Extended Data Fig. 2: Effects of four years of extreme drought on absolute value of ecosystem productivity and species richness, and the relationship between species richness and the response of productivity to extreme drought.

a, the response of aboveground net primary productivity (ANPP). b, the response of plant species richness. c, the relationship between total species richness and the response ratio of ANPP. d, the relationship between subordinate species richness and the response ratio of ANPP. Total and subordinate species richness were the absolute values observed in ambient plots. Values are mean ± s.e.m. of the absolute values of ANPP and species richness in six Eurasian grasslands (n = 36) and six North American grasslands (n = 60). Statistical significance of the values between treatments is depicted as *, p < 0.05, which was assessed by Tukey’s HSD tests (two-sided). Lines are mixed-effects model fits for each trend. The purple, yellow and grey lines indicate the trends averaged across all Eurasian grassland sites (n = 24), averaged across all North American grassland sites (n = 24) and the trends for each site (n = 4), respectively. Solid lines indicate significant associations, while dashed lines indicate non-significant associations (see Supplementary Table 3 for detailed model specification and summary statistics).