Courses

I am not teaching very much during the time I serve as head of department, other than a few presentations at different courses.

Master students

I supervise master students regularly. If you are a student: check my research projects and see if you get inspired to do a project on landscape ecology in Sweden or perhaps in Ethiopia.

My current research is mostly focusing on

1) Variation in local climate and how that affects the performance and distribution of plants (both vascular plants, bryophytes and lichens)

Under this theme I do research with support primarily from Formas and the Bolin Centre for Climate Research at Stockholm University (see link). 

See more about the research projects, involved people and news on www.hylanderecology.com.

2) Water, biodiversity and ecosystem services across Ethiopian agroecosystems

I have much involvement in Ethiopia since many years now. Right now I have an interdisciplinary project focusing on water in the landscape and it variable use, quality, biodiversity content across land-use gradients. Moreover, I am heavily involved in other projects on biodiversity, coffee diseases and climate in coffee agroforestry togheter wtih Prof. Ayco Tack who is the PI of those projects.  

See more about the research projects, involved people and news on www.hylanderecology.com.

A selection from Stockholm University publication database

• Lessons from Ethiopian coffee landscapes for global conservation in a post-wild world

  2024. Kristoffer Hylander (et al.). Communications Biology 7

  Article

  The reality for conservation of biodiversity across our planet is that all ecosystems are modified by humans in some way or another. Thus, biodiversity conservation needs to be implemented in multifunctional landscapes. In this paper we use a fascinating coffee-dominated landscape in southwest Ethiopia as our lens to derive general lessons for biodiversity conservation in a post-wild world. Considering a hierarchy of scales from genes to multi-species interactions and social-ecological system contexts, we focus on (i) threats to the genetic diversity of crop wild relatives, (ii) the mechanisms behind trade-offs between biodiversity and agricultural yields, (iii) underexplored species interactions suppressing pest and disease levels, (iv) how the interactions of climate change and land-use change sometimes provide opportunities for restoration, and finally, (v) how to work closely with stakeholders to identify scenarios for sustainable development. The story on how the ecology and evolution of coffee within its indigenous distribution shape biodiversity conservation from genes to social-ecological systems can inspire us to view other landscapes with fresh eyes. The ubiquitous presence of human-nature interactions demands proactive, creative solutions to foster biodiversity conservation not only in remote protected areas but across entire landscapes inhabited by people.

  Read more about Lessons from Ethiopian coffee landscapes for global conservation in a post-wild world

• Microclimate, an important part of ecology and biogeography

  2024. Julia Kemppinen (et al.). Global Ecology and Biogeography 33 (6), e13834

  Article

  Brief introduction: What are microclimates and why are they important? Microclimate science has developed into a global discipline. Microclimate science is increasingly used to understand and mitigate climate and biodiversity shifts. Here, we provide an overview of the current status of microclimate ecology and biogeography in terrestrial ecosystems, and where this field is heading next.

  Microclimate investigations in ecology and biogeography: We highlight the latest research on interactions between microclimates and organisms, including how microclimates influence individuals, and through them populations, communities and entire ecosystems and their processes. We also briefly discuss recent research on how organisms shape microclimates from the tropics to the poles.

  Microclimate applications in ecosystem management: Microclimates are also important in ecosystem management under climate change. We showcase new research in microclimate management with examples from biodiversity conservation, forestry and urban ecology. We discuss the importance of microrefugia in conservation and how to promote microclimate heterogeneity.

  Methods for microclimate science: We showcase the recent advances in data acquisition, such as novel field sensors and remote sensing methods. We discuss microclimate modelling, mapping and data processing, including accessibility of modelling tools, advantages of mechanistic and statistical modelling and solutions for computational challenges that have pushed the state-of-the-art of the field.

  What's next? We identify major knowledge gaps that need to be filled for further advancing microclimate investigations, applications and methods. These gaps include spatiotemporal scaling of microclimate data, mismatches between macroclimate and microclimate in predicting responses of organisms to climate change, and the need for more evidence on the outcomes of microclimate management.

