The trait-based response of woodland beetle communities to landscape heterogeneity and change along an urban gradient

The heterogeneity of European agricultural landscapes is known to influence species distributions and the relative importance of landscape composition and configuration varies by taxonomic group (Schweiger et al. 2005; Neumann et al. 2015, 2016). Historical landscapes can also better explain the distribution of current species populations than contemporary landscapes, suggesting that the effects of landscape change can involve a time lag, resulting in an extinction debt (Kuussaari et al. 2009).

Woodland loss, fragmentation and changes to the surrounding matrix may all reduce functional connectivity for some species, whether the changes are due to agricultural practice or urbanisation. This study aims to determine whether species communities in urban woodland fragments and those in woodlands dominated by agriculture respond similarly to changes in landscape heterogeneity. We take a wildlife ecology approach; collecting field data on a range of ground-dwelling beetles (Carabidae and Staphylinidae) and using species traits such as dispersal ability to assess the impact of changes in connectivity (Barbaro & van Halder 2009).

Fifty-six woodland patches were selected along an urban-rural gradient of 0 to 15km from the centre of Reading, an urban centre in southern England of roughly 60km2. A 500m radius landscape was established around the centre point of each patch. Beetles were sampled using pitfall traps in summer 2015. The response of species with different life-history traits to landscape composition and configuration in a detailed modern landscape model (based on high-resolution landuse data and aerial imagery) and to a simplified model of wooded and urban habitat changes (Fig. 1) for three time periods (1880s, 1930s and present day) will be assessed using Canonical Correspondence Analysis.

Preliminary results based on contemporary landscape composition show that small, generalist carabids are more frequent in small or urban woodland patches. Large, flightless species are more common in large, rural woodlands. These results are consistent with previous studies of carabid communities in an urban landscape context (Sadler et al. 2006; Magura, Lovei & Tothmeresz 2008), illustrating the potential utility of our study in extending this question to other taxa. It is anticipated that results of the historical analysis will infer an extinction debt for slow-dispersing woodland species, whilst increases in arable and urban landcover over the time period may benefit mobile generalists.

There will continue to be conflicts about how to use and manage land for urban areas, agricultural productivity and biodiversity and creating a functional network demands an understanding of exactly how landscape change impacts on different species. Comparing the responses of multiple taxa with different functional traits to representations of contemporary and historical landscapes will enable us to assess how habitat networks can best be implemented to enhance biodiversity and other ecosystem services.