Differential responses of litter decomposition to warming, elevated CO2, and changed precipitation regime

Background and aims Litter decomposition is a fundamental process of biogeochemical cycles and particularly sensitive to global change. However, the overall effects of warming, elevated carbon dioxide and changed precipitation regime on litter decomposition are not well studied. Methods To assess the effects of these three common global change factors on litter decomposition, we performed a meta-analysis using 366 pairwise observations from 103 published articles. We quantified the responses of litter decomposition rate to the effects of warming, elevated CO2, and changed precipitation regime (increased and decreased). Results At the global scale, warming and precipitation addition significantly stimulated litter decomposition rate by an average of 4.20% and 11.72%, respectively. In contrast, elevated CO(2)and precipitation removal showed significant negative effects on litter decomposition rate (-2.99% and - 12.60%). In addition, study type, plant functional traits, and climate were consistent moderators. These results indicate that warming, elevated CO2, and changed precipitation regime have significantly affected litter decomposition, but the direction and magnitude of the effects of different factors varied, and were also differently mediated by moderator variables. Conclusions Global cycles of carbon and nutrients via the litter decomposition process can be substantially affected by global change. However, the combined effects of these global change factors on litter decomposition and the different effects between the arid and humid areas cannot be addressed due to the lack of data, indicating the need of more focus on multi-factor manipulative experiments in a wider range of study sites.