The Effect of Boundary Ridge Structures and Grass-cutting on Plant Communities Around Terraced Paddy Field

Abstract

The purpose of the study is to understand the ecological function of levees around terraced paddy fields, in terms of the habitat for grassland plants. Followings were clarified at Kashihara in Kamikatsu town, Shikoku, Japan. Wide levee has been kept incidental to paddy management, and it provides the habitat to grassland species; the ratio of levee area against paddy field area is 29.4%. Several types of plant community occur in correspond with physical conditions of the levee surface, such as humidity, whether the surface is covered by soil or rock. The difference in the frequency of grass-cutting management at the levee causes the differences in vegetation height and the degree of succession. While species richness and the diversity are not affected by management frequency. When the grass-cutting management is stopped, species richness and the diversity are kept during the following 2 years, but tend to decrease after 5 years. It seems that environmental heterogeneity of levees and continuous grass-cutting management must be maintained to sustain plant species diversity