Importance of surrounding landscape features in explaining wintering waterbird diversity and community assembly in Jiangsu's inland lake wetlands

Abstract

As one of the important wintering areas along the East Asian–Australasian Flyway, wetlands in the Yangtze River floodplain face threats from land-use changes, yet its effects on wintering waterbirds at the landscape level remain understudied, impeding conservation practice. Here, using survey data collected across 14 inland lakes in Jiangsu Province in 2022, we calculated wintering waterbirds diversity (taxonomic, functional, phylogenetic) and assembly patterns (MPD/MNTD of functional and phylogenetic). Then, we interpreted satellite imagery of lake areas and buffer zones (5 km), and partitioned them into three land-use and landscape index categories (anthropogenic, ecological, and lake landscape). Finally, we employed multiple linear regression and hierarchical partitioning to explain the influence of landscape scales on wintering waterbird communities. Our results showed that the diversity and assembly of regional wintering waterbird communities tended to be consistent across taxonomic, functional, and phylogenetic dimensions. The standardized diversity indices indicated that functional assembly of communities tends to be clustered at both local and regional scale. In contrast, the phylogenetic structure showed a predominantly overdispersed pattern in most lakes at the local scale, while neutral processes dominated at the regional scale. Modeling showed that selected variables explained waterbird diversity and assembly well. Lake fragmentation increased species evenness but reduced other diversity indices, while landscape evenness was negatively associated with functional and phylogenetic assembly. Among anthropogenic factors, aquaculture ponds and impervious surfaces reduced all diversity dimensions, whereas cropland connectivity enhanced phylogenetic diversity. These factors had consistent effects on community assembly. For ecological variables, grassland area enhanced functional and phylogenetic diversity but led to more clustered functional assembly. Overall, maintaining the integrity and connectivity of lakes and their surrounding landscapes is essential for sustaining waterbird diversity and guiding wetland restoration.