喀斯特石漠化过程中土壤颗粒组成的空间分异特征

Spatial Variation of Soil Particle Composition in the Process of Karst Rocky Desertification

对喀斯特高原区贵州省清镇市王家寨峰丛洼地同一流域内不同类型石漠化、不同等级石漠化以及不同干扰方式石漠化土壤颗粒组成变化及其空间分布特征进行了研究。结果表明:随着石漠化的发展,土壤物理性粘粒(粒径<0.01mm)含量逐渐增加,物理性砂粒(粒径>0.01mm)含量逐渐减少,土壤向粘质化、紧密化发展。在不同等级石漠化中,土壤各粒级颗粒含量在中度与强度之间均无明显变化,而在轻度与强度之间除粗砂粒外均存在显著性差异(P≤0.05),轻度-中度阶段为土壤颗粒组成变化最敏感时期。黑色石灰土中的物理性粘粒普遍低于黄壤,而物理性砂粒则普遍高于黄壤,且除粗砂粒外的各粒级颗粒含量在两类土壤中均存在极显著性差异(P≤0.01)。开垦和放牧较樵采和火烧更易使土壤中的小颗粒聚集,总体表现为开垦>放牧>樵采>火烧。土壤颗粒组成受土壤有机质的影响,并影响着土壤的其他结构性能。

Karst rocky desertification is a major kind of land desertification. This article discussed the changes and spatial distribution characteristic of soil particle composition in the surficial soil of the karst rocky desertification area, including different type, different grade and different disturbed modes karst rocky desertification within the same small catchment, which belong to the Wangjiazhai peak-cluster depression basin, located in Qingzhen city, Guizhou province. The results showed that with the degree of karst rocky desertification, the soil tends to viscously and tightly, and the soil physical clay content （r〈0.01 mm） is going up while sandy content （r〉0.01 mm） is going down. There is no obvious difference on all soil particle-size between the moderate karst rocky desertification and strong karst rocky desertification, while there have significant difference between the strong karst rocky desertification and slightly karst rocky desertification （P≤ 0.05） except grit content. Slightly-moderate karst rocky desertification is the sensitive period of the changes of soil particle composition. The yellow soils have higher physical clay content and lower sandy content than that of black calcareous soil and showed the most significant difference （P≤〈0.01） except grit content. Furthermore,the small soil particles are easier to aggregation in the reclaimed and browsed rocky desertification than that of fired and lumbered rocky desertification. The rule in small particles aggregation is reclaimed 〉 browsed 〉 lumbered 〉 fired. Soil organic matter also has the effect on soil particle composition and other structural performance.