Fig. 2: Schematic representation of the data analysis workflow for this study.
From: A general framework for nitrogen deposition effects on soil respiration in global forests
a Global atmospheric N deposition data were from Ackerman et al.9. b Experimental N addition forests with observations of soil respiration (CO2_exp dataset). c Non-experimental forests with observations of soil respiration (CO2_obs dataset)41. Basemap was from Resource and Environmental Science Data Platform (www.resdc.cn). d Global forest N saturation status data were from Cen et al.13. e Hypothesized response of the increased soil respiration (SR) to N inputs. f Hypothesized response of the decreased SR to N inputs. SRCL: soil respiration rate measured in the control plot receiving natural nitrogen deposition (Ndep). SR+N: soil respiration rate measured in the experimental plot receiving an additional N input (Nadd). ∆SRN-inc: increased SR by N input. ∆SRN-dec: decreased SR by N input. fpos: positive response factor of increased SR to N input. fneg: negative response factor of decreased SR to N input (see Supplementary Text S1 for the biochemical and ecological theories underlying the response factors). Pdec: Probability of SR being decreased by N input, estimated as the proportion of experimental N addition forests where a N input rate caused a decreased in soil respiration.
