Abstract: Scale is the key issue in landscape pattern analysis, and also, in landscape ecology. Based on the land use dataset of 2002, and combining gradient analysis with landscape metrics, this paper analyzed the urban landscape of Shanghai, aimed to investigate the effects of spatial extent in analyzing urban landscape pattern. The results showed that landscape metrics had different variation patterns with the variation of spatial extent, i. e . ,varied smoothly and regularly along the land use transect when the extent was large, while fluctuated irregularly when the extent was small. The percent coverage, patch density, and landscape shape index showed significant gradient characteristics, while the largest patch index, mean patch fractal dimension, Shannon’s diversity index, and contagion were in adverse. It was suggested that a spatial extent of 5 km might be more appropriate for urban landscape pattern analysis.

Key words: Arbuscular mycorrhiza, Poncirus trifoliata, Protective system, Drought tolerance, Functional mechanism