Additive effects of multiple global change drivers on terrestrial nitrogen cycling worldwide

We found that the interactions of multiple GCFs were commonly additive (66.2%–83.3%), but both synergistic (10.5%–15.1%) and antagonistic (2.8%–18.9%) effects were also observed.Using Web of Science, Google Scholar and the China National Knowledge Infrastructure, we collected a total of 1722 observations from 108 peer-reviewed articles that reported changes in N cycling under experimental manipulations of warming (W) and other global change drivers, including increased precipitation (IP), decreased precipitation (DP), nitrogen addition (N), and elevated CO2 concentration (eCO2).We used a widely accepted bias-corrected method to quantify individual effects and the combined effects of global change drivers on plant sequential phenophases (effect size: Hedges' g). The interactive effect and main effect for judging the interaction types of combined effect were calculated as Hedges' d.