Aim Leaf litter decomposition in freshwater ecosystems is a vital process linking ecosystem nutrient cycling, energy transfer, and trophic interactions. In comparison to terrestrial ecosystems, in which researchers find that litter traits predominantly regulate its decomposition worldwide, the dominant factors controlling litter decomposition in aquatic ecosystems are still debated with global patterns not well documented. Here, we aimed to explore general patterns and key drivers (e.g. litter traits, climate, and water characteristics) of leaf litter decomposition in streams worldwide. Location Global Time period 1977-2018 Leaf litter Methods We synthesized 1707 records of litter decomposition in streams from 275 studies. We explored variations in decomposition rates among climate zones, tree functional types, and between mesh size groups. Regressions were performed to identify the factors that play dominant roles in litter decomposition globally. Results Litter decomposition rates did not differ among tropical, temperate, and cold climate zones. Decomposition rates of litter from evergreen conifer trees (EC) were much lower than those of deciduous and evergreen broad-leaf trees (DB and EB), attributed to the low quality of litter from EC. No significant differences were found between decomposition rates of DB and EB. Additionally, litter decomposition rates were much higher in coarse- than in fine-mesh bags, which control the entrance of decomposers of different body sizes. Multiple regressions showed that litter traits (including lignin, C:N ratio) and altitude were the most important factors in regulating leaf litter decomposition. Main conclusions Litter traits predominantly control leaf litter decomposition in streams worldwide. While further analyses are necessary to explore whether commonalities of litter traits' predominant role in decomposition exist in both aquatic and terrestrial ecosystems, our findings could contribute to using trait-based approaches in modeling the decomposition of litter in streams globally and exploring mechanisms of land-water-atmosphere carbon fluxes.
|Date made available||2019|