Comparisons Of Soil Fungal Diversity And Community Structure Across The Main Grasslands In Northern China

Abstrat Soil fungi, as a significant compotent of glassland ecosytem, play key roles in growth and construction of plant community and many ecological process, including nutrient cycling and energy flow, by decomposing soil organic carbon or providing nutrition for plant as symbionts. Soil fungi could act as an indicator of grassland ecosystem function and economic values, because of its sensitivity to changes of enviromental factors. For a long time, studies were conducted at local scale, little is known about whether a common set of factors govern soil fungal diversity and community structure when spatial scale varies across local, regional, even global levels. So this study set a research transect in the northern glassland of China, then investigated the changes of soil fungal diversity and community structure across different grassland types, and analyzed the response of fungi to soil physicochemical properties.In this study, a transect with five representive sites(plain meadow, meadow steppe, typical steppe, desert steppe, and alpine meadow) was established among the northern glassland of China, and the changes of soil fungal diversity and community structure and their driving forces were analyzed by high-throughput sequencing method. The results were as follows:(1) Soil fungal phyloytype richness and diversity had a significant difference across different glassland types. The changes between fungal richness and diversity were similar among these glassland types excepet plain meadow, both of which were lowest(305.05, 4.07) in the desert steppe and highest(371.08, 4.90) in the typical steppe. There was not significantly difference from fungal richness and diversity of meadow steppe, typical steppe and alpine meadow, but all of them were higher than desert steppe.(2) All valid sequences that gained from high-throughput sequencing were classified into 6 phyla and 24 classes. Soil fungi community contained Ascomycota, Basidiomycota, Glomeromycota, Zygomycota, Chytridiomycota and some unclassified fungi at the phylum level, and the first four groups were dominant fungi. The changes of relative abundance of any fungi groups except for Glomeromycota were similar, which was lower in the plain meadow and desert steppe, but higher in the typical steppe. Glomeromycota had an opposite change of relative abundance which was highest in the plain meadow. At the class level, different grassland types harbored same composition of species and dominant fungi with different relative abundance. It means a disctinct difference of soil fungi community structure among different glassland types.(3) Correlation analysis of soil fungal community characteristics and soil physiochemical properties indicated that there was no relationship between soil fungi diversity and soil physiochemical properties. Nevertheless, soil fungal phylotype richness changed along with soil miosture, organic carbon, total nitrogen and total phosphorous positively. The RDA result displayed soil fungal phylotype diversity was mainly driven by soil organic carbon. Soil available resource provided matter and energy for all kinds of organisms directly, and soil-plant-microbe formed a feedback network through bottom-up and down-top effect, that both changed the relationship of above- and under-ground interaction and community and diversity of plant and soil microbe.(4) Correlation analysis between relative abundance of soil dominant fungi and soil physiochemical properties indicated that Ascomycota had no relationship with soil physiochemical properties, but Basidiomycota and Zygomycota exhibited a singnificant or highly significant positive relationship with soil miosture, organic carbon, total nitrogen,total phosphorous, C:N ratio and N:P ratio, while a negative relationship with soil electrical conductivity and p H. Glomeromycota responsed to soil physiochemical properties in opposite tendancy with Basidiomycota and Zygomycota. The RDA result displayed soil dominant fungi was mainly driven by soil p H. Soil p H was a direct factor of fungal growth because different species had different optial p H. In addition, soil p H drived soil fungal activity and growth from different levels including above- and under-ground, which influnced plant community construction, soil available resourse and other enveronment factors that indirectly changed soil fungi.In conclusion, different grassland types contained different diversity and community of soil fungi at regional scale, which changed with environmental factors singnicantly. Especially, soil phylotype diversity was mainly drived by soil organic carbon while dominant fungi was mainly effected by soil p H. This study investigated and analysed difference of soil fungi diversity and community among different gassland types, which may enhance our knowledge about the regular pattern of soil fungi diversity and community structure and their driving forces at different space scale. In addition, it could supply us with a theoretical support to forecast ecosystem function and succession trend of grassland, and a theoretical basis which guide the realization of the ecological function and economic value of grassland as well as protection and maintenance of glassland.