三江源区退化高寒草甸土壤真菌群落特征

为了明确高寒草甸退化演替过程中土壤真菌物种组成、群落多样性及功能结构等的响应规律,本研究采用高通量基因测序技术和FUNGuild功能预测,分析了三江源区未退化、轻度退化、中度退化、重度退化和极度退化高寒草甸土壤真菌群落特征及其调控因子。结果表明: 高寒草甸土壤优势真菌为子囊菌门、担子菌门和被孢霉菌门。与未退化草地土壤相比,退化草地土壤真菌物种组成发生明显改变,草地退化后扇形枝孢菌、粉褶菌、锥形湿伞、丝盖伞菌和短梗蠕孢真菌丰度减少,三线镰孢菌和Dactylonectria macrodidyma真菌丰度增加。重度退化增加了土壤真菌Chao1指数,轻度退化则显著降低了真菌Shannon指数和Simpson指数。不同草地的病理型、共生型和腐生型真菌丰度均表现出显著差异;草地退化后土壤中的共生型真菌丰度减少,病理型真菌丰度增加。高寒草甸退化导致土壤真菌格局和功能发生明显改变,地上生物量、土壤含水量、pH、总有机碳、全氮、铵态氮、有效磷和全钾含量及有效氮磷比是改变真菌群落结构的主要驱动因子。

The characteristics of soil fungal community in degraded alpine meadow in the Three Rivers Source Region,China

To clarify the variation of species composition,diversity,and functional structure of soil fungi community along alpine meadow degradation,we examined the characteristics and controlling factors of soil fungal communities in non-degraded,lightly degraded,moderately degraded,severely degraded and extremely degraded(black soil beach)alpine meadows at the Three Rivers Source Region,based on the high-throughput gene sequencing and FUNGuild functional prediction.The results showed that the dominant phyla in alpine meadow soil were Ascomycota,Basidiomycetes,and Mortierellomycota.Species composition of soil fungal community varied greatly in alpine meadow under different levels of degradation.The abundance of Cladosporium flabelliforme,Entoloma sodale,Hygrocybe conica,Inocybe sp.and Trichocladium opacum increased,while that of Gibberella tricincta and Dactylonectria macrodidyma decreased following grassland degradation.The meadow under severe degradation had higher soil fungal Chao1 index,while that under light degradation had lower Shannon index and Simpson index.The abundance of pathologic,symbiotic,and saprophytic types of fungi varied among different alpine meadows.Along with the grassland degradation,the abundance of soil symbiotic fungi decreased,while that of pathological fungi increased.The soil fungal community and functional compositions changed obviously with degradation in the alpine meadow.Plant aboveground biomass,soil water content,pH,total organic carbon,total nitrogen,ammonium nitrogen,available phosphate,total potassium and AN/AP(ratio of available nitrogen and available phosphorus)were the main driving factors for the variations in soil fungal community structure.