Effects Of Vegetation Restoration On Soil Microecological Environment In Tableland Slope Of Loess Plateau Gully Region

In this experiment,the eroded slope of Xifeng district,Qingyang City,Gansu Province,located in the Loess Plateau Gully area was taken as the research area.Four sloped farmlands abandoned for 0,5,10,and 20 years and three types of plantations?Pinus tabulaeformis,Armeniaca sibirica,and Robinia pseudoacacia plantation?were selected as experimental sites.Effects of restoration types and stages on soil micro-ecological environment were analyzed.Based on vegetation properties,the soil quality was evaluated.Results showed that:1.Different types of vegetation restoration have significant effects on soil properties.Soil total organiccarbon?TOC?,total nitorgan?TN?,nitrate nitorgan?NO₃^--N?contents,the activity of?-glucosidase,cellulase,urease and alkaline phosphatase increased with vegetation restoration,while available phosphorus?AP?decreased.The contents of total organic carbon?TOC?,total nitorgan?TN?,total phosphorus?TP?and ammonium nitrogen?NH₄⁺-N?in different afforested lands were significant higher than control.2.There were significant differences in soil mechanical composition and agglomerate structure of different vegetation restoration types.In the natural restoration plots,the clay content,mean weight diameter?MWD?and geometric mean diameter?GMD?of the soil water-stable aggregates was increased with the recovery period increases,which were the highest in the natural recovery 20-year plot.While the sand content was gradually decreasing.In different afforested lands,the content of clay was significantly higher than that in the control group,the sand content was significantly lower than the control group.Among them P.tabulaeformis plantation had the highest clay content and the smallest sand content.3.Soil bacterial and fungi communities under different vegetation restoration types were determined by Illumina HiSeq sequencing method.Restoration types had no significant effect on soil microbial communities.Proteobacteria,Actinobacteria and Acidobacteria were the main phylain of soil bacterial communities.Zygomycota,Basidiomycota and Ascomycota were the dominant phyla of fungi communities.With the changed of restoration types and restoration period,the relative abundance of microbial communities also changed significantly.The relative abundance of Actinobacteria gradually decreased with longer successition stage,while the relative abundance of Proteobacteria increased gradually.In different afforested lands,the relative abundance values of Proteobacteria and Acidobacteria were significantly higher than control.The relative abundance of Actinobacteria was significantly lower than that of the controlgroup.RDA analysis showed:Bacterial community was mainly affected by herb diversity index,total phosphorus?TP?and total organiccarbon?TOC?during the natural recovery stage.The shurb biomass,nitrate nitrogen?NO₃^--N?and N/P ratio in different afforested lands were the main influencing factors.Fungi community was mainly affected by shurb diversity index,total organiccarbon?TOC?and nitrate nitrogen?NO₃^--N?of the natural recovery stage.The shurb biomass and C/N ratio had a stronger effect on fungi community in different afforested lands.In addition,Ascomycota,Basidiomycota and Nitrobacterium had significant effects on soil erodibility.4.Principal Component Analysis was used to evaluate the soil quality of different restoration types baesd on chemical,physical,biological and other soil characteristics.The comprehensive evaluation values of soil quality were ranked:A.sibirica plantation>R.pseudoacacia plantation>20-year natural recovery>P.tabulaeformis plantation>10 year>5 year>wasteland.Plantation had a better effect on soil quality.In summary,natural restoration and plantation could increase vegetation coverage and diversity,improve soil erosion resistance,microbial diversity and activity.They are effective measures to control soil erosion in the Loess Plateau Gully Region.