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), Heracleum mantegazzianum (Giant Hogweed) and Impatiens glandulifera (Himalayan Balsam) in bankside habitats is given for 1994-96 in the U.K. and contrasted with the occurrence of large stands of other nuisance plants. The typical habitats of these plants were derived by analysis of flow, channel and bank substrates from River Habitat Surveys and shows their invasion potential across the U.K. Study of the dispersal mechanisms and control techniques shows: (a) the consequences of accidental introductions to river banks from locations away from the river, (b) their further dispersal by the downstream drift of seed or fragments with their subsequent invasion, and (c) the key areas 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.