Seasonal Dynamicsof Soilmicrobes In Different Vegetation Types In Jinhua Mountain

Soil microbes play a key role in the regulation of soil nutrient cycling and plant growth in forest ecosystems.Jinhua Mountain is located in Jinhua City,Zhejiang Province in the eastern subtropical zone.It is a typical subtropical forest ecosystem.Its special geographical environment and climatic conditions have enriched its rich biological resources.Vegetation,plant community and fauna,plant diversity and niche of Jinhua Mountain have been reported;soil animals also have been reported,but so far,there has been no research on soil microbial diversity in Jinhua Mountain.In this study,six vegetation types in Jinhua Mountain(evergreen broad-leaved forest,deciduous broad-leaved forest,coniferous and broad-leaved mixed forest,Chinese fir forest,masson pine forest,and secondary shrub)were selected as research objects,and high-throughput sequencing techniques were used to analyze seasonal dynamics of soil microbial community composition and diversity in different vegetation types.Combined with plant diversity and soil physical and chemical factors,using Pearson correlation and RDA redundancy analysis,the relationships between soil microbes and aboveground vegetation diversity,soil physical and chemical properties were investigated to explore the mechanisms of affecting soil microbial community composition and diversity.The main findings are as follows:(1)The soil bacterial OTUs and Shannon index were the highest in the deciduous broad-leaved forest in the four seasons;the soil bacterial Chao1 index was the highest in the Chinese fir forest in spring and summer and the highest in the deciduous broad-leaved forest in autumn and winter;the soil bacteria Simpson index was the highest in the evergreen broad-leaved forest in autumn and winter.The soil fungi OTUs were the highest in the Chinese fir forest in spring and summer.The soil fungi Chao1 index was the highest in the Chinese fir forest in spring and the highest in the evergreen broad-leaved forest in autumn.The soil fungi Shannon index was the highest in the Chinese fir forest in spring and summer,however,it was the highest in evergreen broad-leaved forests in autumm and winter.The soil fungi Simpson index was high in the Chinese fir forest in spring and autumn,but there was no significant difference among six vegetation types in summer and winter.The diversity of soil bacteria and fungi in different vegetation types also changed with the seasons,and the variation rules were inconsistent.(2)The dominant microbes of different vegetation types in the same season was similar,but their relative abundance was different.The relative abundance of Proteobacteria was the highest in coniferous and broad-leaved forests in spring and the highest in deciduous broad-leaved forests in autumn,and the highest in coniferous and broad-leaved mixed forests in winter.The relative abundance of AD3 of the four seasons in the evergreen broad-leaved forests was the highest.In the three seasons of spring,summer,and autumn,the relative abundance of Actinobacteria in Pinus massoniana forest was high,but the relative abundance in winter was significantly lower than that in the other five vegetation types.The relative abundance of Agaricomycetes of four seasons was the highest in deciduous broad-leaved forests;the relative abundance of Dothideomycetes was the highest in pine forest in spring,summer and winter;the relatives abundance of Leotiomycetes are high in Chinese fir forest in summer and winter.The relative abundance of soil-predominant bacteria and fungi in most vegetation types did not change significantly with the seasons.(3)Soil bacterial OTUs and their diversity indices were not significantly correlated with the diversity indices of aboveground plants.There was a significant negative correlation between soil fungal OTUs and aboveground vegetation species variability(Shannon index)and dominance(Simpson index).Soil fungal species diversity Chao1 and aboveground vegetation species dominance(Simpson index)showed a significant negative correlation.(4)There was a significant positive correlation between soil pH and soil bacterial OTUs and various diversity indices.Soil conductivity was significantly negatively correlated with soil bacterial OTUs and Shannon index.Soil pH,organic matter,and total nitrogen content were positively correlated with soil fungi OTUs,Chao1 and Shannon index.Soil conductivity and organic matter content also showed a significant positive correlation with soil fungi Simpson index.(5)RDA analysis of soil microorganisms and soil factors showed that the composition and diversity of soil bacterial community were mainly driven by ammonium nitrogen and total nitrogen,while the composition and diversity of soil fungal community were mainly driven by soil pH and total nitrogen.