Asymmetric responses of litter decomposition to altered precipitation: Double evidence from field experiments and global synthesis

<p>Altered precipitation regimes as a result of global climate change have significant implications for ecosystem processes, such as the decomposition of litter, a vital process in carbon (C) and nutrient cycling in terrestrial ecosystems. However, the effects of altered precipitation regimes on litter decomposition across humid and arid biomes remain unresolved. To address this knowledge gap, we conducted a comparative analysis using data from a geographically replicated precipitation‒manipulation field experiment that studied litter decomposition and a global meta-analysis of 778 paired observations from 207 peer-reviewed articles. Our findings indicated that the litter decomposition constant (<i>k</i>) was 7.7–31.3% greater under increased precipitation and 10.0–41.0% lower under decreased precipitation than under the control treatments. Litter decomposition, soil moisture, microbial biomass, and enzymatic activity had stronger responses to increased precipitation in the arid region and to decreased precipitation in the humid region, which was consistent with the double asymmetric model. A global meta-analysis also confirmed the asymmetrical effects of altered precipitation regimes on litter decomposition between humid and arid regions. Our results highlight the potential asymmetry in the effects of altered precipitation regimes on C and nutrient cycling between humid and arid terrestrial ecosystems.</p>