Semi natural grasslands in the Inzai city were decreased greatly by recent land use change.In this study ,we try to know what kind of method should be taken in order to preserve and conserve semi-natural grasslands in the city by revealing present condition of grassland community and conservation task.

We carried out phytosociological survey and recorded soil moisture and pH in 117 stands.Lands use type, geographical features, landscape pattern around 20m and 50m radius and presence or absence of land form types were investigated using GIS .To clarify caused factor of the community using regression tree. Dependent variable is community. Independent variable is soil pH, soil moisture, geographical features ,

The communities located in the city area were low species richness and had few native species and lacking rare species. Communities located in the place when presence of land forming were also low native species and species richness did not increase number of year after land forming.The result of regression tree high conservation value grassland is existed in slope formed or low soil pH and important factor which classifying communities is geographical features soil pH and 20 m radius landscape pattern. Considering these circumstances conserving the grassland in agricultural area and restoring grassland in city area is most effective way .