Seasonal effects of urban park landscape structure on taxonomic, functional, and phylogenetic diversity of birds

Urban parks serve as important biodiversity refuges in highly urbanized landscapes, yet the landscape mechanisms shaping seasonal dynamics of multidimensional avian diversity remain poorly understood. Using citizen-science bird observation data collected from 2021 to 2024, we investigated variation between the breeding and wintering seasons in taxonomic, functional, and phylogenetic diversity of bird communities across 30 urban parks in Beijing, China. Species richness did not differ significantly between the breeding and wintering seasons, whereas phylogenetic diversity and functional diversity were significantly lower in the wintering season, with community structure exhibiting clear phylogenetic and functional clustering. Park area and landscape heterogeneity (SHDI) positively influenced multidimensional avian diversity in both seasons, whereas edge density (ED) positively affected community structure and assembly patterns only during the wintering season. The proportion of impervious surfaces negatively influenced phylogenetic structure across both seasons, but exerted contrasting effects on functional structure, promoting functional structure during the breeding season while inhibiting it during the wintering season. Overall, this study highlights the importance of a multidimensional and seasonal perspective in urban biodiversity research, identifies key landscape features that sustain avian diversity in temperate urban parks across the breeding and wintering seasons, and provides a scientific basis for urban green space planning and management.