青藏高原高寒草甸土壤真菌多样性与植物群落功能性状和土壤理化特性的关系

Relationships between soil fungal diversity, plant community functional traits, and soil attributes in Tibetan alpine meadows

为探究高寒草甸土壤真菌多样性与植物群落功能性状(community-weighted mean,CWM;functional diversity,FD)及土壤理化特性的关系,选取3个试验点,每个试验点选择4种生境(沟底平地、阴坡、阳坡和山顶),采用高通量测序技术分析各生境土壤真菌多样性特点;利用广义线性混合模型,比较土壤真菌优势类群(门和属水平)及土壤理化特性在不同试验点和生境之间的差异;采用多元分析和偏回归检验土壤真菌多样性与群落水平功能性状(CWM)和性状多样性(FD)及土壤理化特性的关系.结果表明:(1)高寒草甸土壤真菌在门水平上的优势类群为接合菌门、子囊菌门、担子菌门和球囊菌门,在属水平上的优势类群为被孢霉属、隐球菌属、丝盖伞属、蜡壳菌属和蜡伞属.接合菌门、球囊菌门及被孢霉属在不同生境的分布存在显著差异,在山顶接合菌门和被孢霉属的相对丰度显著高于其他3种生境(沟底平地、阴坡和阳坡),在沟底球囊菌门的相对丰度显著高于其他3种生境(阴坡、阳坡和山顶).(2)土壤理化特性能够解释土壤真菌丰富度变化的21%.土壤真菌丰富度随土壤pH、全氮和速效氮的增加而增加,随土壤有机碳、有机质和碳氮比的增加而降低.(3)植物群落水平功能性状能够解释20%的土壤真菌丰富度变化.土壤真菌丰富度与植物群落水平的植株高度呈显著负相关.(4)植物群落性状多样性能够解释土壤真菌丰富度变化的33%.土壤真菌丰富度随植物群落叶片氮和磷含量多样性的增加而增加,随植株高度和叶片干物质含量的增加而减小;土壤真菌Shannon指数与土壤理化特性及植物群落功能性状均无显著相关性.因此,植物群落功能性状和土壤理化特性可共同解释高寒草甸土壤真菌丰富度的变化,植物群落性状多样性与土壤真菌群落协同变化,可促进高寒草甸生态系统稳定性维持.

In this study, we investigate the relationships between soil fungal diversity, plant community functional traits(community-weighted mean, CWM, and functional diversity, FD), and soil attributes under various habitats(valley, north and south slopes, and top hill) at each of three test sites. High-throughput sequencing technology was applied to analyze soil fungal diversity. Five key functional traits were investigated for four typical habitats of three test sites to quantify CWM and FD. A generalized linear mixed model was used to examine the relationship between soil fungi community and soil attributes, CWM and FD, in four typical habitats of the three test sites. Generalized canonical discriminant analysis and partial regression were conducted to analyze the correlation among soil fungal diversity and soil attributes.(1) The dominant fungal phyla in alpine meadows were Zygomycota, Ascomyceta, Basidiomycota, and Glomeromycota, and the dominant genera were Mortierella, Cryptococcus, Inocybe, Sebacina, and Hygrocybe. There were significant difference among the four habitats for Zygomycota, Glomeromycota, and Mortierella. The relative abundance of Zygomycota and Mortierella in top hill soil was significantly higher than that in the other three habitats(valley, north and south slopes). The relative abundance of Glomeromycota in the valley was significantly higher than that in other three habitats(north and south slopes and top hill).(2) Soil attributes accounted for 20% of the variation in soil fungal richness, with soil fungal richness associated positively with soil pH, total nitrogen and available nitrogen, but negatively with soil organic carbon, soil organic matter and C/N ratio. No significant correlation was found between soil fungal Shannon index and soil attributes.(3) CWM of five traits accounted for 21% of variation in soil fungal richness, with soil fungal richness correlated negatively with CWM of plant height.(4) FD of five traits accounted for 33% of variation in soil fungal richness, which increased with FD of leaf nitrogen and leaf phosphorus but declined with FD of plant height and leaf dry matter content. Neither CWM nor FD significantly correlated with soil fungal Shannon index. The soil fungal richness, rather than Shannon index, was not only associated with soil attributes but also with plant community functional traits. The interaction between soil fungal richness and FD plays an important role in promoting ecosystem stability in alpine meadows.