrial or an aquatic focus. To address issues concerning climate change impacts in coastal areas, a cross-ecosystem approach is necessary. Since habitats along the Baltic coastlines vary in hydrology, natural geography, and ecology, climate change projections for Baltic shore ecosystems are bound to be highly speculative. Societal responses to climate change in the Baltic coastal ecosystems should have an ecosystem approach and match the biophysical realities of the Baltic Sea area. Knowledge about ecosystem processes and their responses to a changing climate should be integrated within the decision process, both locally and nationally, in order to increase the awareness of, and to prepare for climate change impacts in coastal areas of the Baltic Sea.

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• Divergent regeneration responses of two closely related tree species to direct abiotic and indirect biotic effects of climate change

  2015. M. M. Caron (et al.). Forest Ecology and Management 342, 21-29

  Artikel

  Changing temperature and precipitation can strongly influence plant reproduction. However, also biotic interactions might indirectly affect the reproduction and recruitment success of plants in the context of climate change. Information about the interactive effects of changes in abiotic and biotic factors is essential, but still largely lacking, to better understand the potential effects of a changing climate on plant populations. Here we analyze the regeneration from seeds of Acer platanoides and Acer pseudoplatanus, two currently secondary forest tree species from seven regions along a 2200 km-wide latitudinal gradient in Europe. We assessed the germination, seedling survival and growth during two years in a common garden experiment where temperature, precipitation and competition with the understory vegetation were manipulated. A. platanoides was more sensitive to changes in biotic conditions while A. pseudoplatanus was affected by both abiotic and biotic changes. In general, competition reduced (in A. platanoides) and warming enhanced (in A. pseudoplatanus) germination and survival, respectively. Reduced competition strongly increased the growth of A. platanoides seedlings. Seedling responses were independent of the conditions experienced by the mother tree during seed production and maturation. Our results indicate that, due to the negative effects of competition on the regeneration of A. platanoides, it is likely that under stronger competition (projected under future climatic conditions) this species will be negatively affected in terms of germination, survival and seedling biomass. Climate-change experiments including both abiotic and biotic factors constitute a key step forward to better understand the response of tree species' regeneration to climate change.

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• Impacts of warming and changes in precipitation frequency on the regeneration of two Acer species

  2015. M. M. Caron (et al.). Flora 214, 24-33

  Artikel

  Climate projections indicate that temperatures will increase by up to 4.5 degrees C in Europe by the end of this century, and that more extreme rainfall events and longer intervening dry periods will take place. Climate change will likely affect all phases of the life cycle of plants, but plant reproduction has been suggested to be especially sensitive. Here, using a combination of approaches (soil heaters and different provenances along a latitudinal gradient), we analyzed the regeneration from seeds of Acer platanoides and A. pseudoplatanus, two tree species considered, from a management point of view, of secondary relevance. We studied germination, seedling survival and growth in a full-factorial experiment including warming and changes in watering frequency. Both species responded to warming, watering frequency and seed provenance, with stronger (negative) effects of warming and provenance than of watering frequency. In general, the central provenances performed better than the northernmost and southern-most provenances. We also detected interactive effects between warming, watering frequency and/or seed provenance. Based on these results, both species are expected to show dissimilar responses to the changes in the studied climatic factors, but also the impacts of climate change on the different phases of plant regeneration may differ in direction and magnitude. In general increases in the precipitation, frequency will stimulate germination while warming will reduce survival and growth. Moreover, the frequent divergent responses of seedlings along the latitudinal gradient suggest that climate change will likely have heterogeneous impacts across Europe, with stronger impacts in the northern and southern parts of the species' distribution ranges.

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• Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services

  2015. Bodil Elmhagen (et al.). Ecology and Society 20 (1)

  Artikel

  Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6 degrees C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.

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• Interacting effects of warming and drought on regeneration and early growth of Acer pseudoplatanus and A. platanoides

  2015. M. M. Caron (et al.). Plant Biology 17 (1), 52-62

  Artikel

  Climate change is acting on several aspects of plant life cycles, including the sexual reproductive stage, which is considered amongst the most sensitive life-cycle phases. In temperate forests, it is expected that climate change will lead to a compositional change in community structure due to changes in the dominance of currently more abundant forest tree species. Increasing our understanding of the effects of climate change on currently secondary tree species recruitment is therefore important to better understand and forecast population and community dynamics in forests. Here, we analyse the interactive effects of rising temperatures and soil moisture reduction on germination, seedling survival and early growth of two important secondary European tree species, Acer pseudoplatanus and A.platanoides. Additionally, we analyse the effect of the temperature experienced by the mother tree during seed production by collecting seeds of both species along a 2200-km long latitudinal gradient. For most of the responses, A.platanoides showed higher sensitivity to the treatments applied, and especially to its joint manipulation, which for some variables resulted in additive effects while for others only partial compensation. In both species, germination and survival decreased with rising temperatures and/or soil moisture reduction while early growth decreased with declining soil moisture content. We conclude that although A.platanoides germination and survival were more affected after the applied treatments, its initial higher germination and larger seedlings might allow this species to be relatively more successful than A.pseudoplatanus in the face of climate change.

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• Isolation by 454-sequencing and characterization of polymorphic microsatellite markers in the tetraploid perennial herb Campanula rotundifolia

  2015. Jan Plue (et al.). Conservation Genetics Resources 7 (3), 721-722

  Artikel

  Campanula rotundifolia is a perennial polyploid herb with a wide circumpolar distribution growing in a range of grassland, heathland and dune communities. The species is showing signs of strong decline in most parts of its range due to habitat degradation. Eight polymorphic microsatellites were developed using a 454-sequencing approach and subsequently characterized in 323 tetraploid individuals from 15 populations in a fragmented landscape in central Sweden. Between 7 and 26 alleles were observed per locus with observed and expected heterozygosity ranging between 0.71-0.98 and 0.71-0.93, respectively. C. rotundifolia may serve as a model species for studying the relative importance of life-history traits in genetic diversity responses to environmental changes.

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• Low genetic diversity despite multiple introductions of the invasive plant species Impatiens glandulifera in Europe

  2015. Jenny Hagenblad (et al.). BMC Genetics 16

  Artikel

  Background: Invasive species can be a major threat to native biodiversity and the number of invasive plant species is increasing across the globe. Population genetic studies of invasive species can provide key insights into their invasion history and ensuing evolution, but also for their control. Here we genetically characterise populations of Impatiens glandulifera, an invasive plant in Europe that can have a major impact on native plant communities. We compared populations from the species' native range in Kashmir, India, to those in its invaded range, along a latitudinal gradient in Europe. For comparison, the results from 39 other studies of genetic diversity in invasive species were collated. Results: Our results suggest that I. glandulifera was established in the wild in Europe at least twice, from an area outside of our Kashmir study area. Our results further revealed that the genetic diversity in invasive populations of I. glandulifera is unusually low compared to native populations, in particular when compared to other invasive species. Genetic drift rather than mutation seems to have played a role in differentiating populations in Europe. We find evidence of limitations to local gene flow after introduction to Europe, but somewhat less restrictions in the native range. I. glandulifera populations with significant inbreeding were only found in the species' native range and invasive species in general showed no increase in inbreeding upon leaving their native ranges. In Europe we detect cases of migration between distantly located populations. Human activities therefore seem to, at least partially, have facilitated not only introductions, but also further spread of I. glandulifera across Europe. Conclusions: Although multiple introductions will facilitate the retention of genetic diversity in invasive ranges, widespread invasive species can remain genetically relatively invariant also after multiple introductions. Phenotypic plasticity may therefore be an important component of the successful spread of Impatiens glandulifera across Europe.

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• Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient

  2015. Isgard H. Lemke (et al.). Plant Ecology 216 (11), 1523-1536

  Artikel

  Phenotypic trait variation plays a major role in the response of plants to global environmental change, particularly in species with low migration capabilities and recruitment success. However, little is known about the variation of functional traits within populations and about differences in this variation on larger spatial scales. In a first approach, we therefore related trait expression to climate and local environmental conditions, studying two temperate forest herbs, Milium effusum and Stachys sylvatica, along a similar to 1800-2500 km latitudinal gradient. Within each of 9-10 regions in six European countries, we collected data from six populations of each species and recorded several variables in each region (temperature, precipitation) and population (light availability, soil parameters). For each plant, we measured height, leaf area, specific leaf area, seed mass and the number of seeds and examined environmental effects on within-population trait variation as well as on trait means. Most importantly, trait variation differed both between and within populations. Species, however, differed in their response. Intrapopulation variation in Milium was consistently positively affected by higher mean temperatures and precipitation as well as by more fertile local soil conditions, suggesting that more productive conditions may select for larger phenotypic variation. In Stachys, particularly light availability positively influenced trait variation, whereas local soil conditions had no consistent effects. Generally, our study emphasises that intra-population variation may differ considerably across larger scales-due to phenotypic plasticity and/or underlying genetic diversity-possibly affecting species response to global environmental change.

  Läs mer om Patterns of phenotypic trait variation in two temperate forest herbs along a broad climatic gradient

• Population size and reproduction in the declining endangered forest plant Chimaphila umbellata in Sweden

  2015. Anna Lundell, Sara A. O. Cousins, Ove Eriksson. Folia Geobotanica 50 (1), 13-23

  Artikel

  The rare forest plant Chimaphila umbellata (Ericaceae) has decreased drastically during the last century, approximately by 80 % in some regions in Sweden. We examined associations between various biotic and abiotic conditions related to changes in forest management and nitrogen deposition, and C. umbellata population size, flowering frequency, fruit set and seed production. Environmental conditions at 38 C. umbellata sites in the provinces of Uppland and Sodermanland, Sweden, included light inflow, cover of competitive species, soil nitrogen, continuity of forest cover and soil texture. The results suggested that population size was negatively affected by cover of competitive species. Population size was not related to light availability although increased shading was associated with decreased flowering frequency. Fruit set was negatively affected by cover of competitive species, and seed production decreased with increasing soil nitrogen content. Fruit set and seed production increased with increasing population size. This study shows that denser forest stands and increased abundance of Vaccinium myrtillus and graminoid species may have strong negative effects on C. umbellata. This species' longevity and clonal propagation may buffer some negative impacts, which in turn might contribute to an extinction debt. To maintain viable populations of Chimaphila umbellata in Swedish forests, there is a need for targeted management in forest habitats, i.e. reintroducing moderate disturbance regimes to reduce competition and increase light inflow.

