Species ecology and the impacts of bioenergy crops: an assessment approach with four example farmland bird species

Abstract

The cultivation of energy crops can cause land-use conflicts, including loss of biodiversity in farmlands. In our study, we focus on farmland birds and analyse whether the impacts of such bioenergy activities differ for bird species with different ecology. We do this by comparing the impacts on four example species; skylark (Alauda arvensis), yellow wagtail (Motacilla flava), corn bunting (Miliaria calandra) and northern lapwing (Vanellus vanellus). We used a spatially explicit ecological model, which combines three simplified crop selection criteria (suitability for nesting, suitability for foraging, spatial heterogeneity) that differ between the selected species. We used the model to investigate change in breeding pair density between a baseline and several bioenergy scenarios that differ in intensity and spatial agglomeration. We subsequently simulated scenarios with potential positive habitat effects (maintenance of 10% set-aside or 10% alfalfa) as well as spatial effects (increased crop diversity and reduction of field size) as mitigation strategies to increase the breeding pair density. The four species responded to the bioenergy scenarios with a decrease in breeding pair density that can be divided into roughly three levels: strong (skylark), intermediate (yellow wagtail and corn bunting) and no response (northern lapwing). The intensity of the response depended on the bioenergy scenario. The decrease in breeding pair density under the least intensive bioenergy scenario could be fully mitigated for all the considered bird species through 10% set-aside. However, with increasing dominance or spatial agglomeration of a single energy crop (e.g., maize), impacts cannot or hardly be mitigated and the effectiveness of the mitigation strategies becomes increasingly more dependent on the ecological preferences of the bird species.