Impact of agricultural landscape structure on the patterns of bird species diversity at a regional scale

The loss of bird species diversity is a crucial problem in the European agricultural landscape. Change in the area coverage of major land cover types has been mentioned as one of the main factors responsible for bird biodiversity impoverishment. In this study, we focused on the impact of landscape matrix characteristics on bird species richness and on Faith's phylogenetic diversity index on a spatial scale of 1000-m radius around the measured occurrence points. We investigated how land cover composition affects bird diversity on the landscape scale using nationwide citizen science data. In total, 168,739 records of bird occurrence in the South Moravian Region of the Czech Republic during growing season from 2009 to 2019 were evaluated. We found that the presence of water bodies and wetlands significantly corresponded to the areas of highest bird species richness. We also revealed that the presence of forests (~60% of the forest in the Czech Republic is occupied by commercial forests), urban areas and arable land were negatively associated with bird species richness and phylogenetic diversity. Forests (both coniferous and deciduous) and urban habitats were found to have a tendency to host a clustered phylogenetic community structure in comparison with wetland and arable land. A strong negative association between forest proportion and bird diversity led us to conclude that the expansion of the forest (with simple species composition, horizontal and vertical structure) could be one of the critical drivers of the decline of bird species diversity in the European agricultural landscape. On the other hand, our results also pointed out that small woody features (i.e., woodlots) and scattered woodland shrub vegetation were one of the main landscape characteristics supporting a bird diversity in rural landscape. This is in concordance with other studies which mention these landscape structures as important elements for nesting and foraging of farmland birds. We thus recommend to maintain and restore scattered trees or woodlots with complex structure in agricultural landscape.