  Read more about Microclimate, an important part of ecology and biogeography

• Climate adaptation of biodiversity conservation in managed forest landscapes: [Adaptación Climática de la Conservación de la Biodiversidad en Paisajes Forestales Gestionados]

  2022. Kristoffer Hylander (et al.). Conservation Biology 36 (3)

  Article

  Conservation of biodiversity in managed forest landscapes needs to be complemented with new approaches given the threat from rapid climate change. Most frameworks for adaptation of biodiversity conservation to climate change include two major strategies. The first is the resistance strategy, which focuses on actions to increase the capacity of species and communities to resist change. The second is the transformation strategy and includes actions that ease the transformation of communities to a set of species that are well adapted to the novel environmental conditions. We suggest a number of concrete actions policy makers and managers can take. Under the resistance strategy, five tools are introduced, including: identifying and protecting forest climate refugia with cold-favored species; reducing the effects of drought by protecting the hydrological network; and actively removing competitors when they threaten cold-favored species. Under the transformation strategy, we suggest three tools, including: enhancing conditions for forest species favored by the new climate, but currently disfavored by forest management, by planting them at suitable sites outside their main range; and increasing connectivity across the landscape to enhance the expansion of warm-favored species to sites that have become suitable. Finally, we suggest applying a landscape perspective and simultaneously managing for both retreating and expanding species. The two different strategies (resistance and transformation) should be seen as complementary ways to maintain a rich biodiversity in future forest ecosystems. 

  Read more about Climate adaptation of biodiversity conservation in managed forest landscapes

• Changes in forest structure drive temperature preferences of boreal understorey plant communities

  2022. Ditte Marie Christiansen (et al.). Journal of Ecology 110 (3), 631-643

  Article

  1. The local climate in forest understories can deviate substantially from ambient conditions. Moreover, forest microclimates are often characterized by cyclic changes driven by management activities such as clear-cutting and subsequent planting. To understand how and why understorey plant communities change, both ambient climate change and temporal variation in forest structure have to be considered.
  2. We used inventories from 11,436 productive forest sites in Sweden repeated every 10th year 1993–2017 to examine how variation in forest structure influences changes in the average value of minimum and maximum temperature preferences of all species in a community, that is, community temperature indices (CTIs). We then evaluated to what extent these changes were driven by local extinctions and colonizations, respectively, and to what extent the difference in CTI value between two inventories was related to changes in forest density and in macroclimate. Lastly, we tested whether effects on CTI change by these two drivers were modified by topography, soil moisture and tree species composition.
  3. CTI values of the understorey plant communities increased after clear-cutting, and decreased during periods when the forest grew denser. During the period immediately after clear-cutting, changes were predominately driven by colonizations of species with a preference for higher temperatures. During the forest regeneration phase, both colonizations by species preferring lower temperatures and local extinctions of species preferring higher temperatures increased. The change in understorey CTI over 10-year periods was explained more by changes in forest density, than by changes in macroclimate. Soil moisture, topography and forest tree species composition modified to some extent the effects of changes in forest density and in macroclimate on understorey CTI values.
  4. Synthesis. Via stand manipulation, forest management impacts the effects of regional climate on understorey plant communities. This implies that forest management by creating denser stands locally even can counterbalance the effects of regional changes in climate. Consequently, interpretations of changes in the mean temperature preference of species in forest understorey communities should take forest management regimes into account.

