三峡库区兰陵溪流域土壤有机碳密度的影响因素

Influencing Factors of Soil Organic Carbon Density in Lanlingxi Watershed in Three Gorges Reservoir Area

研究三峡库区兰陵溪流域0~30 cm层土壤有机碳(SOC)密度的影响因素,建立该地区土壤有机碳密度的回归方程,调整碳汇策略。通过典型样点法选取该流域各土地利用方式0~30 cm土壤样品,测定其SOC密度,调查各取样点海拔、坡度、坡向、土壤理化性质等环境因子,分析SOC密度与环境因子的相关性。结果表明,该流域草地、茶园地、灌木地、林地、农地5种主要土地利用方式的平均SOC密度分别为7.55、3.83、6.04、10.24、2.83 kg/m^2,差异极显著(P<0.01);SOC密度与有机质含量(r=0.942)、黏粒含量(r=0.898)、总氮含量(r=0.863)、海拔(r=0.599)等环境因子呈极显著正相关(P<0.01);与沙粒含量(r=-0.932,P<0.01)和坡度(r=-0.407,P<0.05)呈负相关;与土壤p H、总磷含量、总钾含量的相关性不显著。SOC密度与上述环境因子的复相关系数R=0.986>0.8,为高度相关,且复相关系数大于任一自变量与因变量之间的相关系数,说明环境因子对SOC密度具有综合影响。

To reveal the influencing factors for organic carbon（SOC） density in 0-30 cm soil layer of Lanlingxi watershed in Three Gorges Reservoir area, build the regression equation for soil organic carbon density and adjust carbon sequestration strategy in this region,soil samples of top soil profile（0-30 cm） in five land-use types were selected by the typical method.The SOC densities of top soil profile（0-30 cm） and other environmental factors, such as elevation, slope and aspect and soil properties in five land-use types were investigated, and the relationships of SOC density with physical properties of soil were also examined. The results showed that the SOC density for the grassland, scrubland, forest, tea plantation and farmland on the watershed was 7.55,3.83,6.04,10.24,2.83 kg / m^2,respectively, and the difference of them reached extremely significant level（P〈0.01）. SOC density was significantly positive correlated with organic matter content（r =0.942,P〈0.01）,clay mass percentage（r=0.898,P0.01）,total nitrogen（r=0.863,P0.01）,altitude（r=0.599,P〈0.01）,and was significantly negative correlated with sand content（r =-0.932,P〈0.01） and slope（r =-0.407,P〈0.05）;the correlation between SOC density and soil pH,total phosphorus,total potassium was not obvious. Multiple correlation coefficient（R） between SOC density and environmental factors above was 0.986（R〉0.8,was highly relevant）,was greater than any one single correlation coefficient between independent variables and the dependent variable, which fully proved that environmental factors had the combined effect on SOC density.