Data from: Decade-long bird trends in China: Stable species richness but increasing biotic homogenization

While China harbors rich biodiversity, it is facing concurrent challenges from rapid socio-economic growth and severe biodiversity loss. Additionally, critical gaps in knowledge about the country’s biodiversity trends have persisted for a long time because of a lack of a national-scale biodiversity monitoring program. Using a decade (2011-2020) of avian monitoring data from 142 sites and 864 species under the China Biodiversity Observation Network, we evaluated temporal trends in alpha and beta diversity, examining both the taxonomic and functional facets of biodiversity, and assessed their drivers. We found that species richness remained stable over 10 years, with no directional trend at 84.5% of sites and a small mean effect size (Zr = 0.102, 95% CI = [-0.012; 0.216]). In contrast, functional richness increased significantly (Zr = 0.122, 95% CI = [0.016; 0.227]). Taxonomic multiple-site beta diversity decreased over time (P