Precipitation determines the magnitude and direction of interannual responses of soil respiration to experimental warming

Background and aims Soil respiration (R-s) is expected to positively feedback to climate warming. The strength of this feedback is uncertain as numerous environmental factors, such as precipitation and soil moisture, can moderate the warming response of R-s. Methods We combined seven-year R-s measurements in a warming experiment in the Tibetan alpine grassland with a meta-analysis on grassland warming experiments globally to investigate how precipitation and soil moisture influences the warming response of R-s. We further analyzed the warming responses of heterotrophic (R-h) and autotrophic (R-a) components of R-s. Results Warming enhanced growing-season R-s in the wet years but decreased it in the dry years in the field experiment at the Tibetan grassland. Precipitation modulated the warming responses of growing-season R-s via R-h, but not R-a. Consistent with the field experiment, a positive relationship between precipitation and the warming response of growing-season R-s was also observed in the global-scale meta-analysis on grassland warming experiments. Conclusions Precipitation influences the warming effects on R-s and could result in variation in warming response of R-s across years and experimental systems. Empirical functions provided by this study could be used to reduce the uncertainty in predicting R-s in a warmer future.

Automated summary

The study found that precipitation influences the warming effects on soil respiration, leading to variation in warming response of R-s across different years and experimental systems. Additionally, empirical functions provided by the study can help reduce uncertainty in predicting soil respiration in a warmer future.