Rugged, hilly landscapes with a range of different habitat types can help maintain more stable butterfly populations and thus aid their conservation, according to new findings published in the journal Ecology Letters.
The research, carried out by scientists from the Centre for Ecology & Hydrology, Butterfly Conservation and the University of York, has implications for how we might design and manage landscapes better to help conserve species.
The scientists used UK Land Cover Map data (from satellite images) to collect information on the topography and diversity of habitats in the landscape. They found that sites with a greater diversity of habitat types (eg woodland, grassland, heathland) and more varied terrain tended to have butterfly populations that were more stable over time.
These more diverse landscapes may provide a broader range of environments, and hence resources and microclimates, which can buffer species against a variety of climatic extremes and potential population decline in difficult years.
"More stable insect populations are better for conservation because it means that, in years with extreme weather, populations are less likely to go extinct."
Tom Oliver, Centre for Ecology & Hydrology
Thirty-five British butterfly species were included in the analysis using records collected by volunteers of the UK Butterfly Monitoring Scheme from 166 transect sites across the UK. The research team compared the stability of butterfly populations over an 11-year period with the diversity of habitats in the surrounding landscape up to 5km from monitored sites.
They concluded that landscapes with a greater range of habitats harboured more stable butterfly populations. In addition, landscapes with a greater range of topographic aspect (eg north, south, east and west facing slopes) were also better for the insects.
The study's lead author, Dr Tom Oliver from the Centre for Ecology & Hydrology, said their research showed that populations of butterfly species such as the Brown Argus (Aricia agestis) and the Dingy Skipper ( Erynnis tages) were more stable when located in hilly landscapes with a range of habitat types.
"More stable insect populations are better for conservation because it means that, in years with extreme weather, for example, drought years, populations are less likely to go extinct," he explained.
A surprising result from the study was that, for some butterfly species, the diversity of habitats up to 5km away from monitored sites affected the butterfly populations. This could have implications for conservationists directing resources to some local sites without considering the wider landscape context.
Co-author Dr Tom Brereton, Head of Monitoring at Butterfly Conservation, said the results highlighted the importance of taking a landscape perspective for species conservation.
The researchers hope that in the future it may be possible to design landscapes that are more effective at conserving species. Co-author Dr David Roy, from the Centre for Ecology & Hydrology, said, "With a rapidly changing climate we need our landscapes to support biodiversity as well as provide other ecosystem services such as food production and clean water.
"Using remotely-sensed land cover data from satellites to design landscapes may help us to achieve the right balance," he added.
The research is published in the journal Ecology Letters. The full paper reference is:
Tom Oliver, David B. Roy, Jane K. Hill, Tom Brereton and Chris D. Thomas (2010) Heterogeneous landscapes promote population stability. Ecology Letters.
Land Cover Map 2000 is a digital map made by CEH from analysis of data from Earth observation satellites. The satellite sensors record spectral reflectances from the Earth's surface, on a grid of approximately 25m x 25m cells or "pixels". The data portray a landscape structure with land parcels and dissected patterns of semi-natural vegetation. Summer and winter images were used to help to distinguish bare and urban areas from rotation arable crops, and these in turn from permanent vegetation, whether evergreen or deciduous.
Related CEH news stories and links
Butterflies use more ‘environmental space’ in warmer areas - 23 September 2009
Details of CEH's Biodiversity science programme