Study On Soil Microbial Community Structure Under Different Vegetation Restoration Models In Rocky Desertification Area

The karst area is dominated by agricultural economy,and the irrational exploitation and utilization of land resources have caused serious land degradation.Therefore,a series of measures have been taken to control the rocky desertification in this area,one of the important measures is to return farmland to forest and grassland.Walnut forest is an important economic forest crop in this region,and ryegrass is widely used as an important feed for farmers to keep livestock.Creek in guizhou bijie Sarah demonstration area as the study area,with walnut,ryegrass,abandoned land as the research object,cultivated land-corn as reference,the essay analyzes the status quo of soil microorganisms under different vegetation conditions,the use of high-throughput sequencing technologies and indoor experiments on soil microbial community distribution characteristics,influence factors and function were studied.In order to provide decision-making basis for ecological restoration and economic construction in karst areas,the main conclusions are as follows:(1)Under different vegetation conditions,the bacterial community Shannon index showed maize > rye > abandoned field > walnut,Ace index showed maize > ryegrass >abandoned field > walnut,Chao index showed maize > ryegrass > abandoned field >walnut,and Coverage index showed walnut > ryegrass > abandoned field > corn.The results showed that the Shannon index of fungal community was walnut > corn >ryegrass > abandoned land,Ace index was ryegrass > walnut > corn > abandoned land,Chao index was ryegrass > walnut > corn > abandoned land,and Coverage index was maize.Walnut > abandoned field > ryegrass.According to Kruskal-Wallis rank sum test,bacteria and fungi had significant differences in different genera.NDMS analysis showed that there were significant differences between rich and rare soil microbial communities under different vegetation conditions.(2)In different vegetation restoration plots,organic carbon was the most important soil environmental factor for bacterial and fungal communities,and the effect of organic carbon on bacterial communities in abandoned plots was greater than that in other plots.The effect of p H value on the bacterial community of walnut plot was greater than that of other plots.The effect of total nitrogen on bacterial community in maize and abandoned plots was greater than that in other plots.The effects of available nitrogen,available potassium and water content on bacterial community in maize plots were greater than those in other plots.The effects of soil organic carbon,available P,total P and available K on fungal community in abandoned plots were greater than those in other plots.The influence of p H value and water content on fungal community was greater than that of other plots.There was a significant positive correlation between actinomycetes and sucrase,and a significant negative correlation between Firmicutes and urease and sucrase.Basidiomycota and phosphatase showed significant positive correlation.(3)based on BugBase phenotypic projections for bacteria,phenotypic differences under different vegetation conditions,and the facultative anaerobic bacteria,potential pathogens,and mobile elements are significant differences,the relative abundance of facultative anaerobic bacteria of walnut > abandoned land > perennial ryegrass > corn,the relative abundance of the pathogenic bacteria of abandoned land > perennial ryegrass > walnut > corn,The relative abundance of moving elements was maize >walnut > ryegrass > abandoned land.In addition,the relative abundance of gram positive bacteria is corn > walnut > perennial ryegrass > abandoned land,the relative abundance of the gram-negative bacteria of abandoned land > perennial ryegrass >walnut > corn,aerobic bacteria of the relative abundance of walnut > perennial ryegrass >corn > abandoned,the performance of the anaerobic bacteria for perennial ryegrass >corn > abandoned land > walnut,The relative abundance of biofilm formation was walnut > ryegrass > maize > abandoned land.Correlation analysis showed that the abundance of beneficial functional groups in walnut plot was higher than that in other plots,and the abundance of pathogenic bacteria functional groups in abandoned plot was higher,suggesting that proper management should be considered to promote the development of beneficial functional groups during vegetation restoration.(4)Functional annotation prediction based on FAPROTX showed that there were significant differences in its functions.The ratio of heterotrophic type was corn >walnut > ryegrass > abandoned field,the ratio of nitrogen fixation type was walnut >ryegrass > abandoned field > corn,and the ratio of Chitinolysis type was corn >ryegrass > abandoned field > walnut.The results showed that the proportion of bacteria with nitrogen-fixing function and chemical energy heterotype could be increased by strengthening management.(5)Based on FUNGuild prediction of fungal functional groups,the saprophytic groups of walnut and ryegrass were higher than those of other plots,while the pathophytic groups of abandoned plots and maize plots were higher than those of other plots.In the process of vegetation management,it is necessary to strengthen management measures to promote the development of soil fungal structure to beneficial flora.The results showed that under different vegetation restoration modes,walnut mode had the best functional status of soil microbial community,which was suitable for spreading in rocky desertification control area.Ryegrass mode had better functional status of soil microbial community,while abandoned land mode had stronger development of pathogenic bacteria due to lack of management.For different vegetation restoration modes,management should be strengthened,which can improve the proportion of soil microbial beneficial flora and improve the quality and efficiency of soil restoration by adjusting the input of soil nutrients such as carbon,nitrogen and phosphorus.