Meta-analysis shows experimental warming facilitated global litter decomposition and nitrogen release

Abstract

Aims

Plant litter decomposition (LD) is one of the largest global carbon (C) fluxes and is particularly vulnerable to global warming. However, it is not clear how environmental and experimental factors interact with experimental warming to affect LD, C, and nutrient release.

Methods

Therefore, a global meta-analysis of 713 pairwise observations from 71 published papers was conducted to evaluate the effects that field warming had on LD and associated nutrient releases across terrestrial ecosystems.

Results

Experimental warming significantly stimulated global LD and nitrogen (N) release by 1.80% and 2.14%, respectively, but did not significantly affect C and phosphorus (P) release. There were also significant warming intensity and litter quality effects. Litter decomposition increased at low warming intensities (≤ 1 °C) and when low-quality litter (high lignin levels and/or high C:N and lignin:N ratios) was low. The warming effects on LD changed from negative to positive as the humidity index increased. In addition, the results showed that experimental factors and characteristics considerably influenced the LD responses to experimental warming. Moreover, the stimulatory effect of experimental warming on LD disappeared during longer-term decomposition (> 1 year), which suggested that warming only had a short-term promotional effect on LD and N release.

Conclusions

The results showed that LD and nutrients release under experimental warming are relatively sensitive to experimental and environmental factors, including warming intensities and duration, climate, and litter quality, and that these factors should be considered in the biogeochemical cycles model to improve predictions about the global warming effects on LD and nutrient cycling.