西南喀斯特地区典型林分土壤优先流特征及影响因素

研究喀斯特地区的优先流现象,明确影响优先流的主要因素,对当地植被恢复具有重要意义。通过野外染色示踪试验以及图像处理技术,获得染色溶液在垂直和水平方向上的分布情况,并提取总染色面积比、基质流深度、优先流比和长度指数作为优先流特征参数,运用灰色关联度分析法对影响优先流的14个因子进行分析。结果表明: 喀斯特地区典型林分土壤存在优先流现象,其优先流主要有漏斗状和树枝状两类,有横向水流运动现象发生。喀斯特地区林下的染色面积比平均为19.4%,基质流深度、优先流比和长度指数平均分别为4.96 cm、62.9%和385.5%。在影响优先流的14个环境因子中,对染色面积比影响最大的是土壤初始含水量,对基质流深度影响最大的是速效钾含量,对优先流比和长度指数影响最大的均为速效磷含量。喀斯特地区典型林分下优先流的发育程度高且空间变化剧烈,土壤初始含水量等物理性质对其有较大影响,土壤养分也是优先流的一个重要影响因素。

Characteristics and influencing factors of soil preferential flow in typical stands of Karst area in southwest China

The study of preferential flow phenomena in Karst areas and the identification of the main factors influencing preferential flow are of great importance for the recovery of local vegetation. The distribution of the dyeing solution in the vertical and horizontal directions was examined by field staining tracer test and image processing technique. We analyzed the total dyeing area ratio, matrix flow depth, preferential flow ratio, and length index as pre-ferential flow characteristic parameters, and 14 factors affecting preferential flow using grey correlation analysis. The results showed that there were two main types of preferential flow, funnel-shaped and dendritic, with lateral water movement occurring in the soil of typical Karst stands. The mean value of the dyeing area ratio of the understory in Karst areas was 19.4%, and that of the matrix flow depth, preferential flow ratio, and length index was 4.96 cm, 62.9%, and 385.5%, respectively. Among the 14 environmental factors influencing preferential flow, the initial soil moisture content had the strongest influence on the dyeing area ratio, the available potassium content had the most significant influence on the matrix flow depth, and available phosphorous content had the most significant influence on both the preferential flow ratio and the length index. The high degree of development and spatial variability of preferential flow under typical forest stands in Karst areas was strongly influenced by physical properties such as initial soil water content, while soil nutrient also exerts important influence on preferential flow.