| Global warming accelerates the hydrological cycle,thereby changing future precipitation patterns in most regions.Precipitation is an important water source for arid and semi-arid ecosystems,and a key driver of various biological processes at different spatial and temporal scales.Soil fungi are not only important participants in soil nutrient cycling,but also have symbiotic or parasitic relationships with plant roots,which are crucial for assessing soil carbon storage and improving plant productivity.However,the conclusion about soil fungal community characteristics under precipitation changes is still controversial.As a transitional ecogeographical unit between grassland and desert,the desert grassland in western Loess Plateau plays an irreplaceable role in maintaining the stability of ecosystem.Therefore,analyzing soil fungal community characteristics under precipitation changes in desert grassland of western Loess Plateau is of great significance for assessing vegetation restoration and stability maintenance in desert grassland under climate change.In this study,a field precipitation manipulation experiment was conducted in desert grassland of the western Loess Plateau,set up five precipitation treatments,namely,40% decrease in precipitation(DP40),20% decrease in precipitation(DP20),control(CK),20% increase in precipitation(IP20),and 40% increase in precipitation(IP40).After collecting soil samples of different precipitation gradients,high-throughput sequencing method combined with FUNGuild database was used to obtain the data of soil fungal community characteristic,such as community composition,diversity and functional groups,and variance analysis,structural equation model and other analysis methods were used to analyze characteristics and influencing mechanism of soil fungal community in desert grassland under precipitation changes.The main study results are as follows:(1)Only soil fungal Shannon diversity of desert grassland in IP20 treatment was significantly lower than that in CK.However,the strong sensitive of fungal βdiversity to altered precipitation indicates that precipitation changes led to great differences in soil fungal community composition among different habitats in desert grassland.(2)Precipitation changes significantly affected the soil dominant fungal community composition in desert grassland.Ascomycota and Basidiomycota,as the most dominant fungal groups,were markedly enriched in DP40 and IP20 treatments,respectively.Ascomycota,as a typical representative of drought-tolerant groups and key species,was closely relate to fungal community function groups,which indicated that soil fungi can better adapt to arid environment,thereby maintaining the function of desert grassland ecosystem.(3)Plant pathogen fungi was markedly enriched in DP40 treatment,arbuscular mycorrhizal fungi was significantly abundant in IP40 treatment,which indicated that the frequency of fungal diseases caused by plant pathogen was higher under decreased precipitation,while plant mutual symbiosis activity was stronger under increased precipitation in desert grassland.In addition,DP40 treatment reduced the number of modules in the co-occurrence network,increased the total number of edges and the average degree of the network,indicating that drought shaped lower functional diversity and more complex network of soil fungal community in desert grassland.(4)DP40 treatment significantly reduced plant coverage,plant density and aboveground biomass,increased soil available phosphorus,nitrate nitrogen and electrical conductivity.Correlation analysis showed that available phosphorus,electrical conductivity and plant coverage were closely related to soil fungal community characteristics.Structural equation model analysis showed that changes in soil properties caused by altered precipitation did not only directly affect soil fungal community composition and function,but also indirectly change fungal community function by regulating fungal community composition. |
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