  Läs mer om Population size and reproduction in the declining endangered forest plant Chimaphila umbellata in Sweden

• Regional-scale land-cover change during the 20th century and its consequences for biodiversity

  2015. Sara A. O. Cousins (et al.). Ambio 44, S17-S27

  Artikel

  Extensive changes in land cover during the 20th century are known to have had detrimental effects on biodiversity in rural landscapes, but the magnitude of change and their ecological effects are not well known on regional scales. We digitized historical maps from the beginning of the 20th century over a 1652 km(2) study area in southeastern Sweden, comparing it to modern-day land cover with a focus on valuable habitat types. Semi-natural grassland cover decreased by over 96 % in the study area, being largely lost to afforestation and silviculture. Grasslands on finer soils were more likely to be converted into modern grassland or arable fields. However, in addition to remaining semi-natural grassland, today's valuable deciduous forest and wetland habitats were mostly grazed grassland in 1900. An analysis of the landscape-level biodiversity revealed that plant species richness was generally more related to the modern landscape, with grazing management being a positive influence on species richness.

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• Seed dispersal by ungulates as an ecological filter: a trait-based meta-analysis

  2015. Aurélie Albert (et al.). Oikos 124 (9), 1109-1120

  Artikel

  Plant communities are often dispersal-limited and zoochory can be an efficient mechanism for plants to colonize new patches of potentially suitable habitat. We predicted that seed dispersal by ungulates acts as an ecological filter - which differentially affects individuals according to their characteristics and shapes species assemblages - and that the filter varies according to the dispersal mechanism (endozoochory, fur-epizoochory and hoof-epizoochory). We conducted two-step individual participant data meta-analyses of 52 studies on plant dispersal by ungulates in fragmented landscapes, comparing eight plant traits and two habitat indicators between dispersed and non-dispersed plants. We found that ungulates dispersed at least 44% of the available plant species. Moreover, some plant traits and habitat indicators increased the likelihood for plant of being dispersed. Persistent or nitrophilous plant species from open habitats or bearing dry or elongated diaspores were more likely to be dispersed by ungulates, whatever the dispersal mechanism. In addition, endozoochory was more likely for diaspores bearing elongated appendages whereas epizoochory was more likely for diaspores released relatively high in vegetation. Hoof-epizoochory was more likely for light diaspores without hooked appendages. Fur-epizoochory was more likely for diaspores with appendages, particularly elongated or hooked ones. We thus observed a gradient of filtering effect among the three dispersal mechanisms. Endozoochory had an effect of rather weak intensity (impacting six plant characteristics with variations between ungulate-dispersed and non-dispersed plant species mostly below 25%), whereas hoof-epizoochory had a stronger effect (eight characteristics included five ones with above 75% variation), and fur-epizoochory an even stronger one (nine characteristics included six ones with above 75% variation). Our results demonstrate that seed dispersal by ungulates is an ecological filter whose intensity varies according to the dispersal mechanism considered. Ungulates can thus play a key role in plant community dynamics and have implications for plant spatial distribution patterns at multiple scales.

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• The contribution of patch-scale conditions is greater than that of macroclimate in explaining local plant diversity in fragmented forests across Europe

  2015. Alicia Valdés (et al.). Global Ecology and Biogeography 24 (9), 1094-1105

  Artikel

  AimMacroclimate is a major determinant of large-scale diversity patterns. However, the influence of smaller-scale factors on local diversity across large spatial extents is not well documented. Here, we quantify the relative importance of local (patch-scale), landscape-scale and macroclimatic drivers of herbaceous species diversity in small forest patches in agricultural landscapes across Europe. LocationDeciduous forest patches in eight regions along a macroclimatic gradient from southern France to central Sweden and Estonia. MethodsThe diversity of forest specialists and generalists at three levels (whole forest patch, sampling plots within patches and between scales) was related to patch-scale (forest area, age, abiotic and biotic heterogeneity), landscape-scale (amount of forest, grasslands and hedgerows around the patch, patch isolation) and macroclimatic variables (temperature and precipitation) using generalized linear mixed models and variation partitioning for each group of variables. ResultsThe total amount of explained variation in diversity ranged from 8% for plot-scale diversity of generalists to 54% for patch-scale diversity of forest specialists. Patch-scale variables always explained more than 60% of the explained variation in diversity, mainly due to the positive effect of within-patch heterogeneity on patch-scale and between-scale diversities and to the positive effect of patch age on plot-scale diversity of forest specialists. Landscape-scale variables mainly contributed to the amount of explained variation in plot-scale diversity, being more important for forest specialists (21%) than for generalists (18%). Macroclimatic variables contributed a maximum of 11% to the plot-scale diversity of generalists. Main conclusionsMacroclimate poorly predicts local diversity across Europe, and herbaceous diversity is mainly explained by habitat features, less so by landscape structure. We show the importance of conserving old forest patches as refugia for typical forest species, and of enhancing the landscape context around the patches by reducing the degree of disturbance caused by agriculture.

  Läs mer om The contribution of patch-scale conditions is greater than that of macroclimate in explaining local plant diversity in fragmented forests across Europe

• The spatial and temporal components of functional connectivity in fragmented landscapes

  2015. Alistair G. Auffret, Jan Plue, Sara A. O. Cousins. Ambio 44, s51-S59

  Artikel

  Connectivity is key for understanding how ecological systems respond to the challenges of land-use change and habitat fragmentation. Structural and functional connectivity are both established concepts in ecology, but the temporal component of connectivity deserves more attention. Whereas functional connectivity is often associated with spatial patterns (spatial functional connectivity), temporal functional connectivity relates to the persistence of organisms in time, in the same place. Both temporal and spatial processes determine biodiversity responses to changes in landscape structure, and it is therefore necessary that all aspects of connectivity are considered together. In this perspective, we use a case study to outline why we believe that both the spatial and temporal components of functional connectivity are important for understanding biodiversity patterns in the present-day landscape, and how they can also help us to make better-informed decisions about conserving and restoring landscapes and improving resilience to future change.

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• Effects of enhanced nitrogen inputs and climate warming on a forest understorey plant assessed by transplant experiments along a latitudinal gradient

  2014. Sybryn L. Maes (et al.). Plant Ecology 215 (8), 899-910

  Artikel

  Global warming and enhanced nitrogen (N) inputs are two key global-change drivers affecting temperate forest ecosystems simultaneously. Interactive effects of multiple drivers might cause species responses to differ from those in single-factor experiments; therefore, there is an urgent need for more multi-factor studies. Here, we assessed the growth and reproductive performance of multiple populations of a widespread grass of deciduous forests (Milium effusum) sampled along a latitudinal gradient and subjected to experimental manipulations of temperature and nitrogen availability. Common garden transplant experiments along the latitudinal gradient were used to manipulate temperatures and combined with experimental N addition to assess intraspecific responses of the study species to global-change drivers as well as to determine local adaptation. The total biomass, number of seeds and seedling emergence time of M. effusum increased when transplanted in the southern common garden. Apart from effects on the seed mass, the species did not respond to N addition alone. Yet, interactive effects between warming and N addition were found: N addition led to increased biomass growth but only in the northern common garden. Significant home-site advantages were apparent, most likely because of increased mycorrhizal colonization of roots of local transplants. We show that multiple global-change drivers may alter dynamics in understorey communities of temperate forests. Our study reinforces the need to increase our understanding of plant responses to future environmental changes by expanding the multi-factor research framework.

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• Function of small habitat elements for enhancing plant diversity in different agricultural landscapes

  2014. Regina Lindborg (et al.). Biological Conservation 169, 206-213

  Artikel

  The extensive transformation of agricultural landscapes worldwide has led to a decrease in grassland species related to traditional low-intensive farming. To properly manage and protect species, habitats and ecosystems in any of these landscapes requires a better understanding of direct and indirect effects of the processes driving biodiversity decline. In this study, we investigated how small habitat elements, represented by mid-field islets and road verges, in different types of agricultural landscapes can sustain a regional species pool for plant diversity otherwise associated to semi-natural grasslands. Although semi-natural grasslands had higher total and specialist richness, we found that small habitat elements harboured relatively high plant species richness, especially in a landscape with many semi-natural grasslands left. In the most intensively managed landscape, total richness declined as distance to the nearest semi-natural grassland increased. In contrast, beta-diversity was highest in these landscapes indicating that small habitats are also negatively affected by distance to grassland. We found that species trait composition varied depending on habitat and landscape. The results confirm that fragmentation shape trait composition within plant communities, e.g. plant size, clonality, longevity, and dispersal traits. We conclude that small habitat elements increase the total area available to grassland species present in the landscape, boosting the spatio-temporal dynamics of grassland communities. Small habitat elements may hence function as refugia or stepping stone habitats, especially in intensively utilized agricultural landscapes, and should be regarded as a functional part of a semi-natural grassland network, analogous to a meta-population.

