Study On Distribution Characteristics And Influencing Factors Of Soil Carbon,Nitrogen,Phosphorus And PH Value In Alpine Grassland Of Upper Yellow River

Soil is the core element of the earth's key zone,which controls the flow and transformation of matter,energy and information in the earth's key zone,and has a significant impact on each component of the ecosystem.The Qinghai-Tibet Plateau,known as the " world roof of the world",is a typical ecologically fragile region and climate change sensitive zone.It is the region with the largest alpine grassland area and the most types in the world,which has a great impact on the earth system and social ecosystem.Soil is the matrix of interaction between organisms and environment in the ecosystem,and is the bed for propagation and expansion of plants in alpine grassland.It stores a large amount of nutrients.Soil fertility characteristics are the key factors that determine the stability of grassland ecosystem structure and function.Based on the data of 10 sampling points in Henan,guinan and zeku counties in the southeast of Qinghai province,the effect and influence of composite factors on soil nutrient content and PH value were discussed by using geograPHic detectors on the contribution of altitude,slope,aspect,topographic relief,precipitation,temperature,aboveboar 0 ? accumulated temperature,above 10? accumulated temperature,vegetation type and soil type to soil nutrient content and PH value.The main conclusions are as follows:(1)There were significant differences in soil nutrient content and PH value among different vegetation types.Soil organic matter content showed as follows: Carex capillifolia meadow > Kobresia tibetica+Carex sadoensis meadow > Kobresia parva meadow > Stipa purpurea steppe > Orinus kokonorica steppe >Stipa aliena steppe > Kobresia parva + Kobresia humilis meadow,which the corresponding soil is: meadow soil,straw mat soil,chernozem,dark mat soil,chestnut soil;soil total nitrogen content of different vegetation types was Carex capillifolia meadow > Kobresia parva meadow > Stipa purpurea steppe > Kobresia tibetica+Carex sadoensis meadow > Orinus kokonorica steppe > Stipa aliena steppe > Kobresia parva + Kobresia humilis meadow,which the corresponding soil is meadow soil,chernozem,dark mat soil,straw mat soil,chestnut soil;Soil total phosphorus of different types of vegetation showed that: Kobresia tibetica,Carex sadoensis meadow > Stipa purpurea steppe > Stipa aliena steppe > Carex capillifolia meadow > Orinus kokonorica steppe > Kobresia parva meadow > Kobresia parva + Kobresia humilis meadow,which the corresponding soil is: meadow soi,chernozem,straw mat soil,dark mat soil,chestnut soil;The soil PH values of different vegetation types were as follows: Kobresia parva + Kobresia humilis meadow > Stipa aliena steppe > Orinus kokonorica steppe > Stipa purpurea steppe > Carex capillifolia meadow > Kobresia parva meadow > Kobresia tibetica,Carex sadoensis meadow,which the corresponding soil is: chestnut soil,dark mat soil,chernozem,straw mat soil,meadow soil.(2)Soil nutrients,pH value and environmental factors have significant influence relations,and different environments have great differences in their effects.Soil organic matter content is positively correlated with altitude,slope of the region,regional precipitation and soil type,but negatively correlated with aspect,accumulated temperature above 0? and above 10?,annual average temperature,vegetation type and topographic relief.Total nitrogen content in soil is positively correlated with altitude,slope,aspect,topographic relief and vegetation type in the region,but negatively correlated with accumulated temperature above 0 ? and above 10 ?,regional precipitation,annual average temperature and soil type.Total phosphorus content is positively correlated with altitude,slope of the region,regional precipitation,topographic relief,vegetation type and soil type,but negatively correlated with aspect,average annual temperature,above 0? and above 10? accumulated temperature.Soil PH is positively correlated with aspect,above 0? and above 10? accumulated temperature and annual average temperature,but negatively correlated with altitude,aspect,topographic relief,vegetation type and soil type.(3)The spatial heterogeneity of soil nutrients and PH is the result of the coupling effect of soil conditions and environmental factors.It is mainly affected by the comprehensive effects of topographic factors(altitude,slope,aspect,etc.),climatic factors(temperature,precipitation,accumulated temperature),vegetation types and soil types.Among them,altitude,slope,aspect,above 0? accumulated temperature and annual precipitation contribute the most,all being 1,which shows that the spatial heterogeneity distribution of soil nutrient content and PH value can be fully explained,and the spatial distribution of organic matter is dominated with the strongest consistency,followed by vegetation type,annual average temperature,above 10? accumulated temperature,topographic relief degree and soil type.(4)The spatial variability of soil nutrient content and pH value is the result of the combined action of various environmental factors(altitude,slope,aspect,topographic relief,precipitation,temperature,above 0? accumulated temperature and above 10? accumulated temperature).The interaction between different environmental factors is significantly different.When two environmental drivers suitable for soil nutrient accumulation and pH value increase are superimposed,their comprehensive influence on the spatial heterogeneity distribution of soil nutrient content and pH value is enhanced,revealing the diversity and complexity of the influencing factors of the spatial heterogeneity distribution of soil nutrient and pH value.