氮磷添加对土壤真菌在木质残体中定殖及群落特征的影响

Effects of Nitrogen and Phosphorus Addition on Colonization and Community Characteristics of Soil Fungi in Woody Debris

土壤真菌对木质残体的定殖会对木质残体真菌群落及其分解产生重要影响。氮、磷是真菌生命活动所需的重要养分,但目前仍不清楚外源氮、磷的输入如何影响土壤真菌对木质残体的定殖。基于亚热带森林生态系统中8个典型树种为期3年的木质残体分解实验,本研究揭示了氮磷添加对土壤到木质残体的真菌定殖的影响。结果表明,木质残体中有34.5%~40.9%的真菌物种来自土壤。磷添加与氮磷添加均会降低定殖真菌在木质残体真菌物种中的比例,磷添加还会显著降低定殖真菌的丰富度。定殖真菌在纲水平上主要有伞菌纲、粪壳菌纲、锤舌菌纲、座囊菌纲以及散囊菌纲。其中,伞菌纲是主要的定殖真菌类群,其相对丰度在磷添加下增加而在氮添加下减少,变化范围为62.39%~76.35%。此外,定殖真菌以腐生菌为主,其次是外生菌根真菌等其他功能类群。磷添加抑制了腐生菌以及外生菌根真菌从土壤到木质残体的定殖,氮添加则促进腐生菌在木质残体中的定殖。最后,分析木质残体中定殖真菌类群的生态策略发现,木质残体中的定殖真菌类群以寡营养类群为主。相较于氮添加,磷添加显著增加了木质残体中寡营养类群的比例。研究强调了亚热带森林生态系统中土壤对木质残体真菌群落组成的重要影响,同时突出了氮磷添加对从土壤到木质残体的真菌定殖过程的重要调控作用,这对于理解森林生态系统中木质残体分解的微生物机制具有重要意义。

The colonization of woody debris by soil fungi significantly influences its decomposition and the structure of the fungal community.Although nitrogen and phosphorus are essential for fungal activity,the effects of external nitrogen and phosphorus inputs on the fungal colonization of woody debris remain not fully understood.Through a three-year study on the decomposition of woody debris from eight typical tree species in a subtropical forest ecosystem.This research reveals the impact of nitrogen and phosphorus supplementation on fungal transfer from adjacent soil to woody debris.This study found that between 34.5%and 40.9%of fungal species in woody debris originated from soil.The addition of phosphorus,as well as combined nitrogen and phosphorus,decreased the proportion of colonized fungi in the fungal species of the woody debris.Additionally,phosphorus addition significantly reduced their richness.The main classes of colonized fungi included Sordariomycetes,Leotiomycetes,Dothideomycetes,and Eurotiomycetes.Among these,Sordariomycetes was the primary colonized group,with its relative abundance increasing with phosphorus addition and decreasing with nitrogen addition,ranging from 62.39%to 76.35%.Furthermore,these colonized fungi predominantly belonged to saprotrophic,followed by ectomycorrhizal and other functional groups.Phosphorus addition inhibited,while nitrogen addition promoted the colonization of both saprotrophic and ectomycorrhizal fungi from soil to woody debris.Last but not the least,analysis of the ecological strategies of the colonized fungal groups in woody debris indicates a predominance of oligotrophic groups,especially under phosphorus addition.This study highlights the crucial role of soil fungi in shaping the fungal community composition of woody debris in subtropical forests and emphasizes the significant regulatory effect of nitrogen and phosphorus additions on colonization,offering important insights into the microbial mechanisms of woody debris decomposition in forest ecosystems.