The Research On Spatial Distribution Of Soil Organic Carbon And Its Correlation With Soil Properties In Different Forest Types Of Mixed Broadleaf-conifer Korean Pine Forest

Mixed broadleaf-conifer forest is the important forest type of northeast forest ecosystem in China, also an important part of forest ecosystem in China, the distribution of soil organic carbon and the correlation between soil nutrients has important significance to our country forest ecosystem carbon assessment.By means of setting sample plots respectively in the four forest types of Ulmus japonica mixed forest, Acer mandshuricum mixed forest, Carpinus cordata mixed forest, Acer mono mixed forest in secondary mixed broadleaf-conifer forest in Jiaohe of Jilin province, the forests stand structure were investigated and collected the sampled soil samples, the soil organic carbon and nutrient reserves were determined, in order to analyze its vertical distribution characteristics, using traditional statistical method, in order to compare the influence of different forest types on soil organic carbon accumulation and the correlation of soil nutrients and organic carbon, using the method of statistical methods and ordinary kriging interpolation method, in order to do the interpolation prediction for the soil organic carbon density of the sample area, and draw the space distribution map. The conclusion is as follows:1) The soil organic carbon density of the study area is 16.09 kg · m-2,the soil organic carbon content and carbon density in the four kinds of forest types decreased with increasing soil depth, the soil organic carbon in first layer has the highest proportion, it has significant difference between the three kinds of soil layers, also has obvious characteristics of vertical distribution. Soil pH value has not significant difference between the three soil layers (p<0.05), except soil total potassium, there were significant differences between 0-10cm,10-20cm and 20-30cm soil layer of the soil nutrients.2) The soil organic carbon density of the forest soils in the study area is Carpinus cordata(18.21 kg · m-2)>Ulmusjaponica(16.16kg · m-2)>Acer mandshuricum(15.75 kg · m-2)>Acer mono(14.23 kg · m-2). Variance analysis showed that there were significant differences between the four kinds of forest (p<0.05), Carpinus cordata mixed forests were the highest in each soil layer. The variation rule of the four types of forest soil organic carbon content and density follow Ulmus japonica> Acer mandshuricum> Carpinus cordata> Acer mono. In various nutrients of soil, total nitrogen, total potassium, available nitrogen, effective phosphorus and available potassium had significant differences between the four forest types (p<0.05), Carpinus cordata mixed forest also is highest, except the soil phosphorus, its difference between Carpinus cordata and Ulmus japonica mixed forest is not significant, secondly, there were only significant different between Acer mandshuricum and Acer mono mixed forest for the soil rapidly-available potassium.3) By analyzing the correlation relationship between soil organic carbon and soil nutrients separately for each soil layer and four forest types found that, except total potassium in soil, the relationship between soil organic carbon content or density and the indexes of the different soil characteristic reached extremely significant or significant correlation, among them, the correlation coefficient of total nitrogen is the largest.Among the soil nutrients, total phosphorus related significantly to soil organic carbon in Carpinus cordata and Ulmus japonica mixed forests, rapidly-available potassium only associated with the soil organic carbon in Carpinus cordata mixed forests, the correlation relationship between soil total nitrogen or alkaline hydrolysis nitrogen and the soil organic carbon of four kinds of forests were significantly. Correlation analysis results showed that the soil organic of the four types of forest is closely related to soil nutrient status. Applying stepwise multiple regression to establish two regression equations about soil organic carbon content, total nitrogen, total phosphorus and soil organic carbon density, total nitrogen, the density of soil, their regression relationships are very significant, among them, the soil organic carbon of two types of elm forest were showed significant correlation with total nitrogen and total phosphorus, so in the elm forest, soil total nitrogen, total phosphorus, which can be taken as reference to the forest soil organic carbon density indicative index.4) Using statistical methods to analyze the spatial heterogeneity of soil organic carbon density showed that 0 to 10cm and 0 to 30cm soil layer soil organic carbon density are since has strong spatial correlation, respectively fitting out the semi-variogram model is index model and spherical model. The spatial distribution features were estimated by ordinary kriging interpolation method, and drawing the study area spatial distribution map about the soil organic carbon density of two types of soil layer, the distribution map showed that organic carbon density of high value area is more focused on the south of the study area, and distributed on the edge of the forest and the border region.