The dry-hot valleys and forestation in southwest China

Abstract

The dry-hot valleys (DHV) are located mainly in the deeply incised valleys along the upper streams of several international and domestically rivers, like Yangtz, Zhu, Lanchang, Hong, and Nu rivers. This paper briefly described the reasons of formation of DHV from view of climate and geographical conditions, and by referring to great deal of documents, analyzed the historical case and present status of the vegetations in DHV. The environment in DHV is facing the serious vulnerable period in the history due to its nature situation of half-year dry period, fragile geological structure and shallow soil, and its social situation, of over dense population and over farming. The primary vegetation is broad leaf forest and it was denuded in the history. The current local vegetation is the degraded secondary vegetation: savanna and succulent thorny shrub. Since, the environmental situation in valley influenced directly the water body of river, the soil erosion control and re-vegetation in DHV is the most urgent task in the process of environmental harness along the rivers. Quite a few pilot research projects have been carried out on demonstrating new silviculture techniques for re-vegetation in DHV, but there still exist great difficulties in carrying cut large-scale afforestation engineering.

Keywords

Dry-hot valley / Forestation / Environmental harness / S724 / B

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