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• Latitudinal variation in seeds characteristics of Acer platanoides and A. pseudoplatanus

  2014. M. M. Caron (et al.). Plant Ecology 215 (8), 911-925

  Artikel

  Climate change will likely affect population dynamics of numerous plant species by modifying several aspects of the life cycle. Because plant regeneration from seeds may be particularly vulnerable, here we assess the possible effects of climate change on seed characteristics and present an integrated analysis of seven seed traits (nutrient concentrations, samara mass, seed mass, wing length, seed viability, germination percentage, and seedling biomass) of Acer platanoides and A. pseudoplatanus seeds collected along a wide latitudinal gradient from Italy to Norway. Seed traits were analyzed in relation to the environmental conditions experienced by the mother trees along the latitudinal gradient. We found that seed traits of A. platanoides were more influenced by the climatic conditions than those of A. pseudoplatanus. Additionally, seed viability, germination percentage, and seedling biomass of A. platanoides were strongly related to the seed mass and nutrient concentration. While A. platanoides seeds were more influenced by the environmental conditions (generally negatively affected by rising temperatures), compared to A. pseudoplatanus, A. platanoides still showed higher germination percentage and seedling biomass than A. pseudoplatanus. Thus, further research on subsequent life-history stages of both species is needed. The variation in seed quality observed along the climatic gradient highlights the importance of studying the possible impact of climate change on seed production and species demography.

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• Open Access to Rural Landscapes!

  2014. Lowe Börjeson (et al.). Rural Landscapes 1 (1), 1-2

  Artikel

  The academic study of rural landscapes covers a broad range of academic disciplines and thematic, methodological and theoretical concerns and interests; including questions concerned with resource use (e.g. agriculture, forestry, water and mining), settlement, livelihoods, conflicts, conservation, culture and identity. This diversity is clearly a strength (the rich empirical and intellectual base), but also presents a challenge, as the dissemination of research findings is distributed through a plethora of publishing channels, which do not necessarily encourage exchange of results and ideas that are not already perceived as germane to already established academic networks.

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• Political Systems Affect Mobile and Sessile Species Diversity - A Legacy from the Post-WWII Period

  2014. Sara A. O. Cousins (et al.). PLOS ONE 9 (8), e103367

  Artikel

  Political ideologies, policies and economy affect land use which in turn may affect biodiversity patterns and future conservation targets. However, few studies have investigated biodiversity in landscapes with similar physical properties but governed by different political systems. Here we investigate land use and biodiversity patterns, and number and composition of birds and plants, in the borderland of Austria, Slovenia and Hungary. It is a physically uniform landscape but managed differently during the last 70 years as a consequence of the political map of Europe after World War I and II. We used a historical map from 1910 and satellite data to delineate land use within three 10-kilometre transects starting from the point where the three countries meet. There was a clear difference between countries detectable in current biodiversity patterns, which relates to land use history. Mobile species richness was associated with current land use whereas diversity of sessile species was more associated with past land use. Heterogeneous landscapes were positively and forest cover was negatively correlated to bird species richness. Our results provide insights into why landscape history is important to understand present and future biodiversity patterns, which is crucial for designing policies and conservation strategies across the world.

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• Climatic control of forest herb seed banks along a latitudinal gradient

  2013. Jan Plue (et al.). Global Ecology and Biogeography 22 (10), 1106-1117

  Artikel

  Aim Seed banks are central to the regeneration strategy of many plant species. Any factor altering seed bank density thus affects plant regeneration and population dynamics. Although seed banks are dynamic entities controlled by multiple environmental drivers, climatic factors are the most comprehensive, but still poorly understood. This study investigates how climatic variation structures seed production and resulting seed bank patterns. Location Temperate forests along a 1900km latitudinal gradient in north-western (NW) Europe. Methods Seed production and seed bank density were quantified in 153 plots along the gradient for four forest herbs with different seed longevity: Geum urbanum, Milium effusum, Poa nemoralis and Stachys sylvatica. We tested the importance of climatic and local environmental factors in shaping seed production and seed bank density. Results Seed production was determined by population size, and not by climatic factors. G.urbanum and M.effusum seed bank density declined with decreasing temperature (growing degree days) and/or increasing temperature range (maximum-minimum temperature). P.nemoralis and S.sylvatica seed bank density were limited by population size and not by climatic variables. Seed bank density was also influenced by other, local environmental factors such as soil pH or light availability. Different seed bank patterns emerged due to differential seed longevities. Species with long-lived seeds maintained constant seed bank densities by counteracting the reduced chance of regular years with high seed production at colder northern latitudes. Main conclusions Seed bank patterns show clear interspecific variation in response to climate across the distribution range. Not all seed banking species may be as well equipped to buffer climate change via their seed bank, notably in short-term persistent species. Since the buffering capacity of seed banks is key to species persistence, these results provide crucial information to advance climatic change predictions on range shifts, community and biodiversity responses.

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• Ecological niche shifts of understorey plants along a latitudinal gradient of temperate forests in north-western Europe

  2013. Safaa Wasof (et al.). Global Ecology and Biogeography 22 (10), 1130-1140

  Artikel

  Aim In response to environmental changes and to avoid extinction, species may either track suitable environmental conditions or adapt to the modified environment. However, whether and how species adapt to environmental changes remains unclear. By focusing on the realized niche (i.e. the actual space that a species inhabits and the resources it can access as a result of limiting biotic factors present in its habitat), we here examine shifts in the realized-niche width (i.e. ecological amplitude) and position (i.e. ecological optimum) of 26 common and widespread forest understorey plants across their distributional ranges. Location Temperate forests along a ca. 1800-km-long latitudinal gradient from northern France to central Sweden and Estonia. Methods We derived species' realized-niche width from a -diversity metric, which increases if the focal species co-occurs with more species. Based on the concept that species' scores in a detrended correspondence analysis (DCA) represent the locations of their realized-niche positions, we developed a novel approach to run species-specific DCAs allowing the focal species to shift its realized-niche position along the studied latitudinal gradient while the realized-niche positions of other species were held constant. Results None of the 26 species maintained both their realized-niche width and position along the latitudinal gradient. Few species (9 of 26: 35%) shifted their realized-niche width, but all shifted their realized-niche position. With increasing latitude, most species (22 of 26: 85%) shifted their realized-niche position for soil nutrients and pH towards nutrient-poorer and more acidic soils. Main conclusions Forest understorey plants shifted their realized niche along the latitudinal gradient, suggesting local adaptation and/or plasticity. This macroecological pattern casts doubt on the idea that the realized niche is stable in space and time, which is a key assumption of species distribution models used to predict the future of biodiversity, hence raising concern about predicted extinction rates.

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• Grassland connectivity by motor vehicles and grazing livestock

  2013. Alistair G. Auffret, Sara A.O. Cousins. Ecography 36 (10), 1150-1157

  Artikel

  In addition to habitat loss and fragmentation, agricultural change has led to a change in seed dispersal processes in therural landscape through a loss of structural and functional connectivity. Here, human-mediated dispersal vectors areprevalent, and we explored whether the loss of connectivity via free-ranging livestock could be mitigated by the increasein roads and motor vehicles. We found that structurally, 39% of all valuable semi-natural grassland habitats in southernSweden are adjacent to public road verges, which in the rural landscape are often considered to be suitable habitat forgrassland species. Additionally, by collecting mud attached to cars and farming machinery and manure from livestock(cattle, horse, sheep) grazing semi-natural grassland pasture, we found that motor vehicles are also capable seed dispers-ers. A similar number of species were dispersed by both vectors, although the composition of samples was quite different.Motor vehicles dispersed more grassland specialists than invasive species, although in much lower abundances than didgrazing livestock. Despite these differences, motor vehicles were found to be able to disperse species with the same kindsof dispersal traits as livestock. A high number of seeds, species and specialists in manure samples means that greater move-ment of livestock is desirable to increase functional grassland connectivity. However, effective management could improvethe suitability of roadsides as grassland corridors and increase the availability of seeds for long-distance human-mediateddispersal via cars and tractors. Our results suggest that in many rural landscapes, connectivity by road networks couldhelp mediate habitat loss and fragmentation of grasslands. However, such effects can be context dependent, and the con-nectivity provided by roads could have serious negative consequences in other regions.

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• Historical habitat connectivity affects current genetic structure in a grassland species

  2013. Z. Muenzbergova (et al.). Plant Biology 15 (1), 195-202

  Artikel

  Many recent studies have explored the effects of present and past landscape structure on species distribution and diversity. However, we know little about the effects of past landscape structure on distribution of genetic diversity within and between populations of a single species. Here we describe the relationship between present and past landscape structure (landscape connectivity and habitat size estimated from historical maps) and current genetic structure in a perennial herb, Succisa pratensis. We used allozymes as co-dominant markers to estimate genetic diversity and deviation from HardyWeinberg equilibrium in 31 populations distributed within a 5 km(2) agricultural landscape. The results showed that current genetic diversity of populations was related to habitat suitability, habitat age, habitat size and habitat connectivity in the past. The effects of habitat age and past connectivity on genetic diversity were in most cases also significant after taking the current landscape structure into account. Moreover, current genetic similarity between populations was affected by past connectivity after accounting for current landscape structure. In both cases, the oldest time layer (1850) was the most informative. Most populations showed heterozygote excess, indicating disequilibrium due to recent gene flow or selection against homozygotes. These results suggest that habitat age and past connectivity are important determinants of distribution of genetic diversity between populations at a scale of a few kilometres. Landscape history may significantly contribute to our understanding of distribution of current genetic structure within species and the genetic structure may be used to better understand landscape history, even at a small scale.

