<正>依据林业发达国家———日本对森林水文、森林生态效益评价等方面的研究成果，论述了森林对防洪减灾、水源涵养、土壤保持所发挥的重要作用及其机制；简要介绍了日本多年来规划、实施森林治山治水的重点建设项目，借鉴其成功经验，提出了建设江河流域保安林的必要性。

According to the research achievements of forest hydrology and the valuation of forest ecological benefits in Japan with an abundance of forest, the important effects and machanism of forest functions on preventing flood and decreasing calamities, conserving water and soil were dealt with. The key construction projects of managing mountains and water with forest which were planed and practiced in Japan for several years were introduced briefly. Drawing on the successful experience of other countries, the necessity of the construction of protecting forest on river system was put forward.