Soil Microbial Community Characteristics And Soil Quality Evaluation Of Hippophae Rhamnoides Forest In Water-wind Erosion Crisscross Region

In order to clarify the soil microbial community structure and soil quality spatial variability of seabuckthorn forests in the water-wind erosion crisscross region,in order to provide scientific basis and data support for the construction of forest ecological projects such as biodiversity conservation,vegetation restoration and reconstruction,and lowefficiency forest transformation in the study area.Contribute to promoting ecological protection and high-quality development in the Yellow River Basin.In this study,the seabuckthorn forest in the water-wind erosion crisscross region was taken as the research object,and the field investigation,sampling and indoor determination were carried out.High-throughput sequencing method was used to sequence the soil bacterial and fungal communities of the seabuckthorn forests in the study area.Using redundancy analysis(RDA)method to explore the correlation between environmental factors(soil and meteorological factors)and bacterial and fungal communities,and to reveal the key ecological environmental factors that caused the changes of soil microbial community structure in seabuckthorn forests in the wind-water erosion crisscross region.Through the principal component analysis(PCA)to reduce dimension and group the pre-selected indicators,and establish the minimum data set for soil quality evaluation,and compare the linear and nonlinear index of soil quality evaluation,and to explore the applicability of linear and nonlinear soil quality evaluation models in this study area.The main results are as follows:(1)There are significant differences in soil physical and chemical properties between different seabuckthorn forests(P<0.05).The total porosity,capillary water-holding capacity,electrical conductivity and organic carbon content of sea buckthorn forest soil in Wangwazi area are the highest.The contents of total nitrogen,total phosphorus and available nitrogen are the highest,the soil nitrate nitrogen content of sea buckthorn forest in Hengshan area is the highest,and the ammonium nitrogen content of sea buckthorn forest soil in Shenmu area is the highest.(2)The bacterial sequences read from soil samples of seabuckthorn forests in the study area are classified into 38 phyla,114 classes,266 orders,452 families and 942 genera.At the level of phyla classification,Actinobacteria(44.7%),Proteobacteria(23.2%)and Acidobacteria(11.3%)are the dominant bacterial communities,and their relative abundance is above 10%.At the level of class classification,Thermoleophilia(15.13%),Actinobacteria(14.51%)and Alphaproteobacteria(12.06%)are the main groups.Their relative abundances are all over 10%,and they are the dominant taxa.Soil conductivity,available phosphorus,available potassium,total nitrogen,annual average temperature and annual maximum temperature of meteorological factors have significant effects on bacterial community change(P<0.01).(3)The fungal sequences read from soil samples of seabuckthorn forests in the study area are classified into 11 phyla,44 classes,102 orders,242 families and 448 genera.At the level of phyla classification,Ascomycota is the dominant phyla.At the level of class classification,Sordariomycetes(22.74%),Mortierellomycetes(12.62%)and Dothideomycetes(10.77%)are the main groups,and their relative abundance is more than10%.Soil available potassium,organic carbon,available nitrogen,annual maximum wind speed and annual average temperature have significant effects on the changes of fungal community structure(P<0.01).(4)The minimum data set suitable for soil quality evaluation of seabuckthorn forest in wind-water erosion crisscross region are soil bulk density,capillary water-holding capacity,organic carbon and total nitrogen.The linear soil quality evaluation model based on the minimum data set can reflect the changes of soil quality more sensitive.The soil quality in the study area is between poor and medium level,and the soil quality index from large to small is Wangwazi(0.596)> Changcheng(0.549)> Shenmu(0.371)> Yuyang(0.250)> Hengshan(0.249).There is no significant difference in soil quality between the seabuckthorn forests in Wangwazi and Changcheng,while the soil quality in Yuyang and Hengshan is significantly lower than that in other areas(P<0.05).