干热河谷主要分布于长江、珠江、澜沧江、红河和怒江等国内和国际性河流的上游深切 河谷地段。本文对干热河谷形成的地理和气候原因进行了阐述，并通过引证大量文献，分析 了干热河谷植被的历史情况和现状。由于干热河谷地区的地质结构不稳定、土层浅薄、人口 膨胀、过度耕种，尤其长达半年的旱季等原因，导致该地区的生态环境处于极端的脆弱阶段 。当地的原始植被为常绿阔叶林和落叶阔叶林，但均遭到严重的破坏。现有植被为次生的稀 树草坡和肉质化刺灌木。由于干热河谷的植被情况直接影响河流水体的质量，因此河谷内的 植被恢复和水土保持就成为流域治理的最重要的任务。目前已经开展了一系列的有关造林技 术的前期研究项目，但大规模的造林培育工程尚难以开展。 Dry and hot valleys are mainly distributed in deep river valleys upstream of the domestic and international rivers such as the Yangtze River, the Pearl River, the Lancang River, the Red River and the Nu River. This article describes the geographical and climatic reasons for the formation of dry-hot valleys and analyzes the history and current status of dry-hot valleys by citing a large number of references. Due to the unstable geological structure, shallow soil layers, population expansion and over-cultivation in the dry-hot valley area, especially for six months, the ecological environment in the area is in an extremely vulnerable stage. The native vegetation is evergreen broad-leaved forest and deciduous broad-leaved forest, but both were severely damaged. The existing vegetation is a secondary savanna slope and succulent thorn shrubs. Because vegetation in dry and hot valley directly affects the quality of river water, vegetation restoration and water and soil conservation within the valley become the most important task of watershed management. At present, a series of preliminary research projects on afforestation technology have been carried out, but large-scale afforestation and nurturing projects are still difficult to carry out.