论文部分内容阅读
目前,长江流域主要灾害有洪水、水土流失和泥沙淤积,其中水土流失造成地力下降,产量减低,航道缩短,水库失效。建设全流域整体防护林体系,是消除和控制这些危害的根本。它们是:一、上游高山峡谷区水源涵养林体系;二、中游水土保持林体系;三、中下游平原农田林网和护岸林体系。这些整体防护林体系建成后,长江流域的森林覆被率可达20—30％,生态系统就会实现良性循环。
At present, floods, soil erosion and sedimentation are the major calamities in the Yangtze River basin. Among them, soil erosion causes decline of soil fertility, decrease of output, shortening of waterway and failure of reservoirs. Building a whole basin-wide shelterbelt system is fundamental to eliminating and controlling these hazards. They are: First, upstream alpine gorge water conservation forest system; Second, the middle reaches of soil and water conservation forest system; Third, the middle and lower reaches of plain farmland forest network and bank protection forest system. After the overall shelter forest system is completed, the forest cover rate in the Yangtze River Basin will reach 20-30% and the ecosystem will achieve a virtuous circle.