Soil Physical And Chemical Properties And Quality Evaluation Of Different Land Use Types In Qinghai Tibet Plateau

In recent years,the alpine grassland ecosystem on the Qinghai-Tibet Plateau has been seriously degraded due to climate change and intensified human activities.The Tibetan Plateau is rich in natural resources and unique natural conditions,and the unique climatic environment of alpine grassland makes it difficult to recover after degradation.Therefore,this study investigates the soil of the Tibetan Plateau to understand the changes of soil physicochemical properties and provide a theoretical basis for protecting the ecological environment of the Tibetan Plateau.In this study,alpine meadow grassland,scrub meadow grassland,desert grassland,forest land and agricultural land were selected to explore the physical properties and nutrient characteristics of soils on the Tibetan Plateau under different land use patterns,and to assess the soil quality of the study area,which is important for studying regional ecological security and sustainable development.The specific research results are as follows:(1)In the 0-30 cm soil layer,soil total nitrogen,organic matter,total phosphorus,fast-acting phosphorus,fast-acting potassium,nitrate nitrogen and ammonium nitrogen all decreased with increasing soil depth,and the overall soil nutrient content in the five different land uses showed: alpine meadow grassland > scrub meadow grassland > forest land > desert grassland > agricultural land.Soil conductivity,capacitance and p H increased with soil depth in the 0-30 cm soil layer,and soil capacitance and conductivity of agricultural land were significantly higher than the rest of the land use methods.Soil p H in the five different land use methods ranged from 6.86 to 8.03,and soil p H was weakly alkaline.(2)The differences in soil physicochemical characteristics were significant(P < 0.05)in the north and south under the five land use methods.Soil organic matter,total nitrogen,fast-acting phosphorus,fast-acting potassium,electrical conductivity,and p H were significantly higher in the north than in the south,and soil total phosphorus content showed significantly lower in the north than in the south.In the 0-30 cm soil layer,C:N,C:P and N:P were highest in the northern part of the Tibetan Plateau in woodland,and the highest C:N in alpine meadow grassland and the highest C:P and N:P in woodland in the south.Soil bulk,p H,conductivity,fast-acting phosphorus,organic matter,and total phosphorus were highly significantly correlated with C:N.Soil bulk,nitrate nitrogen,ammonium nitrogen, fast-acting potassium,organic matter,total phosphorus,and total nitrogen were highly significantly correlated with C:P and N:P.Among them,soil organic matter and soil bulk were the main factors affecting soil ecological stoichiometry values in this region under five land use patterns.(3)The minimum data set method was used to evaluate soil quality under five types of land use in the Qinghai-Tibet Plateau region,and the minimum data set was established by combining the affiliation function method and the comprehensive soil quality index to filter out the key indicators for evaluating soil quality.The selection of soil quality indexes in the minimum dataset is high for soil organic matter,total phosphorus,nitrate-nitrogen and electrical conductivity.Soil quality indices in the northern part of the Tibetan Plateau showed: scrub meadow grassland(0.56)> forest land(0.55)> alpine meadow grassland(0.54)> desert grassland(0.52)> agricultural land(0.47),and soil quality indices in the southern part showed: scrub meadow grassland(0.57)> alpine meadow grassland(0.55)>forest land(0.52)> desert grassland(0.50)> agricultural land(0.48).The soil quality grade of desert grassland and agricultural land is Ⅲ,and the soil quality of scrub meadow grassland,alpine meadow grassland and forest land is Ⅳ.Organic matter is the key index limiting the soil quality in this area.