Biodiversity in cultural landscapes: influence of land use intensity on bird assemblages

CONTEXT: Land use changes and intensification have been amongst the major causes of the on-going biodiversity decline in Europe. A better understanding and description of how different levels of land use intensity affect biodiversity can support the planning and evaluation of policy measures. OBJECTIVES: Our study investigates how land use-related landscape characteristics affect bird diversity, considering different spatial scales and species groups with characteristic habitat use. METHODS: We used breeding bird census data from 2693 observation points along 206 transects and applied a random effects hurdle model to describe the influence of the landscape characteristics altitude, forest proportion, patch density, land cover diversity, and land use intensity on avian species richness. RESULTS: Land use intensity and related landscape characteristics formed an important explanatory variable for bird richness. Increasing land use intensity was accompanied by a decrease in bird species richness. While forest bird richness decreased with a decreasing amount of forest cover, farmland species richness increased. This led to a bird diversity peak in extensively used semi-open landscapes. The influence of land cover diversity on species richness was small. Increasing patch density had positive effects on forest birds, but affected farm birds negatively. The strongest correlation between land use-based indicators and bird diversity was determined using spatial indicators at a close range around observation points (100–500 m radius). CONCLUSIONS: Our results assist interpretation of the Pan-European Common Bird Indices and emphasize the importance of using multifaceted and thoroughly selected indicators in the context of biodiversity monitoring and decision-making support.