Effects Of Desertification On Soil Organic Carbon And Soil Inorganic Carbon In Desert Grassland

The ability of desert grassland ecosystem to self-repair is very fragile.In recent years,a large number of studies have focused on vegetation communities and soil nutrients in the process of grassland desertification,while little research has been done on the effects of desert grassland desertification on soil inorganic carbon(SIC).Therefore,this study takes the desert grassland in different desertification stages of Yanchi County in central and northern Ningxia as the research object,and by spatial method instead of time method to study the changes of soil organic carbon(SOC)and soil inorganic carbon(SIC)in different desertification stages of desert grassland.The effects of desertification on the distribution of soil organic carbon and soil inorganic carbon content,soil organic carbon and soil inorganic carbon density of different particle size components and soil carbon isotope values.Reveal the response mechanism of soil carbon pool to the desertification of desert grasslands in order to provide a theoretical basis for the study of global carbon cycle.The results shows that:(1)The soil inorganic carbon density(SICD),soil organic carbon density(SOCD)and soil total carbon density(STCD)in the 0-30cm soil layer of the desert grassland shows a decreasing trend with the increasing degree of desertification.Soil organic carbon and soil inorganic carbon density in Fixed dunes,Semi-fixed dunes and Mobile dunes are 18.5%and 57.7%,60.5%and 6.7%,35.9%and 47.0%,respectively,compared with desert grassland.(2)The range of soil organic carbon isotope values(?13C-SOC)and inorganic carbon isotope values(?13C-SIC)in desert grasslands are-23.1‰-20.0‰ and-3.2‰-1.4‰,respectively.The soil organic carbon isotope values in 0-30cm soil layer shows that the desertification degree of desert grasslands increase to Fixed dunes>Desert grasslands>Semi-fixed dunes>Mobile dunes,and soil inorganic carbon isotope shows Mobile dunes>Semi-fixed dunes>Fixed dunes>Desert grassland.Except for 0?10cm surface soil,the pedogenic carbonates content of soil in 10?30cm soil layer gradually decrease with the increase of desertification degree in desert grassland,and the pedogenic carbonates content in desert grassland and Fixed dunes are significant differences between Semi-fixed dunes and Mobile dunes.(3)The content of soil organic carbon and soil inorganic carbon in the 0?10cm soil layer decrease with the increase of desertification in desert grassland.Soil organic carbon and soil inorganic carbon content of Semi-fixed dunes and Mobile dunes reveal soil inorganic carbon of clay and silt(CSIC)>soil inorganic carbon of fine sand(FIC)>soil inorganic carbon of coarse sand(CIC),soil organic carbon of fine sand(FOC)>soil organic carbon of coarse sand(COC)>soil organic carbon of clay and silt(CSOC).(4)There is a significant positive correlation between soil organic carbon density and soil inorganic carbon density in 0?30cm soil layer,while soil organic carbon isotope value(?13C)and soil inorganic carbon isotope value(?13C)are significantly negatively correlated.Soil organic carbon and soil inorganic carbon content in different particle size component of 0?10cm soil layer are positively correlated with soil organic carbon.Soil inorganic carbon of coarse sand and soil organic carbon of coarse sand had the greatest influence on total soil organic carbon,while there is a significant negative correlation between soil inorganic carbon of clay and silt,soil organic carbon of clay and silt and total soil inorganic carbon content.