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• Humans as Long-Distance Dispersers of Rural Plant Communities

  2013. Alistair G. Auffret, Sara A. O. Cousins. PLOS ONE 8 (5)

  Artikel

  Humans are known for their capacity to disperse organisms long distances. Long-distance dispersal can be important for species threatened by habitat destruction, but research into human-mediated dispersal is often focused upon few and/or invasive species. Here we use citizen science to identify the capacity for humans to disperse seeds on their clothes and footwear from a known species pool in a valuable habitat, allowing for an assessment of the fraction and types of species dispersed by humans in an alternative context. We collected material from volunteers cutting 48 species-rich meadows throughout Sweden. We counted 24 354 seeds of 197 species, representing 34% of the available species pool, including several rare and protected species. However, 71 species (36%) are considered invasive elsewhere in the world. Trait analysis showed that seeds with hooks or other appendages were more likely to be dispersed by humans, as well as those with a persistent seed bank. More activity in a meadow resulted in more dispersal, both in terms of species and representation of the source communities. Average potential dispersal distances were measured at 13 km. We consider humans capable seed dispersers, transporting a significant proportion of the plant communities in which they are active, just like more traditional vectors such as livestock. When rural populations were larger, people might have been regular and effective seed dispersers, and the net rural-urban migration resulting in a reduction in humans in the landscape may have exacerbated the dispersal failure evident in declining plant populations today. With the fragmentation of habitat and changes in land use resulting from agricultural change, and the increased mobility of humans worldwide, the dispersal role of humans may have shifted from providers of regular local and landscape dispersal to providers of much rarer long-distance and regional dispersal, and international invasion.

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• Moving towards the edge: matrix matters!

  2013. Sara A. O. Cousins. Journal of Vegetation Science 24 (1), 7-8

  Artikel

  In this issue of the Journal of Vegetation Science, Chabrerie et al. use plant inventories and geographical data to investigate effects on species richness and turnover caused by management intensity in the surrounding matrix in new and old forest fragments. Although forest edge age was important, more intensive management of the matrix clearly sharpened the edgeinterior gradient.

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• Temporal dispersal in fragmented landscapes

  2013. Jan Plue, Sara A. O. Cousins. Biological Conservation 160, 250-262

  Artikel

  Despite a good understanding on how dispersal in space structures plant communities in fragmented landscapes, we know little about dispersal in time. Empirical evidence on temporal dispersal - the soil seed bank - is lacking, with only trait-based evidence on the seed banks' importance for species persistence in fragmented landscapes. Therefore, seed banks of remnant grassland fragments were analyzed in how they changed compared to semi-natural grasslands following fragmentation. We studied the historical trajectories in time since fragmentation, fragment size and habitat quality of 134 grassland plots, linking these to their seed bank and plant community to understand how seed banks temporally connect grassland fragments, potentially conserving the flora of historically large semi-natural grasslands. Seed-banking grassland species were present in similar proportions in all remnant grassland fragments. The seed bank composition changed with time since fragmentation started, triggered by the deterministic loss of grassland species, generating nested subsets of the seed banks of semi-natural grasslands. The spatial heterogeneity in seed bank composition among grassland fragments limited the loss of grassland species at the landscape scale. The seed bank became an increasingly important constituent of total plant diversity with time since fragmentation started, as grassland species stored an increasingly larger proportion of their local diversity in the seed bank. Temporal dispersal enables the prolonged presence and persistence of numerous typical grassland species in fragmented landscapes. The seed banks' storage effect of plant diversity is of considerable significance to efforts aimed at conserving and restoring plant diversity in fragmented landscapes.

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• COLONIZATION BY ROBINIA PSEUDOACACIA OF VARIOUS SOIL AND HABITAT TYPES OUTSIDE WOODLANDS IN A TRADITIONAL CENTRAL-EUROPEAN AGRICULTURAL LANDSCAPE

  2012. Danijel Ivajnsic, Sara A. O. Cousins, Mitja Kaligaric. Polish Journal of Ecology 60 (2), 301-309

  Artikel

  The invasiveness of Robinia pseudoacacia, one of the most invasive alien tree species in the agricultural landscapes of Central Europe, was studied in relation to its colonization of various soil and habitat types. The study area was a traditional agricultural landscape in Goricko Landscape Park (Slovenia), a hilly region, where half the territory is covered by forests and where R. pseudoacacia is also common. Habitat mapping in the field with a resolution of two meters was applied and further elaborated in GIS. It revealed 1307 patches colonized by R. pseudoacacia and belonging to 11 habitat types, covering 0.6% of the total study area. The most widespread were pure R. pseudoacacia stands, representing 69% of the total patch area. R. pseudoacacia is also abundantly present in small woodlots (19%) and in lowland and collinar riverine willow scrub (6%). The patches vary little in fractal dimension; the elongation index is highest in lowland and collinar riverine willow scrub, stream ash-alder woods and mixed stands. The most frequently invaded soil is pseudogley, with more than 38% of the total surface, followed by 21% for fluvisol and 17% for eutric cambisol. We confirmed that distance from nearest woodland is important, since almost 32% of the invaded patches are found at a distance of 1-100 meters from closed woodland.

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• Grazing networks provide useful functional connectivity for plants in fragmented systems

  2012. Alistair G. Auffret (et al.). Journal of Vegetation Science 23 (5), 970-977

  Artikel

  Question To what extent does the movement of animals between fragmented habitat patches provide functional connectivity via endozoochorous seed dispersal? Location The Stockholm archipelago, Sweden. Methods We followed all movements of livestock between islands during one grazing season. After each movement, manure was collected and its seed content assessed through seedling emergence. Seedling data were then compared to vegetation surveys from the grazed islands with regard to functional traits. Results Light- and nitrogen-demanding locally abundant species, and those with relatively small and persistent seeds were more likely to be moved between islands. For quantitative traits, only a subset of the available trait ranges were dispersed, with extreme values left behind. Species apparently specialized to other means of dispersal emerged from the manure samples. Neither dispersed traits nor seed density changed with timing of movement, but seed richness and diversity both increased throughout the season. The subsets of endozoochorously-dispersed species in the established vegetation were more similar than non-dispersed subsets between islands linked by livestock. Conclusions Grazing networks contribute to the connectivity of the core species in the system, and could provide useful tools for grassland management in fragmented landscapes.

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• Landscape context and management regime structure plant diversity in grassland communities

  2012. Reto Schmucki (et al.). Journal of Ecology 100 (5), 1164-1173

  Artikel

  1. Theoretical models show that environmental heterogeneity and dispersal are major determinants of species diversity at multiple scales, yet there are few studies from real landscapes that adequately integrate variation in the surrounding matrix. Understanding how landscape context and management influence species composition and diversity patterns across habitats and scales is an important goal in ecology with relevance for both management and conservation. 2. We used a system of 25 landscapes distributed across islands in the Baltic Sea to investigate the effect of current and historical landscape context and management on plant diversity and composition in grassland communities. Plant diversity was measured at three hierarchical scales (1 m2, habitat, landscape) in grazed fields and adjacent wood pastures to calculate a-, beta- and ?-diversity values across habitats and scales. 3. Structural equation modelling was used to model and quantify the effects of landscape context on species diversity and spatial turnover, and constraint analysis of principal coordinates to relate variation in species composition to landscape variables. 4. Proportion of open land, spacing and grazing intensity positively affected species diversity in both habitats, whereas the effect of historical landscape context was only significant in open fields. Plant diversity in field pastures was mainly determined by the number of species found at a small scale, while both local species density and spatial turnover were key determinants of diversity in wood pastures. 5. Habitat proximity influenced species composition as compositional similarity was higher between adjacent field and wood pastures compared to randomly paired habitats. Although increasing flow of propagules from adjacent patches can promote local coexistence, dispersal can result in spatial homogenization. 6. Synthesis. Plant diversity in grassland communities is substantially influenced by species occurring in adjacent habitats. While the effect of landscape context and management on small-scale diversity was consistent across habitats, the effect on spatial turnover was habitat specific. Our study shows that plant diversity is structured through the interplay between local and landscape processes and highlights that plant communities in specific habitat types cannot be considered in isolation from the surrounding landscape matrix.

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• Landscape structure and land use history influence changes in island plant composition after 100 years

  2012. Elsa Aggemyr, Sara A. O. Cousins. Journal of Biogeography 39 (9), 1645-1656

  Artikel

  Aim We investigated how current and historical land use and landscape structure affect species richness and the processes of extinction, immigration and species turnover. Location The northern part of the Stockholm archipelago, Baltic Sea, Sweden. We resurveyed 27 islands ranging from 0.3 to 33 ha in area. Methods We compared current plant survey data, cadastral maps and aerial photographs with records obtained from a survey in 1908, using databases and a digital elevation model to examine changes in plant community dynamics in space and time. We examined the effects of local and landscape structure and land use changes on plant species dynamics by using stepwise regression in relation to eight local and three landscape variables. The eight local variables were area, relative age, shape, soil heterogeneity, bedrock ratio, number of houses, forest cover change, and grazing 100 years ago. The three landscape variables were distance to mainland, distance to closest island with a farm 100 years ago, and structural connectivity. Hanskis connectivity measure was modified to incorporate both connectivity and fragmentation. Results The investigated islands have undergone drastic changes, with increasing forest cover, habitation, and abandonment of grassland management. Although the total species richness increased by 31% and mean island area by 23%, we found no significant increase in species richness per unit area. Local variables explain past species richness (100 years ago), whereas both local and landscape variables explain current species richness, extinctions, immigrations and species turnover. Grazing that occurred 100 years ago still influences species richness, even though grazing management was abandoned several decades ago. The evidence clearly shows an increase in nitrophilous plant species, particularly among immigrant species. Main conclusions This study highlights the importance of including land use history when interpreting current patterns of species richness. Furthermore, local environment and landscape patterns affect important ecological processes such as immigration, extinction and species turnover, and hence should be included when assessing the impact of habitat fragmentation and land use change. We suggest that our modified structural connectivity measure can be applied to other types of landscapes to investigate the effects of fragmentation and habitat loss.

