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Background and aims In upland ecosystems, climate and initial litter quality are the two major factors influencing decomposition rates regionally and globally. Litters are exposed to a different decomposition environment in wetlands than in upland ecosystems, but the driving factors of litter decomposition in wetlands at a large scale are still unclear.

Methods We established a comprehensive database of litter decomposition in China, including 249 datasets and 27 pairs of sites, to examine the controlling factors of decomposition in both wetland and upland ecosystems at the regional scale.

Results Both ecosystems showed similar climatic conditions, but the average litter decomposition potential was higher in wetlands than in upland ecosystems, as indicated by a higher initial K content and lower initial carbon content. The average decomposition rate in wetlands was almost 3 times higher than that in upland ecosystems. In both ecosystems, the decomposition rate increased with the mean annual temperature, mean annual precipitation, and initial N content. However, linear regressions of these variables with the decomposition rate indicated steeper slopes in wetlands than in upland ecosystems.

Conclusions The litter decomposition rate responded to climate and initial N content in both ecosystem types, but these responses were more rapid in wetlands than upland ecosystems. Wetland ecosystems should be given more attention when studying the responses of litter dynamics to future climate changes.