Study On Improvement Of Soil Quality Under Vegetation Restoration In Alpine Sandy Land

The soil quality changing process of desertification reversal is relatively complicated in Alpine area.With the growth of artificial vegetation restoration,sandy soil texture have different responsed processes and changed rates for different vegetation type and age.The purpose of this study is to clarify the soil quality evolution after vegetation restoration in the alpine sand area,to compare the effects of typical sand fixed vegetation on soil quality improvement and to explore the utilization potential of artificial plantations.In this study,plot placement and sample collection were performed using space instead of time,combining to test soil samples at laboratory,analyzing from the perspectives of desertification reversal stage,different vegetation types and revegetation growth years.And upon this basis,comprehensive evaluation of soil quality was conducted.The key research findings are as follows:(1)In the process of vegetation restoration prompted the desertified reversal process,from wind erosion stage to soil formation stage,the soil clay contents showed increasing,the p H showed a decreasing trend but was not significant,and soil organic matter and nutrient content gradually increasing.For one soil profile,the upper soil properties variability largest.The appearance of upper soil nutrients,soil clay content and organic matter increased significantly were the positive development symbol of soil environment.(2)Compared with the sandy dune,soil physical and chemical indexes have been significantly improved after vegetation restoration 30 years(P<0.05),soil p H is less variable among each vegetation type plots.However,different vegetation types have different effects on soil physical and chemical properties,and surface soil(0~5 cm)recovery is significantly better than the lower layer soil(15~30 cm)(P<0.05).Compared with farmland soil,the 0~5 cm soil layer of Caragana intermedia restores to a good level.(3)On the basis of establishing a soil quality assessment indexes system,using principal component analysis and correlation analysis methods,also comprehensive evaluation of soil quality improvement effect by vegetation restoration.The soil bulk density,clay,organic matter,and total nitrogen coule be used as representative indicators of soil quality in the study area.The improvement order is Caragana>Populus>Hippophae>Lycao>Salix>Tamarix.(4)During the 51 year restoration of the various vegetation types,the soil quality gradually improved with the vegetation restoration years,while its change rates showed different trends.With the soil layer depth increases,there is a time lag in the improvement effecting.The gap in soil organic matter content between different soil layers is constantly expanding.The presence of surface soil nutrients can be used as a sign of positive soil succession in alpine sandy lands,which phenomenon was appeared about 12 years after vegetation recovery,not from the initial afforestation.(5)Caragana and Hippophae are suitable for planting in Shazhuyu area of Gonghe Basin,and its have potential for exploitation and utilization after 30 years of recovery.Therefore,timely implementation of forest management measures is suggested.Ultimately,which would promote the rapid and sustainable development of forestry in the alpine sand area.