喀斯特小流域土壤有机碳密度空间异质性及影响因素

论文为阐明喀斯特小流域土壤有机碳密度分布格局及其主要影响因素,运用野外布点采样、实验室测定和地统计学分析相结合的方法,采用2 755个详细调查的剖面样地,共计23 536个土壤样品,定量研究了土壤有机碳密度的空间异质性及分布特征,并利用典范分析法分析了影响土壤有机碳密度的主要环境因子。结果表明：后寨河流域各层土壤有机碳密度随土壤深度的增加而逐渐降低,最大值为12.47 kg/m²,最小值为0.11 kg/m²,100 cm土壤深度有机碳密度平均值为12.11 kg/m²,高于全国100 cm土壤深度有机碳平均密度。流域土壤有机碳密度最佳拟合模型为高斯模型,呈中等强度空间相关,Kriging插值显示土壤碳密度高值区在东部区域,低值区在南部区域,表现为中部低、四周高的趋势。后寨河100 cm深度下土壤碳密度在不同植被类型、土地利用方式、土壤类型下表现出一定差异。土壤厚度与有机碳密度呈正相关,石砾含量、坡向、坡度、土壤容重、岩石裸露率与有机碳密度呈负相关。土壤厚度、岩石裸露率、石砾含量是影响后寨河流域土壤有机碳密度的主要因子,其中以土壤厚度影响最大。

Spatial Distribution of Soil Organic Carbon Density and the Influencing Factors in a Karst Mountainous Basin

In order to illustrate the distribution pattern of soil organic carbon density (SOCD) and its main influencing factors in small karst watershed, this paper quantitatively analyzed the spatial heterogeneity and distribution characteristics of SOCD using 2 755 thoroughly investigated soil profiles consisting of 23 536 soil samples with geo-statistical analysis, and analyzed the major influencing factors of SOCD with canonical analysis. The result showed that the SOCD decreases gradually with soil depth’s increasing in the Houzhai Basin; in particular, the maximum value is 12.47 kg/m² and the minimum value is 0.11 kg/m². The average SOCD at 100 cm depth is 12.11 kg/m², which is higher than the value at national level. An optimal fitting model for the SOCD in this basin is Gaussian model, showing a moderate spatial correlation. The Kriging interpolation suggested that the soil carbon density is higher in the east region, while lower in the south region, showing an ascending trend from the middle to the surrounding area. In the Houzhai Basin, the SOCD at the depth of 100 cm differs in soil with different vegetation types, different soil utilization types and different soil types. The soil thickness is positively correlated with organic carbon content, and gravel content, slope direction, slope, soil bulk density and the rock exposed rate are negatively correlated with organic carbon density. Soil thickness, rock coverage and gravel content are the principal influencing factors of SOCD in the Houzhai Basin, among which soil thickness has the greatest impact.