Reserve Estimation And Spatial Characteristics Of Soil Origanic Carbon In Karst Katershed In The Middle Of Guizhou Province

As the largest carbon pool in terrestrial ecosystem,soil organic carbon pool has a very important influence on global climate change and human living environment.However,because of the special geological and geomorphic features and complex topographic background,the soil and its organic carbon content table in Karst area now have strong spatial heterogeneity.Taking the soil of Karst small watershed in Central Guizhou as the research object,through field investigation and indoor analysis,the total organic carbon and active organic carbon in the soil of the surface(0-20cm)and some sections of the area are analyzed,and the spatial distribution characteristics of the soil are carried out by the combination of traditional statistics and ArcGIS software.At the same time,the soil natural water content and bulk density were measured,and the soil organic carbon density was calculated with its bulk density,and then the soil organic carbon reserves were estimated.The soil organic carbon(organic carbon)under different land use types in Karst small watershed of Central Guizhou was divided and measured by the combination of soil organic carbon physical and chemical grouping method.The content of soil organic carbon in the same component.In this study,the main results obtained from the experimental data of soil samples are as follows:(1)Soil total organic carbon(SOC)and labile organic carbon(SOC)in the watershed showed high content and weak variability.The average content of soil total organic carbon is31.13g/kg,the range of change is 1.34-191.13g/kg,the average content of active organic carbon is18.00g/kg,the variation is 0.53-188.29g/kg,the variation coefficient of total organic carbon and active organic carbon content is 3%and 5%,respectively,and the total organic carbon and active organic carbon in the whole small flow field are contained.The amount of soil total organic carbon in 92.8%of soil samples is higher than that of 31.28g/kg,and the content of active organic carbon in 91.3%of soil samples is higher than 15.98g/kg.(2)The average content of total organic carbon and active organic carbon in the drainage area decreased with the deepening of the soil profile.The content of total organic carbon and active organic carbon in the soil layer of the two layers of 0-20cm and 20-40cm decreased rapidly with the gradual deepening of the soil layer,and the decrease of the content of the two layers in the soil layer under 40cm gradually became smaller and finally tended to be stable around a certain value,and the total organic carbon and active organic carbon in the surface layer(0-20cm)soil.Carbon content was the largest,34.65g/kg and 13.32g/kg respectively.(3)The analysis shows that the soil total organic carbon and active organic carbon are of moderate degree of autocorrelation,the coefficient of the bulk gold is 33.37%and 48.55%,the spatial correlation scale of total organic carbon is 389.32m,and the spatial correlation scale of active organic carbon is 319.86m.The distribution of total soil organic carbon and active organic carbon in the soil distribution pattern is basically consistent with the vegetation types and the fluctuating terrain features of small watershed.In the distribution map,the distribution of total organic carbon and active organic carbon content in the rest of the soil except for a few obvious low value areas.The patch is broken seriously,and its contour is clear.The high value area and low value area are interlaced.(4)Twelve organic carbon fractions were obtained by the combined physical and chemical grouping method.The content and size of organic carbon components in these soils were basically the same under three land use ways,and the difference between the organic carbon components was large.The main manifestations were that the organic carbon content of the unprotected coarse particles was the largest,the non acid solution particles and the clay particles were contained.The amount of organic carbon content of different components in the same land use mode was significantly different(P>0.05),and the content of organic carbon content of the same component in the three different land use modes was significantly different.With the further progress of the group steps,the content of organic carbon in most of the soil components decreased gradually.(5)The average organic carbon density of soil in small watershed is 6.45kg/m2.The average organic carbon density of paddy field,woodland and wasteland soil is 6.44kg/m~2,7.03kg/m~2,6.31g/m~2,and the average organic carbon storage of soil is 644.99kg/m~2.The average organic carbon storage of paddy soil,woodland and wasteland soil is 644.20kg/m~2,703.09kg/m~2,and631.~2,respectively.4kg/m~2.It can be seen that soil organic carbon density and soil organic carbon storage are positively correlated.