喀斯特小流域土壤石砾分布特征及其影响因素

为探究喀斯特土壤石砾含量的影响因素、形成机制及其分布规律，采集了3 180个土壤样品，分析后寨河流域不同影响因素下土壤石砾含量的分布规律，并利用相关性分析得出了影响后寨河流域土壤石砾含量的主要影响因子。结果表明，坡度、岩性、土层厚度和植被类型是影响土壤石砾含量分布的主要影响因素，其中坡度对喀斯特地区土壤石砾含量的分布特征影响作用最大。在不同坡度条件下，土壤石砾含量的分布规律为:坡度<30°时随坡度增加，土壤石砾含量增大。坡度>30°时随坡度增加，土壤石砾含量减小。不同土层厚度下，土壤石砾含量分布规律为:随土层厚度增加，土壤中石砾含量减少。植被类型不同，土壤石砾含量大小排序为:灌木>草本>乔木。不同岩性发育形成土壤，土壤石砾含量大小排序为:白云岩>石灰岩>泥灰岩>第四纪黄粘土>砂页岩。喀斯特地区岩性决定风化成土速率和土壤石砾总量，是土壤石砾含量的物质来源基础。坡度是促进土壤石砾含量迁移、再分配的驱动因素，植被类型和土层厚度是影响土壤石砾含量的响应因素。 

Characteristics of soil gravel distribution in karst small watershed and its influencing factors

In order to explore the influencing factors, formation mechanism and distribution of karst soil gravel content, 3,180 soil samples were collected to analyze the distribution features of soil gravel contents influenced by different factors in the Houzhai river basin; and the method of correlation analysis was employed to determine the primary influencing factors. The results show that the slope, lithology, soil thickness and vegetation type are the main factors influencing the soil gravel contents, among which the slope has the greatest influence on the soil gravel content distribution in karst areas. Under the condition of different slopes, the changes of the soil gravel content are as follows: When slope < 30 °, soil gravel content increases with the slope. When the slope > 30 ° soil gravel content decrease with the slope. The results also show that soil gravel content decreases with the increase of soil thickness. The order of soil gravel content in different vegetation types is: shrub > herb > tree. Different lithologies can form soils, in which the order of soil gravel content is: dolomite > limestone > argillaceous limestone > quaternary yellow clay > sand shale. The lithology of karst area has a great impact on the weathering rate and gravel volume of the soil, which is the material source of soil gravel content. The slope is the driving factor to promote migration and redistribution of soil gravel content, while vegetation types and soil-bed thickness are the response factors.