Effects of Spatial Extent in Gradient Analysis of Shenyang Urban Green Space Patterns

This paper analyzes the urban landscape of Shenyang and quantifies the spatial pattern of urban green space,and investigate the effect of spatial extent in analysis of urban green space landscape pattern.We used GIS and the landscape structure analysis program FRAGSTATS,and an urban green space map based on a 2006 Quickbird image.This provides a new method to analyze urban green space by using high-resolution images,GIS,and combining gradient analysis and landscape pattern analysis.This paper analyses the five types of urban green space:green parks,green space attached to homes or businesses,road greenbelts,green space protected for production and agricultural land,along an urban gradient transect.The results of the transect analysis with landscape-level metrics showed that the spatial pattern of urban green space could be reliably quantified using landscape metrics with a gradient analysis approach.The patch density and landscape shape index showed significant gradient characteristics,while the large patch index,Shannon's diversity index,the percentage of landscape,and the landscape aggregation index were the opposite.The landscape metrics had different variation patterns when spatial extent was varied.The rate of change in space exhibits two aspects.At a small range(≤4km),the landscape index fluctuated extremely,and it cannot show a good gradient of landscape features.When the range is larger(≥5km),the landscape index changes are mild.It can eliminate interference from the high resolution and regional differences,although it also causes the loss of some gradient features.Therefore,the rate of 5km is the most appropriate scale for studying the gradient of green landscape metrics in Shenyang City.It can avoid big fluctuations in the landscape indexes,and also accurately represent the changes of the urban landscape.