Ecological Functions of Riparian Buffers and Effects of Pasture Development on Riparian Ecosystem

河畔緩衝帯は，日射遮断や落葉・落下昆虫・倒木の供給，細粒土砂・栄養塩の保持などの多様な機能を有する．しかし，高度経済成長期以降の大規模な農地開発に伴い河畔林が急激に消失し，河川水温の上昇や河川への土砂供給量の増加，河川・地下水水質汚染，河川生物の生息環境の悪化が問題となっている．近年，河畔林の保全や復元が強く望まれているが，河畔林の機能は十分には明らかにされておらず，具体的な施策を提案することは難しいのが現状である．そこで，本論では，国内外での研究事例を踏まえて河畔緩衝帯の機能，さらには草地開発が河畔緩衝帯・河川生態系に及ぼす影響をまとめ，今後の河畔緩衝帯の管理のあり方について検討した．Synopsis:Riparian buffers have many ecological functions, such as shading of sunlight energy, inputting of leaf liter, arthropod and large woody debris, trapping of fine sediment and nutrients. However, the riparian buffers disappeared rapidly associated with forestry activities and agricultural developments from 1960s in Hokkaido. It resulted in a rise in water temperature, sediment pollution, water pollution, and the degradation of riparian and aquatic habitat. The Japanese studies on riparian buffer are very limited, however, and the ecological functions of riparian buffers applicable to Japanese landscapes are not fully examined. Presently, concrete policies to promote conservation of riparian zone are required in watershed management. Here we reviewed the studies on ecological functions of riparian buffer with special reference to pasture development, and discussed future perspectives of riparian management