Characteristic analysis on the patch sizes of forest landscape in the Yiluo river catchment-A case study from Luoning County

Supported by the principle of landscape ecology and the method of geographic inform ation system ，the dynamic changes of average patch sizes and grain grade structures of forest landscapes in Luoning County，Yiluo Basin are discussed from 1984 tO 1999 and the dynamic characteristics and the trends of patch sizes are opened out．Great changes have taken place in patch sizes of landscape in the resea rch region since 1984，but the grain grade structures are mainly the small patches，and this region is tO be the landscape of fine grain structure．