Effects of agricultural intensity and landscape pattern on terrestrial birds in China's agroecosystem differ between temperature zones

Agriculture expansion and development have caused a biodiversity decline including birds. China has extensive agricultural lands and high farmland biodiversity; however, how agricultural landscapes and practices affect bird diversity in China is unclear. We estimated the spatial patterns of bird species richness (SR), functional diversity (FD), and the standardized effect size of the mean functional distance (SES.MFD) in China's agricultural region using the distribution data of 652 terrestrial bird species predicted by improved MaxEnt-modeling approaches, and assessed their relationships with landscape pattern and agricultural intensity in different temperature zones. Both bird SR and FD generally increased from northwest to South China, while the SES.MFD trend was the opposite. Bird SR and FD were positively related to woodland proportion, wetland proportion and landscape diversity. Yet impacts of agricultural intensity varied between temperature zones, showing negative effects on bird SR and FD in tropical, subtropical and warm temperate zones, but positive in middle temperature and plateau climate zones. With the increase in agricultural intensity, the community structure of birds clustered in tropical, subtropical and warm temperate zones, but dispersed in middle temperature zone. These results affirm natural landscape and landscape heterogeneity in maintaining terrestrial bird diversity in China's agroecosystems. Further, region-specific farmland biodiversity strategies are recommended, highlighting the management of cropland and agrochemical use in South China and taking advantage of the cropland value for bird conservation in relatively cold regions.