Abstract: Based on GIS and principal component analysis method, this paper analyzed the relationships between the patch characteristics and the plant community diversity in the patches of wetlands in Naoli River Watershed in 1950, 1967, 1983 and 2000. The results showed that in 1950〖KG-*2〗-〖KG-*7〗2000, the average patch size of the wetlands and the number of the patches that had the capacity of maintaining more than two types of wetland plant community decreased dramatically, and the minimum patch size was 101 km2. Both the plant community diversity index and the number of plant community types had significant positive correlations with the patch size of the wetlands. The larger the patch size, the higher maintenance capacity of plant community diversity. With the decrease of patch size, the patch fragmentation index and patch fragmental dimension increased, while the patch shape index and the plant community diversity index in the patches decreased. With the increase of patch spatial separation, the plant community diversity index in the patches decreased. Principal component analysis indicated that patch size was the most important factor affecting the plant community diversity of wetlands, followed by patch fragmentation and separation.

Key words: Weihe River, macrobenthos, spatial distribution characteristics, indicator species, environmental factor.