Fig. 3
a Average concentrations of microbial biomass C, microbial necromass C, and soil organic C at control (red) and N addition (blue) plots across the studied sites. The box plots show the median and 25th and 75th percentiles. The values show percent changes in microbial biomass C, microbial necromass C, and soil organic C under N addition. All these variables were collected at the control and N addition plots at the 11 sites at which microbial necromass C data were obtained. Microbial biomass C values are presented on the basis of chloroform fumigation extraction analysis. b, c The effect sizes of N addition on microbial necromass C plotted against the effect sizes on microbial biomass C and soil organic C, respectively. d Proportions of microbial necromass C in soil organic C versus those of microbial biomass C in soil organic C. e, f The concentrations of microbial necromass C versus those of microbial biomass C and soil organic C, respectively. All data shown in panels d–f were collected at control plots, and error bars represent the standard errors. The dotted lines show the 95% confidence intervals, and the adjusted R2 and P values are shown in all panels except panel a