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• Outside the boundary - land use changes in the surroundings of urban nature reserves

  2012. Sara Borgström, Sara Cousins, Regina Lindborg. Applied Geography 32 (2), 350-359

  Artikel

  The importance of the landscape surrounding a protected area for sustaining its values is frequently discussed in conservation literature. Studies on the interactions of urbanisation and nature conservation at the global scale suggest that protected nature attracts urbanisation, and that this in turn might negatively impact the area. However, studies specifically addressing such land use dynamics at city scale are largely missing. In this study we examine the change in proportion of built up area in two zones (500 m and 1000 m) surrounding 15 urban nature reserves in southern Sweden. By using comprehensive maps from the last 50 years, we compared the zones to the overall urbanisation in the cities to reveal discrepancies in land use surrounding the nature reserves. We found that the amount of built up area in the buffer zones surrounding nature reserves followed the same trend as the corresponding cities and this relation was stable over time, although the positive relationship was not significant. The establishment of nature reserves had no detectable effect on surrounding land use, however two distinguished groups of reserves were identified with either more or less built up area in buffers zones compared to cities. These differences were related to specific local drivers such as land ownership, land use history and nature reserve location. In contrast to earlier studies at global scale, our study did not show that nature reserves attract urbanisation. Instead, we stress that the great variety of contextual factors at the city scale makes quantitative analysis of this kind extremely difficult. However, a general neglect from planning and nature conservation agencies to recognise nature reserves’ dependence on the surrounding landscape configuration could be detrimental to sustain their values in the long-term. Hence we suggest that zones surrounding nature-protected areas should be planned and managed according to local land use history and current landscape conditions to enable and enhance necessary cross-boundary interactions.

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• The response of forest plant regeneration to temperature variation along a latitudinal gradient

  2012. Pieter De Frenne (et al.). Annals of Botany 109 (5), 1037-1046

  Artikel

  The response of forest herb regeneration from seed to temperature variations across latitudes was experimentally assessed in order to forecast the likely response of understorey community dynamics to climate warming. Seeds of two characteristic forest plants (Anemone nemorosa and Milium effusum) were collected in natural populations along a latitudinal gradient from northern France to northern Sweden and exposed to three temperature regimes in growth chambers (first experiment). To test the importance of local adaptation, reciprocal transplants were also made of adult individuals that originated from the same populations in three common gardens located in southern, central and northern sites along the same gradient, and the resulting seeds were germinated (second experiment). Seedling establishment was quantified by measuring the timing and percentage of seedling emergence, and seedling biomass in both experiments. Spring warming increased emergence rates and seedling growth in the early-flowering forb A. nemorosa. Seedlings of the summer-flowering grass M. effusum originating from northern populations responded more strongly in terms of biomass growth to temperature than southern populations. The above-ground biomass of the seedlings of both species decreased with increasing latitude of origin, irrespective of whether seeds were collected from natural populations or from the common gardens. The emergence percentage decreased with increasing home-away distance in seeds from the transplant experiment, suggesting that the maternal plants were locally adapted. Decreasing seedling emergence and growth were found from the centre to the northern edge of the distribution range for both species. Stronger responses to temperature variation in seedling growth of the grass M. effusum in the north may offer a way to cope with environmental change. The results further suggest that climate warming might differentially affect seedling establishment of understorey plants across their distribution range and thus alter future understorey plant dynamics.

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• A latitudinal gradient in seed nutrients of the forest herb Anemone nemorosa

  2011. P. De Frenne (et al.). Plant Biology 13 (3), 493-501

  Artikel

  The nutrient concentration in seeds determines many aspects of potential success of the sexual reproductive phase of plants, including the seed predation probability, efficiency of seed dispersal and seedling performance. Despite considerable research interest in latitudinal gradients of foliar nutrients, a similar gradient for seeds remains unexplored. We investigated a potential latitudinal gradient in seed nutrient concentrations within the widespread European understorey forest herb Anemone nemorosa L. We sampled seeds of A. nemorosa in 15 populations along a 1900-km long latitudinal gradient at three to seven seed collection dates post-anthesis and investigated the relative effects of growing degree-hours > 5 degrees C, soil characteristics and latitude on seed nutrient concentrations. Seed nitrogen, nitrogen:phosphorus ratio and calcium concentration decreased towards northern latitudes, while carbon:nitrogen ratios increased. When taking differences in growing degree-hours and measured soil characteristics into account and only considering the most mature seeds, the latitudinal decline remained particularly significant for seed nitrogen concentration. We argue that the decline in seed nitrogen concentration can be attributed to northward decreasing seed provisioning due to lower soil nitrogen availability or greater investment in clonal reproduction. This pattern may have large implications for the reproductive performance of this forest herb as the degree of seed provisioning ultimately co-determines seedling survival and reproductive success.

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• A trait-based analysis of the functional connectivity provided by mobile grazers in an island grazing system

  2011. Alistair Auffret (et al.). 8th IALE World Congress, Beijing 18-21 August 2011

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  The area of species-rich semi-natural grassland in Europe has declined dramatically duringthe past two centuries. The Stockholm archipelago was once a vibrant agricultural landscape,with the movement of livestock between islands forming an extensive grazing network. Likein much of Europe, agricultural industrialisation led to most grasslands either beingabandoned to become scrub or woodland, or converted to arable fields and subsequentlyreverted to relatively species-poor pasture. The restoration of these habitats to species-richgrassland communities has been a major goal, but restoration success has often been found tobe seed or dispersal limited. In island systems, the hostility of the matrix exacerbates thisproblem, but also provides an ideal study system for investigating the dispersal of plantspecies between fragmented habitats. One management strategy has been to restart smallgrazing networks to improve connectivity in the landscape, and in the summer of 2009, wecollected fresh manure samples from grazing cattle and sheep after movement by boatbetween islands. These were then grown in a greenhouse, and 5915 seedlings of 74 speciesemerged from the 18 samples, corresponding to 18 movements within the grazing network.Comparing the species dispersed with the vegetation communities in the donor and receiverislands, we assess the subset of species and species traits which were transported. We can thusexamine the extent of the functional connectivity provided by these mobile grazers, and theeffect that timing of movement has on the range of species and traits dispersed.

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• An intraspecific application of the leaf-height-seed ecology strategy scheme to forest herbs along a latitudinal gradient

  2011. Pieter De Frenne (et al.). Ecography 34 (1), 132-140

  Artikel

  We measured LHS traits in 41 Anemone nemorosa and 44 Milium effusum populations along a 1900-2300 km latitudinal gradient from N France to N Sweden. We then applied multilevel models to identify the effects of regional (temperature, latitude) and local (soil fertility and acidity, overstorey canopy cover) environmental factors on LHS traits. Both species displayed a significant 4% increase in plant height with every degree northward shift (almost a two-fold plant height difference between the southernmost and northernmost populations). Neither seed mass nor SLA showed a significant latitudinal cline. Temperature had a large effect on the three LHS traits of Anemone. Latitude, canopy cover and soil nutrients were related to the SLA and plant height of Milium. None of the investigated variables appeared to be related to the seed mass of Milium. The variation in LHS traits indicates that the ecological strategy determined by the position of each population in this three-factor triangle is not constant along the latitudinal gradient. The significant increase in plant height suggests greater competitive abilities for both species in the northernmost populations. We also found that the studied environmental factors affected the LHS traits of the two species on various scales: spring-flowering Anemone was affected more by temperature, whereas early-summer flowering Milium was affected more by local and other latitude-related factors. Finally, previously reported cross-species correlations between LHS traits and latitude were generally unsupported by our within-species approach.

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• Detection of extinction debt depends on scale and specialisation

  2011. Sara A. O. Cousins, Didrik Vanhoenacker. Biological Conservation 144 (2), 782-787

  Artikel

  Many plants can persist in landscapes for a long time after focal habitats have disappeared or become fragmented, which might contribute to an extinction debt. Delayed responses of plant occurrence have recently received great attention, particularly in conservation, although evidence for extinction debts is incongruent. Here we asked if we could detect an extinction debt for plant species after 100 years of fragmentation, depending on regional or local (gamma or alpha respectively) diversity measure used, and if all plant species or only habitat specialists were investigated. Historical and contemporary grassland patterns were analysed in 33 rural landscapes (each 1 km(2) in diameter) in south-eastern Sweden. Results show that managed semi-natural grassland had declined from 39% to 3% in 100 years. Diversity measured at regional scale was best explained by grassland extent 100 years ago, for both all species and grassland specialists. Present-day management, but neither present nor past grassland extent, was important for grassland specialists' occurrence at the local scale, although present-day grassland proportion had a positive influence on species richness at the local scale. We found evidence of an extinction debt at both local and regional scale when all species were included in the analysis, but not for grassland specialist species at the local scale. However, the extinction debt is still to be settled for grassland specialists at the regional scale, and therefore the estimation of extinction debts in fragmented habitats presents one of the greatest challenges for conservation today and in the future.

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• Interregional variation in the floristic recovery of post-agricultural forests

  2011. Pieter De Frenne (et al.). Journal of Ecology 99 (2), 600-609

  Artikel

  1. Worldwide, the floristic composition of temperate forests bears the imprint of past land use for decades to centuries as forests regrow on agricultural land. Many species, however, display significant interregional variation in their ability to (re)colonize post-agricultural forests. This variation in colonization across regions and the underlying factors remain largely unexplored. 2. We compiled data on 90 species and 812 species x study combinations from 18 studies across Europe that determined species' distribution patterns in ancient (i.e. continuously forested since the first available land use maps) and post-agricultural forests. The recovery rate (RR) of species in each landscape was quantified as the log-response ratio of the percentage occurrence in post-agricultural over ancient forest and related to the species-specific life-history traits and local (soil characteristics and light availability) and regional factors (landscape properties as habitat availability, time available for colonization, and climate). 3. For the herb species, we demonstrate a strong (interactive) effect of species' life-history traits and forest habitat availability on the RR of post-agricultural forest. In graminoids, however, none of the investigated variables were significantly related to the RR. 4. The better colonizing species that mainly belonged to the short-lived herbs group showed the largest interregional variability. Their recovery significantly increased with the amount of forest habitat within the landscape, whereas, surprisingly, the time available for colonization, climate, soil characteristics and light availability had no effect. 5. Synthesis. By analysing 18 independent studies across Europe, we clearly showed for the first time on a continental scale that the recovery of short-lived forest herbs increased with the forest habitat availability in the landscape. Small perennial forest herbs, however, were generally unsuccessful in colonizing post-agricultural forest even in relatively densely forested landscapes. Hence, our results stress the need to avoid ancient forest clearance to preserve the typical woodland flora.

