Response Of Carbon Pool Distribution In Dongchuan Debris Flow Area To Land Use Type And Landscape Inde

Debris flows are a relatively frequent geological disaster in the mountains of southwest China.The Xiaojiang River Basin in Dongchuan,Yunnan Province,is a typical area where debris flows occur.Terrestrial ecosystems are a huge carbon pool.Whether it is environmen-tal degradation or global changes such as the greenhouse effect,they are inseparable from the global carbon cycle.Remote sensing technology is the most commonly used method to study carbon cycle in recent years.In the study of soil carbon cycle,remote sensing technol-ogy is mainly used to obtain the land use type and vegetation dynamics at the macro scale to study the change of soil carbon pool.Changes in land use can cause a series of changes in soil properties and ecological quality,such as changes in soil carbon pool and water content.Soil quality is an important factor affecting land use and ecological restoration in debris flow areas.Therefore,research on the relationship between soil carbon pool distribution and land use in debris flow areas is of great significance for local productivity restoration and land spatial distribution.This paper selects the Jiangjiagou debris flow area and the Tie Jiangwangou debris flow area across the small river in the Dongchuan area for comparative research,and divides the two small watersheds into three areas:formation area,circulation area and accumulation area according to their spatial distribution characteristics.Based on the spatial differentiation characteristics of soil carbon pools in each region,combined with the differences in land use structure characteristics in the basin where each debris flow area is located,the response characteristics of soil carbon pools in debris flow areas to land use were analyzed.Among them,the area of Jiangjiagou small watershed is 52.39 km~2,the area of the small watershed of Tiejiangwangou is 41.15 km~2.The main methods of research and application are:A.On the basis of field investigation,by using the"3S"technology platform,the land use type database of the two small water-sheds is established;B.The soil sampling was carried out in the debris flow formation area,circulation area and accumulation area according to different land use types.The sampling depth was set to 0-10 cm,10-20 cm,20-40 cm,and the soil carbon pool test indicators were organic carbon(SOC),inorganic carbon(SIC)and total carbon(STC);C,Statistical analysis software was used to analyze the correlation between land use pattern and SOC,SIC and STC.Main findings:A.Distribution characteristics of soil carbon pools in the two watershedsIn the accumulation area of debris flow,the organic carbon content in the mud-rock flow flatland in front is more abundant,and these soils are the topsoil brought down in the process of debris flow movement.In the same area and depth of the debris flow in Jiangjiagou and Tiejiangwangou,respectively,under different land use types.There were significant differences in SOC,SIC and STC contents.There were significant differences in STC content in different debris flow areas under the same land use type(P<0.05).B.Characteristics of land use patterns in the two watershedsThe total area of land use pattern index(CA)and the proportion of landscape area oc-cupied by patches(PLAND)in Jiangjiagou watershed are higher,so the scale of debris flow in Jiangjiagou is larger than that in Tiejiangwangou.The ratio of perimeter to area(PARA＿MN),the proportion of landscape area occupied by patches(PLADJ),the patch con-nectivity index(CONNECT),and the aggregation index(AI)in the Tiejiangwangou Valley watershed were relatively high.Compared with the Tiejiangwangou,the Jiangjiagou debris flow beach has a larger area,but it is relatively fragmented and the aggregation degree is not high.C.Influence characteristics of land use on SOC,SIC and STCSOC and SIC are affected by land use type and water content,thereby potentially af-fecting soil carbon storage.The depth of the soil layer and the type of land use all affect the content of soil carbon pool and soil moisture content.There were significant differences(P<0.05)between the contents of soil carbon pools under the same land use type.D.Response characteristics of carbon pools to land use patternsIn the 0-10 cm,10-20 cm and 20-40 cm soil layers,the land use pattern indices CA,PLAND and AI all had negative correlations with the contents of SIC and STC,and the correlation level was 0.05.The indices PLADJ,CONNECT,COHESION and SPLIT had a negative and extremely significant correlation with SIC and STC content,and the correlation level was 0.01.E.Suggestions for ecological restorationBased on the results of the study,we suggest that peach tree(Amygdalus persica L),blue eucalyptus(Eucalyptus globules)and bitter thorn flower(Solanum deflexicarpum C.Y.Wu et S.C.Huang)as plants to increase soil carbon content in the study area.