Change Characteristics Of Soil Organic Carbon In Shiyang River Basin And Its Response To Climate And Landuse Changes

Under the influence of global climate change and human activities,the spatial distribution of soil organic carbon has different rules.As an important index of soil fertility evaluation,soil organic carbon plays an important role in carbon sequestration.To clarify the distribution and change of soil organic carbon is of guiding significance for environmental protection and management and agricultural operation.Using geostatistics and optical remote sensing method to estimate soil organic carbon is one of the important methods to study soil organic carbon.This method can reflect the distribution and variation of soil organic carbon in a large area with fewer sampling points,and is an important method to study soil organic carbon at present.In this paper,the Shiyang River Basin in the inland arid region is taken as the research area,using the measured surface(0~20 cm)soil profile data and 2019,and2013 Landsat8 OLI remote sensing image,based on GIS and remote sensing technology to establish inversion model of Shiyang River Basin,the surface soil organic carbon,estimate the Shiyang River Basin in 2013 and 2019,the two phase of the surface soil organic carbon density and reserves,to analyze its change rule and influence factors,and use the model will InVEST climate and land use change on soil organic carbon,to quantify the influence of the main conclusions are as follows:(1)In 2013,the average surface soil organic carbon density was 2.94 kg/m~2 and the reserves were 118.47 Tg.In 2019,the average surface soil organic carbon density was3.08 kg/m~2 and the reserves were 122.68 Tg,showing an increasing trend with a growth rate of 0.7 Tg/a.Among the four land use types,forest land has the highest surface soil organic carbon density,followed by grassland and arable land,and unused land has the lowest soil organic carbon density.(2)From 2013 to 2019,the proportion of soil carbon sink function unchanged area in Shiyang River Basin river basin was the largest,accounting for 79.46%,the proportion of carbon sink function enhanced area accounted for 13.87%,mainly distributed in the desert area on the edge of the oasis in the middle and lower reaches of the basin,and the proportion of carbon sink function weakened area accounted for6.67%,mainly distributed in the wuwei oasis and minqin oasis in the middle and lower reaches and their vicinity.(3)The changes of surface soil organic carbon density and reserves in Shiyang River Basin river basin are the result of climate and land use changes.Soil organic carbon increased with the increase of annual precipitation.The soil organic carbon density increased by 52.13%,44.65%and 78.34%after the conversion of cultivated land,grassland and unused land into forest land,respectively.The soil organic carbon density increased by 13.52%,60.86%and 54.74%after the conversion of cultivated land to grassland,unused land to grassland and unused land to arable land,respectively.The contribution rate of land use change to soil organic carbon storage is48.93%,and that of climate change is 51.06%.The contribution rate of land use change to the actual soil organic carbon storage in the upstream area is 52.73%and that of climate change is 47.26%.The contribution rate of land use change to the actual soil organic carbon storage in the middle reaches was 41.03%and that of climate change was 58.97%.The contribution rate of land use change is 54.62%and that of climate change is 45.38%.From 2013 to 2019,climate change and land use change play a positive role in promoting the carbon sink of Shiyang River Basin with similar contributions.Projects such as returning farmland to forest and grassland and ecological water diversion have improved the overall ecological environment of the watershed,and the soil organic carbon density and reserves have increased.