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• Past and present management influences the seed bank and seed rain in a rural landscape mosaic

  2011. Alistair G. Auffret, Sara A. O. Cousins. Journal of Applied Ecology 48 (5), 1278-1285

  Artikel

  1. Seed bank and seed rain represent dispersal in time and space. They can be important sources of diversity in the rural landscape, where fragmented habitats are linked by their histories. 2. Seed bank, seed rain and above-ground vegetation were sampled in four habitat types (abandoned semi-natural grassland (ABA), grazed former arable field (FAF), mid-field islet (MFI) and grazed semi-natural grassland (SNG)) in a rural landscape in southern Sweden, to examine whether community patterns can be distinguished at large spatial scales and whether seed bank and seed rain are best explained by current, past or intended future vegetation communities. 3. We counted 54 357 seedlings of 188 species from 1190 seed bank and 797 seed rain samples. Seed bank, seed rain and above-ground vegetation communities differed according to habitat. Several species characteristic of managed grassland vegetation were present in the seed bank, seed rain and vegetation of the other habitats. 4. The seed banks of SNGs and the seed rain of the FAFs were generally better predicted by the surrounding above-ground vegetation than were the other habitat types. The seed rain of the grazed communities was most similar to the vegetation in the FAFs, while the seed banks of the abandoned grasslands most resembled the vegetation in SNGs. 5. Gap availability and seed input could be limiting the colonisation of target species in FAFs, while remnant populations in the seed bank and the presence of grassland specialists in the above-ground vegetation indicate that abandoned grasslands and mid-field islets could be valuable sources of future diversity in the landscape after restoration. 6. Synthesis and applications. SNG communities are able to form seed banks which survive land-use change, but their seed rain does not reflect their above-ground communities. It is important that grassland plants set seed. By connecting existing grasslands with restoration targets, increased disturbance in the target habitats would allow for colonisation via the seed bank or seed rain, while decreased grazing intensity would benefit seed production in the source grasslands. Otherwise, landscape-wide propagule availability might increase with a more varied timing and intensity of management.

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• Remnant Populations and Plant Functional Traits in Abandoned Semi-Natural Grasslands

  2011. Veronika A. Johansson, Sara A. O. Cousins, Ove Eriksson. Folia Geobotanica 46 (2-3), 165-179

  Artikel

  Although semi-natural grasslands in Europe are declining there is often a time delay in the local extinction of grassland species due to development of remnant populations, i.e., populations with an extended persistence despite a negative growth rate. The objectives of this study were to examine the occurrence of remnant populations after abandonment of semi-natural grasslands and to examine functional traits of plants associated with the development of remnant populations. We surveyed six managed semi-natural grasslands and 20 former semi-natural grasslands where management ceased 60-100 years ago, and assessed species response to abandonment, assuming a space-for-time substitution. The response of species was related to nine traits representing life cycle, clonality, leaf traits, seed dispersal and seed mass. Of the 67 species for which data allowed analysis, 44 species declined after grassland abandonment but still occurred at the sites, probably as remnant populations. Five traits were associated with the response to abandonment. The declining but still occurring species were characterized by high plant height, a perennial life form, possession of a perennial bud bank, high clonal ability, and lack of dispersal attributes promoting long-distance dispersal. Traits allowing plants to maintain populations by utilizing only a part of their life cycle, such as clonal propagation, are most important for the capacity to develop remnant populations and delay local extinction. A considerable fraction of the species inhabiting semi-natural grasslands maintain what is most likely remnant populations after more than 60 years of spontaneous succession from managed semi-natural grasslands to forest.

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• Temperature effects on forest herbs assessed by warming and transplant experiments along a latitudinal gradient

  2011. Pieter De Frenne (et al.). Global Change Biology 17 (10), 3240-3253

  Artikel

  Slow-colonizing forest understorey plants are probably not able to rapidly adjust their distribution range following large-scale climate change. Therefore, the acclimation potential to climate change within their actual occupied habitats will likely be key for their short-and long-term persistence. We combined transplant experiments along a latitudinal gradient with open-top chambers to assess the effects of temperature on phenology, growth and reproductive performance of multiple populations of slow-colonizing understorey plants, using the spring flowering geophytic forb Anemone nemorosa and the early summer flowering grass Milium effusum as study species. In both species, emergence time and start of flowering clearly advanced with increasing temperatures. Vegetative growth (plant height, aboveground biomass) and reproductive success (seed mass, seed germination and germinable seed output) of A. nemorosa benefited from higher temperatures. Climate warming may thus increase future competitive ability and colonization rates of this species. Apart from the effects on phenology, growth and reproductive performance of M. effusum generally decreased when transplanted southwards (e. g., plant size and number of individuals decreased towards the south) and was probably more limited by light availability in the south. Specific leaf area of both species increased when transplanted southwards, but decreased with open-top chamber installation in A. nemorosa. In general, individuals of both species transplanted at the home site performed best, suggesting local adaptation. We conclude that contrasting understorey plants may display divergent plasticity in response to changing temperatures which may alter future understorey community dynamics.

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• Land use change in Stockholm archipelago and the effect on grassland plant diversity and richness

  2010. Josefin Reimark, Sara A O Cousins.

  Konferens

  200 years of land use change and the relationship to present plant species richness was investigated on island in the Stockholm archipelago. The aim with the study is to explore how land use over time, especially grazing, affects richness today and in the future. The study area encompasses a rural landscape with long continuity of farming where on three of the larger islands four farmers are still active. It also includes the smaller so-called satellite islands belonging to the farms. Land cover and land use change was interpreted from maps and aerial photos creating four time-layers in a GIS (17-1800s, 1900s, 1950es and present-day). In 2009 plant species occurrence was measured on 36 islands with focus on grazed and non-grazed fields and surrounding forests. In each habitat plant occurrence was measured in 10 plots (1m2) as well as total species occurrence. The most substantial changes in land cover are a decline in semi-open forest, meadows and mid-field islets. Instead there is an increase in the number of houses and gardens and dense forest. 100 years ago there were 25 farms in the area. Grazed open habitat was most species rich with a mean of 15 species /m2. The results show that grazing is an essential part in maintaining species richness. However, by keeping areas open by clearing trees and shrubs can also slow down the extinction of grassland plant species.

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• Revisiting 27 islands in the Stockholm archipelago after a century – the effect of land use change on species composition

  2010. Elsa Aggemyr, Sara A. O. Cousins.

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  Läs mer om Revisiting 27 islands in the Stockholm archipelago after a century – the effect of land use change on species composition

• Significant effects of temperature on the reproductive output of the forest herb Anemone nemorosa L.

  2010. P De Frenne (et al.). Forest Ecology and Management 259 (4), 809-817

  Artikel

  Climate warming is already influencing plant migration in different parts of the world.Numerous modelshave been developed to forecast future plant distributions. Few studies, however, have investigated thepotential effect of warming on the reproductive output of plants. Understorey forest herbs in particular,have received little attention in the debate on climate change impacts.This study focuses on the effect of temperature on sexual reproductive output (number of seeds, seedmass, germination percentage and seedling mass) of Anemone nemorosa L., a model species for slowcolonizing herbaceous forest plants. We sampled seeds of A. nemorosa in populations along a 2400 kmlatitudinal gradient from northern France to northern Sweden during three growing seasons (2005, 2006and 2008). This study design allowed us to isolate the effects of accumulated temperature (GrowingDegree Hours; GDH) from latitude and the local abiotic and biotic environment. Germination and seedsowing trials were performed in incubators, a greenhouse and under field conditions in a forest. Finally,we disentangled correlations between the different reproductive traits of A. nemorosa along thelatitudinal gradient.We found a clear positive relationship between accumulated temperature and seed and seedlingtraits: reproductive output of A. nemorosa improved with increasing GDH along the latitudinal gradient.Seedmass and seedling mass, for instance, increased by 9.7% and 10.4%, respectively, for every 1000 8C hincrease in GDH.Wealso derived strong correlations between several seed and seedling traits both underfield conditions and in incubators. Our results indicate that seed mass, incubator-based germinationpercentage (Germ%Inc) and the output of germinable seeds (product of number of seeds and Germ%Incdivided by 100) from plants grown along a latitudinal gradient (i.e. at different temperature regimes)provide valuable proxies to parameterize key population processes in models.We conclude that (1) climate warming may have a pronounced positive impact on sexualreproduction of A. nemorosa and (2) climate models forecasting plant distributions would benefit fromincluding the temperature sensitivity of key seed traits and population processes.

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• Extinction debt in fragmented grasslands: paid or not?

  2009. Sara Cousins. Journal of Vegetation Science 20 (1), 3-7

  Artikel

  Fragmentation of grasslands and forests is considered amajor threat to biodiversity. In the case of plants, theeffect of fragmentation or landscape context is still unclearand published results are divergent. One explanation forthis divergence is the slow response of long-lived plants,creating an extinction debt. However, this has not beenempirically confirmed. In this study, data were compiledfrom broad-scale studies of grasslands from throughoutthe world that relate plant diversity to fragmentationeffects. Only seven studies from northern Europe, out ofa total 61, gave any information on actual habitat fragmentationin time and space. In landscapes with 410%grassland remaining, present-day species richness wasrelated to past landscape or habitat pattern. In landscapeswith o10% grassland remaining, in contrast, plant speciesrichness was more related to contemporary landscapeor habitat pattern. Studies from landscapes with 410%grassland remaining supported the concept of an extinctiondebt, while studies from more fragmented landscapesdid not provide any evidence of an extinction debt. Inorder to make generalisations about historical legacies onspecies diversity in grasslands it is important to consider arange of highly transformed landscapes, and not onlylandscapes with a high amount of grassland remaining.

