喀斯特小流域土壤有机碳分布特征及其影响因素

为阐明喀斯特小流域土壤有机碳含量分布格局及其主要影响因素,采用野外布点采样、实验室测定相结合的方法,利用后寨河流域2755个详细调查的剖面信息,定量研究了土壤有机碳含量的分布特征,并利用主成分分析法分析了影响后寨河流域土壤有机碳含量的主要因子。结果表明,流域内土壤有机碳含量高、变异性强。流域表层土壤有机碳平均含量为25.07g/kg,变幅为1.61~119.11g/kg。全流域整个剖面土壤有机碳平均含量为20.71g/kg,土壤有机碳含量变异系数变幅为52.68%~75.28%,呈中等强度变异;流域土壤有机碳含量处于较高的水平,91.7%的样点表层土壤有机碳含量高于11.6g/kg;石砾含量与土壤有机碳含量性关系不显著,土壤有机碳含量与坡度、海拔、岩石裸露率均呈极显著正相关关系,与容重呈显著负相关关系;主成分分析结果表明,海拔、坡度、土壤类型是影响后寨河流域土壤有机碳分布的主导因子,在土壤有机碳储量估算时必须高度重视。

Distribution Characteristics of Soil Organic Carbon and Its Influencing Factors in a Small Watershed of Karst Region

To illustrate the soil organic carbon content(SOCC) distribution pattern and primary influencing factors of SOCC in a karst watershed, this research studied the SOCC distribution pattern in Houzhai River Basin on the basis of detailed information of 2 755 soil profiles from field investigation and laboratory analyses. Primary influencing factors affecting SOCC distribution were analyzed too, using the principal component analysis(PCA).Results show that soil organic carbon in Houzhai River Watershed has high contents and variability. The average SOCC in topsoil is 25.07 g/kg, ranging from 1.61 g/kg to 119.11 g/kg. The average content of soil organic carbon in the whole basin is 20.71 g/kg with the coefficient of variation of each soil layer from 52.68% to 75.28%, showing a moderate transformation with a high variability. SOCC in this watershed stays at a high level, and 91.7% of the SOCC in surface soil samples are greater than 11.6 g/kg. The relation between SOCC and the content of gravel is not significant. However, the SOCC is significantly positive correlated with slope, elevation and the rate of exposed rock, and significantly and negatively correlated with the unit weight. The PCA indicated that slope, elevation and soil type are major factors that influenced the distribution of SOCC in the Houzhai River Watershed. Great attentions should be paid on these items in calculation of soil organic carbon storage.