I urval från Stockholms universitets publikationsdatabas

• European Union tree density limits do not reflect bat diversity in wood-pastures

  2017. Heather Wood, Regina Lindborg, Simon Jakobsson. Biological Conservation 210, 60-71

  Artikel

  The European Union's Common Agricultural Policy (CAP) recommends subsidies are only granted for wood-pastures with < 100 trees/ha. This guidance exists despite these habitats being among the most biodiverse in boreal Europe and currently under threat due to land conversion. Bats are important bio-indicators of agricultural landscapes, but bat diversity has not explicitly been studied in relation to this policy. We investigate how bat activity, foraging, species richness and functional groups are affected in twenty-six wood-pastures along a gradient of tree density, from open to dense. In parallel, open fields and deciduous forests were sampled and the effect of the surrounding landscape configuration was explored. Our results show a consistent increase in total bat activity, foraging activity and species richness within wood-pastures along the tree density gradient. We find optimal tree densities within wood-pastures are higher than values reported in previous studies, and suggest thresholds might depend on the landscape context. Shrub density was a strong predictor of total bat activity and foraging; whilst structural variation of tree size in wood-pastures was most strongly correlated with species richness. We show that wood-pastures are an important habitat and in comparison to forests they contribute to higher bat species richness and activity levels. Interestingly, higher activity levels of forest feeding specialists were observed in wood-pastures compared to forests. At the landscape level, amount of water in the landscape was the strongest predictor of bat activity whilst deciduous forest mostly influenced foraging activity. This study demonstrates that tree density within wood-pastures is not a limiting factor of bat activity and foraging and that other habitat and landscape parameters are important. Thereby focusing solely on tree density limits will not help to promote the ecological requirements for bats. Instead we suggest that a results based approach to CAP payments would be preferable.

  Läs mer om European Union tree density limits do not reflect bat diversity in wood-pastures

• HistMapR

  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.

  Läs mer om HistMapR

• Contrasting multi-taxa functional diversity patterns along vegetation structure gradients of woody pastures

  2020. Simon Jakobsson (et al.). Biodiversity and Conservation 29, 3551-3572

  Artikel

  Woody pastures represent keystone habitats for biodiversity in agricultural landscapes, contributing to increased resource availability, landscape heterogeneity and structural variability. High taxonomic diversity is closely linked to vegetation structure in woody pastures, but examining functional characteristics of species assemblages can shed more light on the ecological mechanisms driving divergent responses to habitat characteristics and help guide good management practices. To this end, we use a multi-taxa approach to investigate how plant, bat and bird taxonomic and functional diversity are affected by pasture tree and shrub density, structural complexity and proximate forest cover in southern Sweden. In particular, we use a trait exclusion approach to estimate the sensitivity of diversity-environment relationships to specific traits. We found little congruence between corresponding diversity metrics across taxa. Bird species richness responded stronger to environmental variables than functional diversity metrics, whereas the functional response to the environment was stronger than the taxonomic response among plants and bats. While increasing tree densities increased the taxonomic diversity of all three taxa, a simultaneous functional response was only evident for plants. Contrasting measures of vegetation structure affected different aspects of functional diversity across taxa, driven by different traits. For plants and birds, traits linked to resource use contributed particularly to the functional response, whereas body mass had stronger influence on bat functional diversity metrics. Multi-taxa functional approaches are essential to understand the effects of woody pasture structural attributes on biodiversity, and ultimately inform management guidelines to preserve the biological values in woody pastures.

  Läs mer om Contrasting multi-taxa functional diversity patterns along vegetation structure gradients of woody pastures

• 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

• 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

• Bats at northern latitudes: The influence of habitat and climate

  2024. Heather Wood.

  Avhandling (Dok)

  Globally, habitat change is one of the major drivers of biodiversity loss. Similar changes have occurred in Sweden over the past 150 years resulting in loss of habitat complexity at local and landscape scales.  In parallel, the climate is changing, with increasing air temperatures in the past 100 years. This changing climate will likely have knock-on effects on habitats and their microclimates.  Bats are often considered good indicators of environmental change. However, many bat species are declining globally with north European populations considered the most at risk due to climate change. The effects of habitat and climate change on bats are wide ranging and include loss of foraging habitat, impacts to roost locations, morphological changes and effects on their insect prey. In this thesis I identify how habitat and climate influence bat populations in Sweden, at multiple spatial and temporal scales.  Due to the complex nature of these drivers a multi-method approach was used, across a long latitudinal gradient in Sweden. To investigate the drivers of bat morphological change I analysed museum specimens over a 180-year time period together with historical maps, land-use statistics, and temperature data. To understand how habitat complexity at local and landscape scales influences bat activity, I monitored bats acoustically, sampled prey abundance and measured microclimate in a study focusing on forest borders. I also used a citizen science project to investigate bat diet and the local and landscape drivers of roost selection. I found no effect of climate change on bat morphology but jaw size changed over time in two bat species, with increasing jaw size in one species and decreasing in the other. In terms of microclimate, humidity was a strong driver of bat activity. As for effects of landscape level habitat, forest cover influenced wing morphology with bats having shorter, broader wings in more forested landscapes. Furthermore, area of deciduous forest had a positive effect on bat activity, roost selection and abundance of bat prey. At the local-scale forest structural complexity was important for bat activity but not for their insect prey. I also found high dietary overlap in the two most common species (Eptesicus nilssonii and Pipistrellus pygmaeus).  These findings highlight the need to maintain and increase deciduous forest cover and structurally complex forest borders within heterogenous habitats at local and landscape scales to meet the ecological needs of bats and their prey and ensure their conservation in the future.

  Läs mer om Bats at northern latitudes

Visa alla publikationer av Heather Wood vid Stockholms universitet