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• After the hotspots are gone: land use history and grassland plant species diversity in a strongly transformed agricultural landscape

  2008. Sara A. O. Cousins, Ove Eriksson. Applied Vegetation Science 11 (3), 365-374

  Artikel

  Question: We asked how landscape configuration and present management influence plant species richness and abundance of habitat specialists in grasslands in a ‘modern’ (much exploited and transformed) agricultural Swedish landscape.

  Location: Selaön, south-eastern Sweden (59°24' N, 17°10' E).

  Methods: Present and past (150 and 50 years ago) landscape pattern was analysed in a 25 km² area. Species richness was investigated in 63 different grassland patches; grazed and abandoned semi-natural grasslands, and grazed ex-arable fields. Influence of landscape variables; area, past and present grassland connectivity, present management on total species richness, density and abundance of 25 grassland specialists was analysed.

  Results: Semi-natural grasslands (permanent unfertilised pastures or meadows formed by traditional agricultural methods) had declined from 60% 150 years ago to 5% today. There was a significant decline in species richness and density in abandoned semi-natural grasslands. Total species richness was influenced by present management, size and connectivity to present and past grassland pattern. Landscape variables did not influence species density in grazed semi-natural grassland suggesting that maintained grazing management makes grassland patches independent of landscape context. The abundance of 16 grassland specialists was mainly influenced by management and to some extent also by landscape variables.

  Conclusion: Although species richness pattern reflect management and to some extent landscape variables, the response of individual species may be idiosyncratic. The historical signal from past landscapes is weak on present-day species richness in highly transformed, agricultural landscapes. Generalizations of historical legacies on species diversity in grasslands should consider also highly transformed landscapes and not only landscapes with a high amount of diversity hotspots left.

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• Size and heterogeneity rather than landscape context determine plant species richness in semi-natural grasslands

  2007. Mathias Öster, Sara A. O. Cousins, Ove Eriksson. Journal of Vegetation Science 18 (6), 859-868

  Artikel

  Question: Is plant diversity in fragmented semi-natural grasslands related to present and historical landscape context?

  Location: Southern Sweden.

  Methods: Plant diversity was described at 30 semi-natural grassland sites in terms of total and specialist plant species richness at the site and species density at different scales (0.5–10 m²). These measures are commonly used to assess conservation value of semi-natural grasslands. Landscape context was measured as contemporary connectivity to other semi-natural grasslands, historical connectivity 50 years ago, amount of linear elements potentially suitable for dispersal (road verges, power line clearings), and amount of forest (inverse of the openness of the landscape).

  Results: The diversity measures were generally correlated with each other, implying that species richness in a subset of the grassland can predict the total richness. Plant species density at three scales (0.5 m², 10 m² and total) was related to the landscape context using an information theoretic approach. Results showed that total species richness increased with increased size of grasslands, contrary to earlier diversity studies in semi-natural grasslands. Larger grasslands were more heterogeneous than smaller grasslands, and this is a likely reason for the species-area relationship. Heterogeneity was also of high importance at the smaller scales (0.5 m², 10 m²). With increased amount of forest, total species richness increased but species density on 10 m² decreased. There was no influence of connectivity in either the contemporary or the historical landscape, contrary to previous studies.

  Conclusions: Grassland size and heterogeneity are of greater importance for plant diversity in semi-natural grassland, than grassland connectivity in the landscape.

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• The distribution of four grassland plant species in relation to landscape history of a Swedish rural area

  2007. Mikael Mildén, Sara Cousins, Ove Eriksson. Annales Botanici Fennici 44 (6), 416-426

  Artikel

  It is commonly agreed that landscape history is important for species distributions today. Here, we studied present-day regional population distribution and performance of four grassland species, the perennials Ranunculus bulbosus and Succisa pratensis, and the monocarpic "biennials" Carlina vulgaris and Tragopogon pratensis, in a Swedish rural landscape. We analysed the management history of their population patches, using vegetation maps from 1945 and 2001. Distributions of Succisa pratensis reflected the grassland occurrences in 1945 and Tragopogon pratensis was associated with the road network 60 years ago. Performance in different habitats also suggested an impact of land use on species distributions. For Ranunculus bulbosus and Carlina vulgaris the impact of landscape history was less obvious. Our results indicate that present-day distributions of some grassland species partly may be a legacy of previous semi-natural grassland patterns in rural Sweden, an insight that has valuable implications for assessments of long-term vulnerability of grassland species.

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• Longterm spatial dynamics of Succisa pratensis in a changing rural landscape: linking dynamical modelling with historical maps

  2006. T Herben (et al.). Journal of Ecology 94 (1), 131-143

  Artikel

  We attempt to explain the current distribution of a long-lived perennial plant, Succisa pratensis, in a rural landscape in southern Sweden by linking its population biology with documented changes in the landscape, using a dynamical, spatially explicit model incorporating population dynamics and spatial spreading of the plant. Changes in the landscape were inferred from historical maps (1850 and 1900) and aerial photographs (1945 and 2001).

   

  We tested whether predictions for the current species distribution are affected by assumptions about its early 19th century distribution, to determine whether recent history and current processes are dominant, and how past landscape changes determine current distributions.

   

  Initial conditions influence predictions of current distribution, suggesting that the current distribution still partly reflects the distribution of the species in the early 19th century. A period of 150 years is too short for Succisa to have spread extensively if dispersal parameters are given realistic values.

   

  Simulations in which present-day land-use patterns were imposed at earlier dates showed that changes in landscape structure over the past 175 years also had a strong effect on the present-day habitat occupancy and population sizes of Succisa.

   

  The dominant process for Succisanow is extinction from marginal habitats. It is therefore likely that the (relatively) high present-day occupation patterns are still due to much larger areas having been available in the past rather than to successful dispersal. Although the species has responded to landscape changes, there is little evidence of population sizes reaching equilibrium.

   

  Our approach shows that the wealth of landscape information available from historical maps can be linked with data on population biology by means of dynamical models that can make predictions about species dynamics.

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• The History (1620-2003) of Land Use, People and Livestock, and the Relationship to Present Plant Species Diversity in a Rural Landscape in Sweden

  2006. Anna Dahlström, Sara A. O. Cousins, Ove Eriksson. Environment and History 12, 191-212

  Artikel

  The traditional agriculture in Europe favoured numerous plant and animal species that are presently declining. Integrated studies based on various sources are needed in order to unravel the complex relationships between changing landscapes and biological diversity. The objectives of this study were to describe changes in land use during c. 350 years in a Swedish agricultural landscape in relation to changes in human population and livestock, and to analyse relationships between historical land use and present-day plant species diversity. There were only minor long-term changes in land use, population and livestock between 1640 and 1854 in the two studied hamlets, but detailed data 1620-41 showed a large short-term fluctuation in livestock numbers. After 1854 larger changes took place. Grasslands were cultivated and livestock composition changed. After 1932, livestock number decreased and most of the former grazed outland (areas located outside the fenced infields) turned into forest by natural succession. 7 per cent of the study area is still grazed semi-natural grassland. The highest plant species richness is today found on semi-natural grassland with a long continuity of grazing. The distribution of five target species suggests that previous land use still has an important effect today. The majority of their occurrences are remnant populations located in previous outland pastures which are today forests.

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• Plant species response to land-use change - Campanula rotundifolia, Primula veris and Rhinanthus minor

  2005. Regina Lindborg, Sara A. O. Cousins, Ove Eriksson. Ecography 28 (1), 29-36

  Artikel

  Land use change is a crucial driver behind species loss at the landscape scale. Hence, from a conservation perspective, species response to habitat degradation or improvement of habitat quality, is important to examine. By using indicator species it may be possible to monitor long-term survival of local populations associated with land use change. In this study we examined three potential indicator (response) species for species richness and composition in Scandinavian semi-natural grassland communities: Campanula rotundifolia, Primula veris and Rhinanthus minor. With field inventories and experiments we examined their response to present land use, habitat degradation and improvement of local habitat quality. At the time scale examined, C. rotundifolia was the only species responding to both habitat degradation and improvement of habitat quality. Neither R. minor nor P. veris responded positively to habitat improvements although both responded rapidly to direct negative changes in habitat quality. Even though C. rotundifolia responded quickly to habitat degradation, it did not disappear completely from the sites. Instead, the population structure changed in terms of decreased population size and flowering frequency. It also showed an ability to form remnant populations which may increase resilience of local habitats. Although P. veris and especially R. minor responded rapidly to negative environmental changes and may be useful as early indicators of land use change, it is desirable that indicators respond to both degradation and improvement of habitat quality. Thus, C. rotundifolia is a better response species for monitoring effects of land use change and conservation measures, provided that both local and regional population dynamics are monitored over a long time period.

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• Assessing changes in plant distribution patterns - indicator species versus plant functional types

  2004. Sara A. O. Cousins, Regina Lindborg. Ecological Indicators 4 (1), 17-27

  Artikel

  To meet conservation goals it is necessary to assess vegetation status and to be able to monitor effects of management and environmental change. In northern Europe grazed grasslands are one of the most threatened habitat in the rural landscape and thus in focus for conservation plans. At present managers use species indicator list to assess past and present management status of grassland and succession stages in particular, as well as effects of the environment. However, these indicators have rarely been scientifically tested. In this study we discuss if plant functional traits may be a key to select suitable indicator species for monitoring land-use change in Swedish rural landscape. The suitability of two possible monitoring tools: (i) plant species selected from functional traits (PFTs) and (ii) indicator species commonly used today to assess grassland management status, were tested along two gradients, a succession gradient and a wetness gradient. We found no association between successional change and plant functional traits, but a response in plant functional traits was found along the wetness gradient. However, the more common non-scientific indicator species responded fairly well to the varying gradient categories along both gradients. We believe that there is a need to further validate the ecological mechanisms behind the present-day indicators and to place them in a geographical context.