  Read more about Changes in forest structure drive temperature preferences of boreal understorey plant communities

• Forest microclimates and climate change

  2021. Pieter De Frenne (et al.). Global Change Biology 27 (11), 2279-2297

  Article

  Forest microclimates contrast strongly with the climate outside forests. To fully understand and better predict how forests' biodiversity and functions relate to climate and climate change, microclimates need to be integrated into ecological research. Despite the potentially broad impact of microclimates on the response of forest ecosystems to global change, our understanding of how microclimates within and below tree canopies modulate biotic responses to global change at the species, community and ecosystem level is still limited. Here, we review how spatial and temporal variation in forest microclimates result from an interplay of forest features, local water balance, topography and landscape composition. We first stress and exemplify the importance of considering forest microclimates to understand variation in biodiversity and ecosystem functions across forest landscapes. Next, we explain how macroclimate warming (of the free atmosphere) can affect microclimates, and vice versa, via interactions with land-use changes across different biomes. Finally, we perform a priority ranking of future research avenues at the interface of microclimate ecology and global change biology, with a specific focus on three key themes: (1) disentangling the abiotic and biotic drivers and feedbacks of forest microclimates; (2) global and regional mapping and predictions of forest microclimates; and (3) the impacts of microclimate on forest biodiversity and ecosystem functioning in the face of climate change. The availability of microclimatic data will significantly increase in the coming decades, characterizing climate variability at unprecedented spatial and temporal scales relevant to biological processes in forests. This will revolutionize our understanding of the dynamics, drivers and implications of forest microclimates on biodiversity and ecological functions, and the impacts of global changes. In order to support the sustainable use of forests and to secure their biodiversity and ecosystem services for future generations, microclimates cannot be ignored.

  Read more about Forest microclimates and climate change

• Temporal dynamics and biocontrol potential of a hyperparasite on coffee leaf rust across a landscape in Arabica coffee's native range

  2021. Beyene Zewdie (et al.). Agriculture, Ecosystems & Environment 311

  Article

  Agroforestry systems can provide habitats for a rich biodiversity including multitrophic interactions, which presents opportunities to develop natural pest control. Shade coffee systems in several coffee growing areas of the world host such unique habitats where pests and their natural enemies interact. One of the major global challenges for coffee production, coffee leaf rust caused by the fungal pathogen Hemileia vastatrix is attacked by the fungal hyperparasite, Lecanicillium lecanii. However, we lack insights in the dynamics and biocontrol potential of the hyperparasite on coffee leaf rust from landscapes in Arabica coffee's native range. To understand the temporal dynamics across landscapes and environmental drivers of the rust and hyperparasite, and the potential for biocontrol of the rust by the hyperparasite, we studied the rust and hyperparasite during the dry and wet seasons for three consecutive years at 60 sites across a gradient of coffee management in southwestern Ethiopia. We found that coffee leaf rust was more severe during the dry season, whereas the hyperparasite was more severe during the wet season in two out of three years. The rust growth rate from the wet to the dry season transition was negatively related to the hyperparasite index during the wet season, implying a potential top-down control. Coffee leaf rust was generally more severe at lower altitudes in the dry season, whereas the hyperparasite was more severe at high altitude. The rust incidence increased with management intensity, while the hyperparasite was more common under less intensive management. This study could be interesting in that it represents a landscape where Arabica coffee originated and the rust and hyperparasite might have a long co-evolutionary history. Our findings highlight the potential of the hyperparasite to suppress the rust's growth rate from the wet to dry season transition when the rust severity could otherwise be at its peak. We show that less intensively managed landscapes with dense shade levels are likely to increase hyperparasite abundance and result in an improved top-down control of the rust. However, more detailed knowledge is needed on the interaction of these species to assess its importance for reducing rust induced yield losses or the risk of rust outbreaks.

