Dominated Taxonomic and Phylogenetic Turnover but Functional Nestedness of Wetland Bird Beta Diversity in North China

The decomposition of taxonomic, phylogenetic, and functional beta diversity into their turnover and nestedness components could provide novel insights into biodiversity conservation, e.g., provide implications for the Single Large Or Several Small reserves debate (SLOSS debate). Due to dramatic climate change and massive anthropogenic activities in recent decades in North China, the wetlands and the associated biodiversity in this region have declined significantly. This study applied the taxonomic, phylogenetic, and functional beta diversity decomposition for the first time in wetland bird communities in North China, aiming to propose scientific and comprehensive suggestions for bird diversity conservation in this region. A paired t -test was used to compare the differences between taxonomic, phylogenetic, and functional turnover, and their nestedness components. In addition, a spearman correlation analysis was used to assess the associations between each explanatory variable (differences in mean annual temperature and mean annual precipitation, as well as spatial distances) and each beta diversity index. A total of 546 bird species were found in 38 wetlands in North China, with three critically endangered species, 19 endangered species, 22 vulnerable species, and 61 near threatened species. The number of threatened species (critically endangered, endangered, and vulnerable) found in these lakes was about 30% of all threatened species in China. The results showed that taxonomic and phylogenetic beta diversity among wetland bird communities in North China was mainly dominated by turnover, while functional beta diversity was mainly dominated by nestedness. Importantly, the phylogenetic and functional results showed similar patterns even after controlling for the effects of taxonomic beta diversity. In addition, the taxonomic and phylogenetic turnover was more associated with both climate variables and spatial distances than other components. The contrasting patterns among the taxonomic, phylogenetic, and functional decompositions of wetland bird communities in North China indicate that distinctive conservation strategies should be considered for different biodiversity dimensions. Specifically, the conservation of taxonomic and phylogenetic bird diversity in this region should focus on multiple wetlands, while the conservation of bird functional diversity should focus on a single wetland with high functional diversity.