Measuring the impact of urban sprawl on natural landscape pattern of the Western Taihu Lake watershed, China

Most of landscape metrics measure the connectivity of vegetation in natural landscape rather than taking the interaction between natural and urban landscape into account. The metrics of Insulation degree (ID), described by the distance of urban patches (interference patches) to the natural patch (object patch) and the area of urban patches within a specified radius of the object patch, assesses the interference effect of urban sprawl on natural landscape connectivity in Western Taihu Lake watershed, China. Using the metrics, we could easily identify the most critical natural landscape elements for the maintenance of overall connectivity such as forests, grassland and water body adjacent to cites, mountain tourist area, Yangtze River, Yao and Ge Lake. In addition, we found that urban has a fancy for sprawling along the inner edge of buffer belt and the edge of object patches, and revealed the drive forces of interference effects by the analysis of ID. Spatial differences of the metrics, in major cities areas, town areas, the area along Yangtze River and Taihu Lake and the southern and eastern mountain region, may guide the process of the Main Function Zoning project in China. Future researches should stress on spatial concepts design for urban and landscape planning in combination with the metrics. The metrics would be complemented with empirical or expert-based methods, using empirical data of local ecological dynamics.