Abstract
We analyzed factors affecting distribution patterns of alien plants around irrigation and drainage facilities in Japan using 288 flora data around the facilities and common environmental data collected at grid-cell level (30”×45”). Forest cover rate and topographic relief were negatively correlated with the rate of naturalized species and the rates of alien plants which belonged to the three life-form spectra; annual-biennial, perennial, wet species. The distribution patterns of the frequent species were considered to be strongly affected by climatic conditions such as temperature, radiation, snowfall, and precipitation rather than land use types from the fit results of the species presence-absence models to the observed occurrence patterns. These results suggest that vegetation management around an irrigation and drainage facility must be planned and conducted based on the climatic conditions and the surrounding land use type of the site.
