土地利用方式下土壤有机碳特征及影响因素——以后寨河喀斯特小流域为例

为研究喀斯特小流域土壤有机碳空间分布与土地利用之间的关系,基于网格法在后寨河流域挖掘了2 755个土壤剖面,并采集了22 057个土壤样品。分析了后寨河流域不同土地利用方式下土壤有机碳密度特征。结果表明：后寨河流域土壤有机碳密度主要受人为干扰、土壤厚度与岩石裸露率的制约。不同利用方式土壤有机碳密度（0~100 cm）总体上呈现以下规律：水田>旱地>经果林地>园地>草地>弃耕地>坡耕地>乔灌木林地>乔木林地>荒地>灌木林地>灌草地。后寨河流域100 cm土壤有机碳平均碳密度为8.70 kg/m²,低于中国土壤有机碳平均密度10.83 kg/m²,总有机碳储量为5.39×10⁸ kg。科学合理地进行土地利用方式调整与管理,可以增大喀斯特小流域土壤有机碳储量。

Characteristics and Affecting Factors of Soil Organic Carbon under Land Uses: A Case Study in Houzhai River Basin

To study the relationship between the spatial distribution characteristics of soil organic carbon (SOC) and land use in karst river basins, 22 057 soil samples from 2 755 soil profiles were collected with a grid-sampling method at a 150 m scale in the Houzhai River Basin. The SOC density characteristics under different land uses were analyzed. The results indicate that human disturbance, soil thickness and rock outcrop are critical factors to SOC density in the Houzhai River Basin. The land uses in the Houzhai River Basin with SOC density (0-100 cm) in descended order are paddy lands, arid lands, artificial fruit forestlands, garden lands, grasslands, abandoned lands, sloping croplands, arbor-shrub mixed forestlands, arbor forestlands, uncultivated lands, shrub lands and shrub-grass lands. The average SOC density in the top 1 m soil of Houzhai River Basin is 8.70 kg/m² which is a little lower than the average SOC density in China (10.83 kg/m²), and the SOC storage in the Houzhai River Basin is 5.39×10⁸ kg. In conclusion, scientific and reasonable rearrangement and management of land uses could enlarge the SOC storage capacity in a karst river basin.