丛枝菌根真菌和外生菌根真菌对凋落物分解的影响机制

丛枝菌根（AM）真菌和外生菌根（EM）真菌与约80%的维管植物可形成共生体，其共生体除了促进植物生长发育外，还具有调节凋落物和土壤有机质分解的重要生态功能。在AM和EM真菌主导的生态系统中，凋落物分解速率在不同的基质类型（AM树种凋落物、EM树种凋落物）、不同的分解阶段（早期阶段、后期阶段）和不同的环境条件（水分、温度等）下均存在显著差异。虽然部分菌根真菌缺乏腐生生物的直接作用于凋落物的能力，但它们通过其他方式影响分解。普遍认为，AM和EM真菌与腐生微生物的相互作用是影响分解速率的主要原因，二者互作机制主要表现为激发效应（向腐生微生物提供能量）和养分竞争效应（与腐生微生物竞争养分）。文中阐述AM和EM真菌对凋落物分解的影响及相关因素，剖析AM和EM真菌与腐生微生物分解凋落物的作用机制，旨在为全面分析AM和EM真菌在森林生态系统中的生态学功能提供参考。

Acting Mechanisms of AMF and EMF Regulating Litter Decomposition

The arbuscular mycorrhizal (AM) fungi and ectomycorrhizal (EM) fungi can develop mutualistic symbiosis with about 80% vascular plants across the world. In addition to promoting plant growth, the mutualistic symbiosis plays an important role in regulating the decomposition of litter and soil organic matters. In the ecosystem mediated by AM fungi and EM fungi, the decomposition rate of litters varies in different substrate types (AM tree species litter, EM tree species litter), at different decomposition stages (early stage, late stage) and in different environmental conditions (moisture, temperature, etc.). Although some mycorrhizal fungi lack the ability of saprotrophs to decompose litter directly, they use other strategies to affect decomposition. It is commonly held that the interaction of AM fungi and EM fungi with saprotrophic microbes is the main actor affecting decomposition rate, and priming effect (providing labile C to saprotrophic microbes) and nutrient competition effect (competition with saprotrophic microbes) are the main mechanisms under the interaction. We review the effects of AM fungi and EM fungi on litter decomposition and its related factors, and analyze the acting mechanism of interaction between AM fungi and EM fungi and saprotrophs in decomposing litter. The study is aimed to provide reference for comprehensively understanding the ecological functions of AM fungi and EM fungi in forest ecosystems.