Grass buffer strips benefit invertebrate and breeding skylark numbers in a heterogeneous agricultural landscape

摘要

The loss of non-crop habitat is often suggested to be a key driver of biodiversity decline on arable land. Grass buffer strips on cereal field edges, to reduce erosion and agro-chemical runoff into surface water, could be useful to mitigate this diversity loss as they are often assumed to provide refuge and food for invertebrates, small mammals and birds. Evidence for this idea is, however, scarce and it remains unclear whether densely vegetated buffer strips benefit biodiversity in structurally complex landscapes of Northern Europe. Here, we examined whether buffer strips affected breeding skylark Alauda avensis numbers and its main food supply (i.e. beetles Coleoptera and spiders Arachnida) on cereal fields in a heterogeneous agricultural landscape of south-central Sweden. We also examined whether buffer strip effects on skylark density depended on seasonal sward height differences between sowing regimes (spring- vs. autumn-sown) as they presumably influence seasonal invertebrate accessibility. Fields with buffer strips supported on average 0.51pl0.26 more skylark territories per hectare up to 100m into the field and boosted invertebrate activity densities compared to fields without buffer strips. These effects were most apparent early in spring, but persisted throughout the sampling period, and were similar among spring and autumn sown fields. Thus, our results provide evidence to suggest that buffer strips target multiple environmental objectives on cereal fields in heterogeneous farmland. Future research should work to identify buffer strip management practices that further increase their value to biodiversity at the local scale, and investigate how they affect farmland biodiversity in different landscape types at larger spatial scales for more efficient implementation across Europe.