ObjectiveThis study aims to explore the diversity and community structure of soil fungi in different stages of Napahai Plateau Wetland of northwestern China, and reveal the response rule of soil fungi to wetland degradation.

MethodWe analyzed composition, structure and Alpha diversity of soil fungal community, and relationships between fungal community structure and soil physical and chemical factors at different degradation stages in Napahai Plateau Wetland, by using Illumina high-throughput sequencing techniques and primary swamp as control.

Result(1) The composition and structure of soil fungal community were different among varied degradation stages. Soil fungi belonged to five fungal groups, including Ascomycota, Basidiomycota, Chytridiomycota, fungi-unclassified and Zygomycota. Among them, Ascomycota had the highest relative abundance in the meadow wetland (71.11%), unclassified fungi had the highest relative abundance in primary swamp (85.26%), Basidiomycota had the highest relative abundance in swamp meadow (26.8%), Zygomycota had the highest relative abundance in the reclaimed wetland (39.34%). The cluster analysis showed that the fungi community structure and composition between the swamp meadow and the primary swamp were similar to each other, while the ones between meadow and reclaimed wetland were significantly different. The main dominant fungal groups changed from fungi-unclassified to Ascomycetes, Basidiomycetes and Zygomycota as degradation changed from primary swamp to swamp meadow, meadow and reclaimed wetland. (2) There were significant differences (P < 0.05) in soil fungal Alpha diversity among different degraded stages, and showing an increasing trend in diversity as degradation aggravated. The order of diversity indices (Chao1, Ace, Shannon) was reclaimed wetland (671.43, 685.84, 3.93) > meadow(522.25, 534.22, 3.58) > swampy meadow(387.80, 391.37, 3.48) > primary swamp(379.17, 380.56, 3.12). The Simpson index presented the trend of reclaimed wetland (0.079) < meadow (0.081) < swampy meadow (0.092) < primary swamp (0.107). (3) RDA and Pearson correlation analyses showed that soil water content, organic matter, total nitrogen, C/N ratio, available nitrogen and pH significantly affected the structure and diversity of soil fungi community at different degradation stages.

ConclusionThere are significant differences in soil fungal community structure and species diversity in different degradation stages. Physical and chemical factors such as soil water content and organic matter have great influence on the diversity and community structure of fungi. The results can provide data and theoretical support for wetland protection and restoration in degraded plateau.