Abstract: Landscape character assessment is a useful tool which can identify regional landscape character, prevent landscape homogenization, and promote landscape protection and development on the background of urbanization in China. According to natural elements and their spatial pattern of a landscape, this study quantitatively identified different landscape character types in Haidian District, Beijing by using a cluster analysis based on GIS and several other technologies. 46 types of thirdgrade landscape classification, 15 types of secondgrade landscape classification and 5 types of secondgrade landscape classification were identified. The spatial distribution characters of 5 firstgrade landscape types were assessed using indicators of landscape division index, patch density and landscape shape index. The results showed that there was an overlapped zone of urban landscape and rural landscape 10-12 km away from the city center. It appeared a landscape mosaic of rural landscape and pastoral landscape when the distance was beyond 12 km from the city center, while a mountain landscape was dominated when the distance was beyond 32 km. Leisurable landscape distributed separately throughout the study area.

Key words: potato, continuous monoculture, biological soil disinfestation, cultural microorganisms, Fusarium sp., soil enzyme.