Study On The Effect Of Soil Erosion On Soil Carbon Storage In Southwest Karst Area

The impact of soil erosion on carbon storage has been a hot issue in the fields of earth science and global change in recent years,and it is of great significance to study the dynamic changes of soil carbon storage during soil erosion and sedimentation under water erosion to evaluate the "source/sink" effect of soil carbon.Soil carbon pools are the most susceptible carbon pools,which may become either sink carbon storage or source carbon emissions.In recent years,many studies have shown that soil carbon storage is greatly affected by soil erosion,and the impact of different types of soil erosion on soil carbon storage is different,among which the impact of water erosion on soil carbon storage is more significant.The karst area of southwest China is a typical area of soil erosion with obvious erosion characteristics,so studying the impact of soil erosion on soil carbon storage in this area is of great significance to ecological control and explore the ecological cycle of karst area in southwest China.In this study,the karst areas of three provincial-level administrative units of Yunnan,Guizhou and Guangxi in southwest China were selected as the research objects,combined with the RUSLE and InVEST model carbon storage modules,and five typical surface cover system products(GL30,LULC,GLC,IGBP,CCILC)were selected to evaluate soil erosion and soil carbon storage in 2000～2020,and then explore the impact of soil erosion on soil carbon storage.The results of the study showed that:(1)The variation characteristics of soil erosion in the study area:the total amount of soil erosion decreased from 1.76×1010t(2000)to 1.52×1010t(2020),and the total amount decreased by 13.64%in 20 years;The total amount of soil erosion in the east and central China was high,the amount of soil erosion in the west and southwest was low,and the total amount of soil erosion in the second decade(total decrease was 6.81%),which was slightly lower than that in the previous decade(total amount decreased by 7.31%).In addition,the assessment results of the five land use classification methods were as follows:LULC>GL30>CCILC>GLC>IGBP,and the difference between the highest assessment result(LULC)and the lowest assessment result(IGBP)was 15%-42%,and in the Grade VI.grade,the difference between the five classification methods was the most significant;(2)Characteristics of changes in soil carbon storage in the study area:the total amount of soil carbon storage increased from 12.37PgC(2000)to 13.02PgC(2020),and the total amount increased by 5.31%in 20 years,and the total change in the following decade(total growth of 4.31%)was significantly greater than the change in the previous decade(total increase of 0.91%);In addition,the changes in the area of farmland(CL),forest land(FL)and grassland(GL)were positively correlated with soil carbon storage.In different zoning,the difference in soil carbon storage divided by the three zoning principles of "karst geomorphology","hydrogeology" and"accumulated temperature" was obvious,and the difference between the highest and lowest areas of "karst landform" was 1.08 times,1.27 times the difference between"hydrogeology" and 1.07 times.(3)The effect of soil erosion on soil carbon storage:after control experimental analysis,the impact of soil erosion on soil carbon storage is stronger(difference of 2.22～2.86 times)in areas with significant changes in soil erosion than in areas with small changes.In areas with small changes in soil erosion,the contribution of soil carbon storage changes was greater(difference of 3.50～10.50 times)in areas with small changes in soil erosion(3.50～10.50 times).In addition,land use(LULC)change(correlation 0.81),land surface temperature(GST)change(correlation-0.22),and humidity(RHU)change(correlation 0.21)were the main influencing processes affecting soil carbon storage by soil erosion.In this study,the effects of soil erosion on soil carbon storage in terms of spatial structure,regional change and multifactorial aspects were analyzed,and the optimal assessment of soil erosion was carried out by using five typical classification systems,the differences of different classification systems on soil erosion assessment were explored,and the impact of soil erosion on soil organic carbon was verified through multi-factor analysis.Studying the impact of soil erosion on soil carbon storage can better understand the mechanism of soil carbon cycle,which has a positive role in promoting carbon cycle research and exploring the potential of soil carbon sink.