Avian phylogenetic and functional diversity and their influencing factors in urban parks of Nanjing, China

The acceleration of global urbanization has caused habitat loss, fragmentation, and decrease of habitat quality, often leading to a decline in biodiversity. However, most previous urbanization studies focused on taxonomic diversity, with relatively less research on functional and phylogenetic diversity. In this study, we examined the phylogenetic and functional diversity and underlying influencing factors of bird communities in 37 urban parks in Nanjing, China. We conducted a systematic survey of bird communities in Nanjing urban parks and selected six park characteristics that are generally considered to affect bird diversity. Model selection based on corrected Akaike Information Criterion (AICc) and model averaging showed that park area, habitat diversity and building index (a proxy for the degree of urbanization) were significant factors affecting avian phylogenetic and functional diversity in Nanjing urban parks. Specifically, habitat diversity and park area were positively correlated with bird diversity, while the building index was negatively correlated with bird diversity. Moreover, the phylogenetic and functional structures of urban bird communities exhibited a clustered pattern, indicating that environmental filtering might play a role in shaping community composition. In addition, building index had certain impact on the construction of bird phylogenetic communities in urban parks. Our results suggest that expanding park areas, increasing habitat diversity and reducing building indexes may be effective measures to increase the avian phylogenetic and functional diversity in our system.