The reed marshes are diminished because of artificial activity, village civilization and concreted river bank in middle and small rivers of China, its effect of purify water quality is lost.

• 我国中小河流两岸自生的芦苇群落由于人类活动的严重干扰、农村的城市化和河岸的混凝土化,导致芦苇自然群落大面积减少,其具有的净化水质等环境保护作用在丧失。