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• Modelling the effects of landscape pattern and grazing regimes on the persistence of plant species with high conservation value in grasslands in south-eastern Sweden

  2003. Sara A. O. Cousins, Sandra Lavorel, Ian Davies. Landscape Ecology 18 (3), 315-332

  Artikel

  Semi-natural grasslands in Sweden are threatened by land-use change and lack of management with attendant risk to their biodiversity. We present a model to explore the effects of grazing frequency and intensity on plant species persistence, and the relative effects of grassland size and pattern. We used a landscape modelling platform, LAMOS (LAndscape MOdelling Shell), to design a landscape model of vegetation dynamics incorporating the effects of local succession, dispersal and grazing disturbance. Five plant functional groups (PFG), representing various combinations of persistence and dispersal character, light requirements and disturbance responses, were defined to model species dynamics. Based on old cadastral maps three different landscapes were designed representing specific time-layers, i.e., a historical (17th to 18th century), a pre-modern (1940s) and a present-day landscape. Simulations showed that a threshold was crossed when grasslands decreased in area to about 10 - 30% of the modelled area, and as a consequence the biomass of grassland-specific PFGs was strongly reduced. These competition sensitive groups did not persist in the model even with intense grazing in the present-day landscape, where grasslands occupy 11% of the total area. However, all grassland species would have been able to persist in the historical landscape, where grasslands occupied 59% of the total area, even without grazing. Our results suggest that continuous but low-intensity grazing is more positive for grassland PFGs than discontinuous but highly intensive grazing. This effect was particularly strong when the frequency and/or intensity of grazing dropped below a threshold of 20%. Simulations using three landscape maps designed to explore effects of further fragmentation and habitat loss showed that the spatial pattern of remaining grasslands is important for the persistence of grassland-specific PFG. The model presented here is an advance towards more realistic grazing models to explore the effects of prescribed grazing and landscape fragmentation on the persistence species or plant functional groups.

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• Land-use history and fragmentation of traditionally managed grasslands in Scandinavia

  2002. Ove Eriksson, Sara A. O. Cousins, Hans Henrik Bruun. Journal of Vegetation Science 13 (5), 743-748

  Artikel

  Plants associated with traditional agricultural landscapes in northern Europe and Scandinavia are subjected to drastic habitat fragmentation. In this paper we discuss species response to fragmentation, against a background of vegetation and land-use history. Recent evidence suggests that grassland-forest mosaics have been prevalent long before the onset of human agriculture. We suggest that the creation of infield meadows and outland grazing (during the Iron Age) increased the amount and spatial predictability of grasslands, resulting in plant communities with exceptionally high species densities. Thus, distribution of plant species in the present-day landscape reflects historical land-use. This holds also when traditional management has ceased, due to a slow response by many species to abandonment and fragmentation. The distribution patterns are thus not in equilibrium with the present habitat distribution. Fragmentation influences remaining semi-natural grasslands such that species density is likely to decline as a result of local extinctions and invasion by habitat generalists. However, species that for a long time have been subjected to changing mosaic landscapes may be more resistant to fragmentation than is usually believed. Conservation should focus not only on 'hot-spots' with high species richness, but also consider species dynamics in a landscape context.

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• Reconstructing past land use and vegetation patterns using palaeogeographical and archaeological data: A focus on grasslands in Nynas by the Baltic Sea in south-eastern Sweden

  2002. Sara A. O. Cousins, Åsa Eriksson, Daniel Franzen. Landscape and Urban Planning 61 (1), 1-18

  Artikel

  Past landscape characteristics were reconstructed in Nynas, south-eastern Sweden, using geographical and archaeological data together with pollen stratigraphy and an existing shore displacement model, with the aim to explore the development of semi-natural grasslands in the area. A 2.3 m peat core was analysed and radiocarbon dated at three levels. The pollen stratigraphy was estimated to start at approximately 3800 C-14 years before present (BP), at the end of Late Neolithic. Human activities are evident, from both archaeological findings and pollen analysis, for more than 4000 years. Grazing is apparent, possibly more intense around 3200 C-14 years BP, 2500-2600 C-14 years BP, 2100-2200 C-14 years BP, and 1300/1400 C-14 years BP to present day. From 1900+/-80 C-14 years BP and onwards cultivation is intensified at the same time as spruce (Picea abies) expands. Maps on land-cover distribution in the late 17th century was used as a model for the utilisation of the landscape during the Iron Age. Land-covers on very thin soils were grazed and sometimes mown within the village boundaries, but they were also used for cultivation in narrow strips where bedrock is adjacent to clays. Till and varved glacial clays would have been used for cultivation. A reasonable estimation is that 10% of the study area could have been used for cultivation 1900 C-14 years BP, compared to 28% in the end of the 17th century. During the last century there has been a shift towards more arable fields and more forestry. There are 10% open or semi-open grassland left today, and 6% wooded grassland, compared with 47% open or semi-open grassland in the 17th century. Little more than half of the open grasslands are managed today, all by grazing. It is argued that encroachment of trees and shrubs on open or semi-open grasslands will not only reduce species richness in the landscape but also threaten parts of our cultural heritage.

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• The influence of management history and habitat on plant species richness in a rural hemiboreal landscape, Sweden

  2002. Sara A. O. Cousins, Ove Eriksson. Landscape Ecology 17 (6), 517-529

  Artikel

  We explored patterns of plant species richness at different spatial scales in 14 habitats in a Swedish rural landscape. Effects of physical conditions, and relationships between species richness and management history reaching back to the 17 (th) century were examined, using old cadastral maps and aerial photographs. The most species-rich habitats were dry open semi- natural grasslands, midfield islets and road verges. Alpha diversity (species richness within sites) was highest in habitats on dry substrates (excluding bedrock with sparse pines) and beta diversity (species richness among sites) was highest in moist to wet habitats. Alpha and beta components of species richness tended to be inversely related among habitats with similar species richness. Management history influenced diversity patterns. Areas managed as grasslands in the 17 th and 18 th century harboured more species than areas outside the villages. We also found significant relationships between species richness and soil type. Silt proved to be the most species- rich topsoil (10- 20 cm) in addition to thin soils top of on green- or limestone bedrock. The variation in species richness due to local relief or form of the site also showed significant relationships, where flat surfaces had the highest number of species. In contrast, no significant relationship was found between species richness and aspect. Our study suggests that present- day diversity patterns are much influenced by management history, and that small habitat, e. g., road verges and midfield islets, are important for maintaining species richness.

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• Analysis of land-cover transitions based on 17th and 18th century cadastral maps and aerial photographs

  2001. Sara A. O. Cousins. Landscape Ecology 16 (1), 41-54

  Artikel

  This paper explores the possibility of using non-geometric cadastral maps from the 17th and 18th century together with aerial photographs from 1945 and 1981 to analyse land-cover change in south-east Sweden. Habitats rich in plant species in the European rural landscape seem to be correlated with a long continuity of management. Accurate spatial data from historical data sources are fundamental to understand patterns of vegetation and biodiversity in the present-day landscape. However, traditional methods for rectification of non-geometric maps using corresponding points from orthophotos or modern maps are not satisfying, as internal inaccuracies will remain in the maps. This study presents a method to rectify the maps by local warping, thereby eliminating geometrical irregularities. Further, the land-cover changes were calculated and presented as transition matrices. The extent of arable fields and grasslands were analysed in relation to soil characteristics and continuity of management. The results show a dynamic relation between grassland and arable field, albeit the overall proportions remained almost the same between 17th and 18th centuries: 60% grassland to 32% arable field. The most substantial changes in land-cover were prior to 1945. Today there is 18% grasslands left in the study area, while 56% of the land-cover is arable field. Approximately 8% of present-day land-cover is semi-natural grassland 300 years of age or more. Compared to 300 years ago there is only 1% grassland left on peat and 2% on clay. In contrast, grassland covers associated with bare bedrock have been fairly stable in size. All semi-natural grasslands with a long continuity of management were situated on shallow soils, less than 50 cm depth. The major conclusions from this study are that (i) correctly rectified, old maps are very useful to address questions of land-cover changes in historical time, (ii) general trends in land use over 300 years in this hemi-boreal landscape seem to underestimate the full dynamics of land use change, and (iii) only a small proportion of the semi-natural grassland area had a 300 year continuity of management.

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• A methodological study for biotope and landscape mapping based on CIR aerial photographs

  1998. Sara A. O. Cousins, Margareta Ihse. Landscape and Urban Planning 41 (3-4), 183-192

  Artikel

  In this paper, we present a method for base-line mapping of biotope and landscape elements in the rural Swedish agricultural landscape. The overall goal is to elaborate a classification system for a national landscape monitoring program, based on interpretation of existing colour infrared (CIR) aerial photographs at the scale 1:30000, and including a field control. The classification system developed was tested by mapping landscape elements in strategically selected test areas, and it is assessed with respect to interpretation accuracy. The landscape elements, mapped separately as patches, lines and points, are significant for the biodiversity on landscape level, and are susceptible to change. The classification system is based on a hierarchical approach in five levels, with regard to land use and management, nature type and succession stage, moisture, physiognomy, vegetation cover and plant species. By using the method and the suggested classification system, a base-line mapping can be done very quickly and accurately. The mapping rate is 1.4-2.8 km(2)/h and the interpretation accuracy is 95-99%.

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