  Read more about Temporal dynamics and biocontrol potential of a hyperparasite on coffee leaf rust across a landscape in Arabica coffee's native range

• Hiding from the climate

  2020. Caroline Greiser (et al.). Global Change Biology

  Article

  Climate warming is likely to shift the range margins of species poleward, but fine-scale temperature differences near the ground (microclimates) may modify these range shifts. For example, cold-adapted species may survive in microrefugia when the climate gets warmer. However, it is still largely unknown to what extent cold microclimates govern the local persistence of populations at their warm range margin. We located 99 microrefugia, defined as sites with edge populations of 12 widespread boreal forest understory species (vascular plants, mosses, liverworts and lichens) in an area of ca. 24,000 km(2) along the species' southern range margin in central Sweden. Within each population, a logger measured temperature eight times per day during one full year. Using univariate and multivariate analyses, we examined the differences of the populations' microclimates with the mean and range of microclimates in the landscape, and identified the typical climate, vegetation and topographic features of these habitats. Comparison sites were drawn from another logger data set (n = 110), and from high-resolution microclimate maps. The microrefugia were mainly places characterized by lower summer and autumn maximum temperatures, late snow melt dates and high climate stability. Microrefugia also had higher forest basal area and lower solar radiation in spring and autumn than the landscape average. Although there were common trends across northern species in how microrefugia differed from the landscape average, there were also interspecific differences and some species contributed more than others to the overall results. Our findings provide biologically meaningful criteria to locate and spatially predict potential climate microrefugia in the boreal forest. This opens up the opportunity to protect valuable sites, and adapt forest management, for example, by keeping old-growth forests at topographically shaded sites. These measures may help to mitigate the loss of genetic and species diversity caused by rear-edge contractions in a warmer climate.

  Read more about Hiding from the climate

• Calcicolous plants colonize limed mires after long-distance dispersal

  2018. Niklas Lonnell, Kristoffer Hylander. Journal of Biogeography 45 (4), 885-894

  Article

  Aim: Dispersal range is a key factor for understanding species' persistence in dynamic landscapes. However, dispersal, especially over long distances, is inherently difficult to study. Making use of a unique system of anthropogenically disturbed, geographically isolated mires, we assessed dispersal ranges for a group of plants restricted to wet calcareous conditions via empirical studies of colonization patterns. We hypothesized that more species would have colonized the less isolated mires and that colonization frequencies would be related to traits influencing propagule pressure. Location: Sweden. Taxon: Calcicolous vascular plants and bryophytes. Methods: The study system consisted of 52 acidic mires that had acquired a high pH through active liming by the Swedish government during the past two decades. These conditions killed off mat-forming peat mosses, rendering the mires open to colonization by other species. In each mire, we recorded the presence of rich fen plant species typically found in high pH wet soils throughout the country. We used citizen science-collected records of occurrences of obligate-rich fen species surrounding each mire to examine the likely dispersal distances that were involved in creating the colonization patterns. Results: A lower proportion of vascular plants than bryophytes from their respective species pools colonized the limed mires (27% vs. 67%, p = .001). The number of colonized rich fen species per site was 0-6 for vascular plants and 10-31 for bryophytes, and was positively related to potential diaspore sources >20km from the mires (p = .026 and p = .012, respectively). The proportion of colonized mires was positively related to the species' regional frequency, but not with their diaspores' terminal velocity. Main conclusions: Many bryophyte species can effectively disperse over long distances (tens of kilometres) and variation among species in total diaspore production seems to be an important regulator of colonization across landscapes, for both vascular plants and bryophytes, in communities that are open to colonization.

  Read more about Calcicolous plants colonize limed mires after long-distance dispersal

