Spatial Variability And Spatial Distribution Characteristics Of Soil Organic Carbon In Daxing'an Mountains

Accurate acquisition of soil organic carbon(SOC)content information,spatial heterogeneity,spatial distribution characteristics and its influencing factors and main controlling factors in the Greater Hinggan Mountains is of great significance to the regulation of soil organic carbon and the assessment of current environmental changes.In this study,the spatial variability and spatial distribution of SOC in Daxing'an Mountains(0-20cm)of Heilongjiang Province were studied by field sampling,supported by ENVI,ArcGIS,SPSS,Stata,GS + and other software.The spatial influencing factors such as topography,climate and vegetation were determined as environmental auxiliary variables.The spatial variability and spatial distribution of SOC in Daxing'an Mountains area(0-20cm)were analyzed by using the commonly used model of classical statistics and geostatistics.Based on the geographic weighted Kriging model,the main controlling factors of spatial variation of soil organic carbon content in the Great Hinggan Mountains were analyzed.1.Distribution characteristics of organic carbon content in Da Hinggan Mountains(0-20cm)are patchy in general,showing high distribution characteristics in southwest and low distribution characteristics in southeast.SOC content generally ranges from 40g/kg to 70g/kg.Distribution characteristics are relatively dispersed.The highest value of SOC content(175.73g/kg),the lowest value(11.17g/kg)and the distribution of SOC content are obvious,which means that the distribution of SOC content in Da Hinggan Mountains is obvious.There is a moderate correlation between SOC content in the study area.The spatial variability of SOC in the study area is affected by both random factors and structural factors,and the structural factors in the study of SOC in the Greater Hinggan Mountains are more than random factors.2.The spatial distribution characteristics of SOC content in Daxing'an Mountains are positively correlated with the factors affecting its spatial distribution characteristics,which are generally shown by the significant positive correlation between soil organic carbon and normalized vegetation index(0.538),land use comprehensive index(0.514),slope(0.437),slope direction(0.406).The results of principal component analysis showed that the normalized vegetation index(NDVI),comprehensive land use index(La),slope(S),slope direction(A),elevation(H)and other factors were positively correlated with SOC content.The contribution rate of the first principal component(NDVI)was 20.406%,and the cumulative contribution rate of the first,second,third,fourth and fifth principal components was 73.463%,which could better reflect the S content in Daxing'an Mountains area.Because of the spatial distribution characteristics of OC,these five factors can be used as environmental auxiliary variables for spatial prediction of SOC content.3.In this paper,geographically weighted regression Kriging model is better than regression Kriging model in spatial prediction of soil organic carbon content.Therefore,the geographically weighted regression Kriging model has better results in the study of the main factors controlling the spatial distribution characteristics of SOC content in the Greater Hinggan Mountains.4.According to the results of GWRK,only one of the explanatory variables for the spatial distribution of SOC content in Daxing'an Mountains is the control variable,namely NDVI.Compared with the other four explanatory variables,the absolute value of the normalized vegetation index(NDVI)is the highest,which can be said to dominate the spatial distribution of soil organic carbon in the Great Hinggan Mountains.