The distribution in bankside habitats of three alien invasive plants in the UK in relation to the development of control strategies

The national distribution of Fallopia japonica (Japanese Knotweed), Heracle um mantegazzianum (Giant Hogweed) and Impatiens glandulifera (Himalayan Bal sam) in bankside habitats is given for 1994-96 in the U.K. and contrasted w ith the occurrence of large stands of other nuisance plants. The typical ha bitats of these plants were derived by analysis of flow, channel and bank s ubstrates from River Habitat Surveys and shows their invasion potential acr oss the U.K. Study of the dispersal mechanisms and control techniques shows : (a) the consequences of accidental introductions to river banks from loca tions away from the river, (b) their further dispersal by the downstream dr ift of seed or fragments with their subsequent invasion, and (c) the key ar eas in the development of appropriate control programmes. The concentration of effort to immediate action and to small areas, especially upstream, is recommended, in preference to widespread but incomplete control.