• Waiving the extinction debt

  2017. Kristoffer Hylander, Sileshi Nemomissa. Diversity & distributions 23 (8), 888-897

  Article

  AimLocal extinction after habitat modifications is often delayed, leading to an extinction debt. Our first aim was to develop a conceptual model for natural and human-mediated habitat improvements after a disturbance that may waive part of the predicted extinction debt. Second, we wanted to test this model on the distribution of epiphytic plants on trees that had been isolated in the agricultural matrix after forest clearing, around which coffee subsequently had been planted with a possible improvement of the microclimate. LocationBonga, Southern Nations, Nationalities and Peoples Region (SNNPR), Ethiopia. MethodsWe studied 50 trees that had been isolated for periods ranging from a few years to half a century after clearing. The trees were now located in the agricultural landscape at different distances from intact Afromontane forests. Fourteen trees in the forests were used as references. Each tree was inventoried for all vascular epiphytic plants, mosses and liverworts. ResultsTime since clearance had a direct negative effect on number of forest specialist species via delayed extinctions and the detected large extinction debt of both bryophytes and vascular plants continued to be paid over several decades. However, time since clearance had an indirect positive effect on number of forest indicator species via the reappearance of shade from coffee planted surrounding the trees, even if the waiving effect on the extinction debt was rather small. Additionally, trees at further distances from the forest edge had fewer forest-associated species. Main conclusionsOur results show that the ability of agroecological landscapes to foster forest biodiversity may be overestimated if meta-community processes over time and space are not taken into account. However, the possibility of initiating counteracting processes that modify the level of expected local extinctions should be evaluated more often to find ways of improving conditions for biodiversity in human-modified landscapes.

  Read more about Waiving the extinction debt

• Fine-grain, large-domain climate models based on climate station and comprehensive topographic information improve microrefugia detection

  2017. Eric Meineri, Kristoffer Hylander. Ecography 40 (8), 1003-1013

  Article

  Large-domain species distribution models (SDMs) fail to identify microrefugia, as they are based on climate estimates that are either too coarse or that ignore relevant topographic climate-forcing factors. Climate station data are considered inadequate to produce such estimates, a viewpoint we challenge here. Using climate stations and topographic data, we developed three sets of large-domain (450 000 km(2)), fine-grain (50m) temperature grids accounting for different levels of topographic complexity. Using these fine-grain grids and the Worldclim data, we fitted SDMs for 78 alpine species over Sweden, and assessed over-versus underestimations of local extinction and area of microrefugia by comparing modelled distributions at species' rear edges. Accounting for well-known topographic climate-forcing factors improved our ability to model fine-scale climate, despite using only climate station data. This approach captured the effect of cool air pooling, distance to sea, and relative humidity on local-scale temperature, but the effect of solar radiation could not be accurately accounted for. Predicted extinction rate decreased with increasing spatial resolution of the climate models and with increasing number of topographic climate-forcing factors accounted for. About half of the microrefugia detected in the most topographically complete models were not detected in the coarser SDMs and in the models calibrated from climate variables extracted from elevation only. Although major limitations remain, climate station data can potentially be used to produce fine-grain topoclimate grids, opening up the opportunity to model local-scale ecological processes over large domains. Accounting for the topographic complexity encountered within landscapes permits the detection of microrefugia that would otherwise remain undetected. Topographic heterogeneity is likely to have a massive impact on species persistence, and should be included in studies on the effects of climate change.

  Read more about Fine-grain, large-domain climate models based on climate station and comprehensive topographic information improve microrefugia detection

• Bryophytes in Forest Ecosystems

  2015. Nicole J. Fenton, Kristoffer Hylander, Emma J. Pharo. Routledge Handbook of Forest Ecology, 239-249

  Chapter

  Read more about Bryophytes in Forest Ecosystems

• The mechanisms causing extinction debts

  2013. Kristoffer Hylander, Johan Ehrlen. Trends in Ecology & Evolution 28 (6), 341-346

  Article

  Extinction debts can result from many types of habitat changes involving mechanisms other than metapopulation processes. This is a fact that most recent literature on extinction debts pays little attention to. We argue that extinction debts can arise because (i) individuals survive in resistant life-cycle stages long after habitat quality change, (ii) stochastic extinctions of populations that have become small are not immediate, and (iii) metapopulations survive long after that connectivity has decreased if colonization-extinction dynamics is slow. A failure to distinguish between these different mechanisms and to simultaneously consider both the size of the extinction debt and the relaxation time hampers our understanding of how extinction debts arise and our ability to prevent ultimate extinctions.

  Read more about The mechanisms causing extinction debts

Show all publications by Kristoffer Hylander at Stockholm University