Soil Microbial Diversity And The Effects Of Environment On It In Baiyun Mountain National Forest Park

Soil microbes play important roles in the material circulation,energy flow and information transmission of the ecosystem.However,the species composition,diversity and spatial distribution characteristics of soil microorganisms in the transition zone from warm temperate zone to north subtropical zone are still unclear.Baiyun Mountain in Henan province is a typical transition zone from warm temperate zone to north subtropical transition zone.In this study,120 soil samples were sequenced using high-throughput sequencing technology based on a 5 hm2 forest dynamic monitoring plot in Baiyun Mountain.Then the diversity,community structure and spatial distribution characteristics of soil microbes,soil microbial diversity and community composition in different humus layer habitats,in different vegetation coverage habitats and in different soil habitats,as well as the relationship between soil microorganisms and environmental factors(topographic factors and soil factors)were analyzed.The results are as follows:(1)When the soil sampling points reached 120,17 phyla,55 classes,133 orders,343 families,792 genera and 6266 OTUs of fungi were detected,and an average of 486 OTUs were detected in a single soil sample;a total of 51 phyla,173 classes,325 orders,482 families,707 genera and 12,852 OTUs were detected,and an average of 3549 bacterial OTUs were found in a single soil sample.The dominant phylum,class and order of soil fungi were Basidiomycota(71.2%),Agaricomycetes(68.38%)and Russulales(25.48%),respectively.The dominant phylum,class and order of soil bacteria was Acidobacteria(28.82%),Spartobacteria(16.05%),and Chthoniobacterales(16.05%).There were more fungal and bacterial OTU species in the valley than in the ridge.(2)According to the thickness of humus layer of each 20 m × 20 m quadrat,the120 quadrats were divided into four habitats: A(0 cm ? thickness ? 3 cm),B(3 cm <thickness ? 5 cm),C(5 cm < thickness ? 7 cm)and D(7 cm < thickness ? 9 cm),then the diversity and species composition of soil microorganisms among the four humus habitats were analyzed.The results showed that the fungal OTU species were the most in the habitat with the thickest humus layer,while the bacterial OTU species were more in the two habitats with medium thickness of humus layer.The species richness and Shannon diversity of fungi and bacteria increased with the thickening of humus layer.There were significant differences in bacterial Alpha diversity,and significant differences in fungal and bacterial Bata diversity among the four humus habitats.The dominant phyla and dominant families of soil microorganisms among the four humus habitats were consistent,but the relative abundance of them was different.(3)According to the vegetation coverage of each 20 m × 20 m quadrat,the 120 quadrats were divided into four habitats: A(0% ? coverage < 25%),B(25% ? coverage< 50%),C(50% ? coverage < 75%)and D(75% ? coverage ? 100%),then the diversity and species composition of soil microorganisms among the four habitats were analyzed.The results showed that the OTU species of soil fungi and bacteria were the highest in the habitats with vegetation coverage of 50%~75%,and both the species richness and Shannon diversity of soil fungi and bacteria were the highest in the habitat with vegetation coverage of the highest.There was significant difference in fungal Alpha diversity among the four vegetation coverage habitats,but no significant difference in bacterial Alpha diversity.(4)According to the soil nutrient content of each 20 m × 20 m quadrat,120 quadrats were divided into three habitats: A(soil with medium nutrient),B(soil with poor nutrient)and C(soil with rich nutrient),then the microbial diversity and community composition among the three soil habitats were analyzed.The results showed that the highest number of fungal OTU species,highest Shannon diversity and species richness were detected in the soil habitat with rich nutrient,while the lowest number of fungal and bacterial OTU species,lowest species richness and Shannon diversity were detected in the soil habitat with poor nutrient.The Alpha and Bata diversity of fungi and bacteria were significantly different among the three soil habitats,and the community structure of bacteria was more different than that of fungi.(5)Redundancy analysis and correlation analysis were used to study the effects of topographic and soil environmental factors on soil microorganisms.The results showed that among the topographic factors,slope and elevation had a greater influence on soil fungal and bacterial communities,among the soil factors,p H and alkali-hydrolyzable nitrogen were the most important influencing factors,both of which had significant influence on fungi and bacteria.Soil moisture content had a significant influence on fungi,but not on bacteria.