Abstract
Historical change of wetland distribution was studied by GIS mapping of a 19.75×22.25 km area; about 40 km from the Tokyo metropolitan area. The sources of the GIS map were from four different periods; Rapid Survey Map made by Japanese Army in 1880's, and aerial photographs taken at the year 1945, 1974 and 1989. As the result of analysis, the total area of wetland (defined here as the open water, wetland vegetation, or the combination of the both) in the study area declined significantly during the study period. In case of the emergent plants such as reed, the total area declined whereas the number of the patches increased, which suggested the occurrence of fragmentation. In this same area, the number of the wetland bird species was surveyed both by field census and published field study data. The multiple regression analysis showed that the total area of each wetland had a strongest effect on the number of wetland bird species (r2=0.65). Other factors were the number of different wetland plant types (such as reed or cat-tail) and the shape index of each wetland. It was suggested that protecting the remaining large wetlands was the most important measure for protecting wildlife of this area.
