Grassland winners and arable land losers: The effects of post-totalitarian land use changes on long-term population trends of farmland birds

Biodiversity loss is an ongoing problem of European farmland and recent studies show that causes of this loss may vary among regions. At the same time, Eastern European post-totalitarian countries hold key part of farmland biodiversity within Europe but drivers of its changes remain poorly known due to lack of studies based on long-term data from this region. To fill this gap in our knowledge, we investigate how the post-totalitarian transformation of agricultural management, resulting in widespread land abandonment, affected land cover composition and, in turn, long-term changes of farmland bird populations in an Eastern European former communist country, the Czech Republic. Besides intensification in the most productive areas, we hypothesized that two scenarios might occur: (i) loss of farmland area resulting from its transformation to forests, successional habitats or built areas, (ii) conversion of highly energy-demanding arable land to extensively managed grassland. CORINE land cover data supported the second scenario with a massive gain of grassland area at the expense of arable land, while changes in areas of forest and successional habitats were only slight. This land cover change corresponded well with population increase of grassland birds and population decline of arable land birds, whereas mean population change of species associated with shrub and trees habitat was close to zero. These patterns are quite unique within biodiversity studies reporting declines of grassland bird species in North America and Western Europe, or shrub encroachment accompanied with increasing abundance of shrub-dwelling species in Southern Europe and South Africa. We suggest that the results found in the Czech Republic may also hold in other post-totalitarian Eastern European countries. Based on our findings, we recommend that the agri-environmental schemes applied in the Czech Republic, which focused mainly on grasslands and were only minimally represented on arable land, should now target on halting continuous decline of biodiversity on arable land.