中文摘要：

滇东石漠化地区裸露红土是近年来关注的一种特殊的类荒漠化景观。为了解红土裸露原因，在富源县、宣威市、罗平县等地石漠化裸露红土典型发育地段获取有植被覆盖红土及裸露红土表层样品进行有机质含量分析。结果表明，裸露红土表层有机质含量在0．06％～3．85％之间，平均值为1．31％，远低于同区域有植被生长的山原红壤样品及其它喀斯特地区土壤表层样品。石漠化过程中，植被破坏后土壤有机质大量流失，进而影响土壤结构、保水保肥能力等，导致红土裸露。滇东喀斯特地区成片分布的裸露红土应处在石漠化过程中植被退化但土壤尚未被完全侵蚀的阶段。

英文摘要：

The bare laterite is a special desert landscape discovered in east Yunnan in the recent years. In order to un- derstand the reason for the exposure of the laterite, the organic matter contents in the samples from laterites with and without vegetation cover are analyzed. The samples are collected in typical karst rocky deserts in Fuyuan, Xuanwei, Luoping counties. It turns out that the organic matter content of the bare lateritic surface-layer, averaging in 1.31 , is among 0. 06 %-3.85 0%. This value is lower than that with vegetation cover in the same area and that of oth- er kind of soil samples in southwest China karst region. In the process of rocky desertification, there is large amount of loss in the organic matter from the soil because of the vegetation deterioration. Correspondingly, the soil structure and the preserving ability of moisture and fertility are affected, which brings the exposure of the laterite. Patches of bare laterite may represent a transition stage in rocky desertification. In this stage, there is vegetation degradation and the soil hasn＇t been completely eroded yet.