Preventing biotic homogenization of farmland bird communities: The role of High Nature Value farmland

High Nature Value (HNV) farmlands are expected to support high levels of biological diversity and may have a relevant role in driving biodiversity dynamics and particularly refraining biotic homogenization. The present study tests this hypothesis by examining whether spatial and temporal variations in contemporary composition and dynamics of bird communities are related to past changes in HNV farmland within a 30-year period. Analyses of three farmland types were made in areas of (1) highly intensified agriculture, (2) relatively recent agriculture intensification and (3) low-intensity agriculture identified as HNV farmlands. French farmland in its whole is currently subjected to biotic homogenization processes. However, no homogenization was observed in HNV farmland, potentially indicating that those areas were not affected – or at least not at the same pace as elsewhere – by biotic homogenization. Farmland species population trends remain high in recent non-HNV farmlands, indicating that some non-HNV areas may still contribute in refraining farmland biodiversity decline. Future conservation focus should be given in priority in HNV farmland, but also in areas of recent agriculture intensification, to buffer further negative effects on population and community dynamics.

► Biotic homogenization is observed in French agroecosystems.
► In High Nature Value farmland this phenomenon is potentially refrained.
► Farmland Bird Indicator trends remain high in recent non High Nature Value farmlands.