There is increasing concern regarding how plant diversity affects litter decomposition. However, few experiments have simultaneously investigated the independent effects of litter species composition and the richness of above-ground tree communities on litter decomposition. To elucidate the two facets of diversity effects on leaf litter decomposition, a field experiment with litterbags containing monospecific or mixed litter of Schima superba, Cyclobalanopsis glauca, and Castanopsis eyrie was conducted for 30 consecutive months in a subtropical forest. In addition, the fungal community composition of the decomposing litter was assessed in the later decomposition stage. Our results revealed that leaf litter species composition but not litter species richness per se affected decomposition rates, in which the decomposition rates were faster in the presence of S. superba litter but slower in the presence of C. eyrei litter. Soil properties showed stronger impacts on litter mass loss in the earlier stages, while the litter species composition became more important in the later stage. Moreover, above-ground tree species richness had a significant effect on leaf litter decomposition. As expected, the effects of above-ground tree species richness and litter species composition became much stronger with time, probably owing to the indirect effects of concomitant changes in the composition of the litter fungal community, which in turn depended on the changes of microenvironment or on accumulated recalcitrant substances in the late stage of decomposition. Overall, our findings demonstrate that not only litter species composition but also above-ground tree species communities play critical roles in regulating litter decomposition, particularly in the late stage. An investigation into the interactions between plant and decomposer communities is required to gain a full understanding of the mechanisms underlying litter mixture decomposition.

人们越来越关注植物多样性如何影响凋落物分解。然而，很少有实验同时研究凋落物物种组成和地上树木群落丰富度对凋落物分解的独立影响。为了阐明在凋落叶分解的分集效应的两个小平面，与含有单特异性的或混合凋落垫料的场实验木荷，青冈和栲艾里在一个亚热带森林连续30个月进行。此外，在分解后期评估了分解凋落物的真菌群落组成。我们的研究结果表明，凋落物物种组成而不是凋落物物种丰富度本身影响分解速度，其中在S. superba垃圾存在下分解速度更快，而在C. eyrei存在下分解速度更慢垃圾。前期土壤特性对凋落物质量损失的影响较大，而后期凋落物种类组成变得更加重要。此外，地上树种丰富度对凋落物分解有显着影响。正如预期的那样，地上树种丰富度和凋落物物种组成的影响随着时间的推移变得更加强烈，这可能是由于凋落物真菌群落组成的伴随变化的间接影响，而这反过来又取决于微环境的变化或分解后期积累的顽固物质。总体而言，我们的研究结果表明，不仅凋落物物种组成而且地上树种群落在调节凋落物分解方面发挥着关键作用，尤其是在后期。