Abstract
Native riparian plant communities are profoundly threatened by invasions of alien plants in Japan. At present, the proportion of vegetation area dominated by alien plants accounted for about 15 percent in the rivers administrated by the Ministry of Land Infrastructure and Transport. Displacement of native plant communities by invasive alien plant species is altering riparian ecosystems substantially. To preserve riparian plant communities, active management to suppress the dominance of invasive alien plants is urgently required. Weed control methods in agricultural ecosystems, which usually have strong side effects on various organisms and tend to simplify the ecosystem, are not suitable for the control measures for biodiversity conservation. Ecosystem approaches, focusing both management of invasive species and restoration of sound ecosystems simultaneously are desirable. Ecosystem management on the invasive species populations and habitat restoration should be based on sufficient information on the population ecology, and the causal factors enhancing ecosystem invasibility.
