Leaf litter decomposition is a fundamental process involved in soil carbon and nitrogen dynamics. Observational and experimental evidence suggests that leaf litter from arbuscular mycorrhizal (AM) tree species has a faster decomposition rate than leaf litter from ectomycorrhizal (ECM) tree species. This could be due to the diversity and activity of decomposer microorganisms, but remains to be confirmed in subtropical forests. In this study, we compared the effects of fungi and bacteria on decomposition rates of litter from AM and ECM subtropical trees. In the field, we conducted a fungal hyphal exclusion experiment beneath AM and ECM trees. We also used fungicides and bactericides to distinguish the contribution of bacteria and fungi to litter decomposition in a shade-house experiment. Fungi were responsible more leaf litter decay in soil around AM trees than in soil around ECM trees. When fungi were excluded, AM and ECM litters with similar chemical properties decomposed at the same rate, but the AM litters decayed more quickly when saprotrophic fungi were present. Soil around AM trees had more abundance of saprotrophic fungi and greater N-acetylglucosaminidase and acid phosphatase activities than soil around ECM trees. We conclude that the higher leaf litter decomposition rates under AM trees were due to the saprotrophic fungi in the soil microbial community.

凋落物分解是涉及土壤碳氮动态的基本过程。观测和实验证据表明，丛枝菌根（AM）树种的凋落物的分解速率比外生菌根（ECM）树种的凋落物的分解速率快。这可能是由于分解微生物的多样性和活性所致，但仍有待在亚热带森林中得到证实。在这项研究中，我们比较了真菌和细菌对AM和ECM亚热带树木凋落物分解速率的影响。在野外，我们在AM和ECM树下进行了真菌菌丝排斥实验。我们还使用杀真菌剂和杀菌剂来区分细菌和真菌在遮阴棚实验中对垃圾分解的贡献。与AM树木周围的土壤相比，真菌对AM树木周围的土壤凋落物的破坏作用更大。当排除真菌时，具有相似化学性质的AM和ECM凋落物以相同的速率分解，但是当存在腐生真菌时，AM凋落物的分解速度更快。与ECM树木周围的土壤相比，AM树木周围的土壤具有更多的腐生真菌，并且具有更大的N-乙酰氨基葡萄糖苷酶和酸性磷酸酶活性。我们得出结论，AM树下较高的凋落物分解率是由于土壤微生物群落中的腐生真菌引起的。与ECM树木周围的土壤相比，AM树木周围的土壤具有更多的腐生真菌，并且具有更大的N-乙酰氨基葡萄糖苷酶和酸性磷酸酶活性。我们得出结论，AM树下较高的凋落物分解率是由于土壤微生物群落中的腐生真菌引起的。与ECM树木周围的土壤相比，AM树木周围的土壤具有更多的腐生真菌，并且具有更多的N-乙酰氨基葡萄糖苷酶和酸性磷酸酶活性。我们得出结论，AM树下较高的凋落物分解率是由于土壤微生物群落中的腐生真菌引起的。