3.3 Species richness of communities and functional groups and their relationship with climate factors
Community species richness ranged from 18 to 44 (mean 34), and declined through time (Fig. 4a; P = 0.001; R2 = 0.34). The average rate of loss of species richness was 4.5 species m-2decade-1 during the period of 1981–2011. Similar to community species richness, species richness of functional group PF decreased during the observation period (Fig. 4d; P = 0.003; R2 = 0.29). In contrast, we found no trend of species richness of functional groups PR, PB, SS, and AB through time (Fig. 4b-c, e-f). The average loss rate of species richness of functional group PF was 3.7 species m-2decade-1, community species richness was largely related to the species richness of functional group PF (Fig. S3).