Abstract: The floods in Yangtze valley are of long-standing and induced by many factors. Besides global and regional environmental factors, the increasing human population is one of the most important affecting factors. Since Qing Dynasty, the forest ecosystems with water-conservation capacity have been seriously destroyed, which tends to be increasingly aggravated. The facts that forest ecosystems lost their water-conservation capacity, large amounts of topsoils were run off, and the riverbeds were leveled up, were the root causes of the exceptionally serious flood in 1998. It is suggested that the role of forest as the major part of terrestrial ecosystems should be fully played, and the key work in forestry should be adjusted. The functions of forest in improving environment, preventing water and soil loss and ensuring sustainable development should be placed in first importance. Around the central task of harmonizing the development of man and nature, and in combination with the problems challenging the development of economy and the conservation of natural resources in Yangtze valley, the sustainable development of its population, resources and environment should be scientifically programmed. The information system and decision-making support system for the sustainable development should be constructed, the management of forestry should be strengthened, and the governments should secure to gradually increase the fiscal investment on forestry year by year through laws and tax revenue, truly playing the key roles of forest in environment protection, territory security and sustainable development of society and economy.

Key words: Yangtze valley, Flood disaster, Countermeasure, long-term continuous cropping, straw return, particulate organic carbon, cotton field, Fourier transform infrared