Analysis on Spatial -Temporal Landscape Pattern and Ecological Security in Zhangjiagang City Using 3S Technologies and CA Model

In order to certain the landscape pattern and ecological security in Zhangjiagang, the landscape characteristics of urbanization phase and suburbanization phase were analyzed, using remotely sensed imageries between 1991-2006, land use maps and GIS technology, combined with urban-suburban-rural gradient research. Based on the landscape changing and its driving force analysis, the regional Cultivated Land Instability Degree (CLID) of 2004 was defined and calculated. The ecological security of Zhangjiagang between 2003-2007 was also assessed to research the impacts of urbanization on urban ecological security. The urbanization process in Zhangjiagang matched the cyclic model and the diffusion wave theory and for casted the future land use/cover using CA Model. The effects of urbanization appeared in urban areas firstly, and then in rural areas. Two kinds of urban expansion patterns were detected in Zhangjiagang. The first one was from edge-expansion to infilling growth, the second one was from edge-expansion to spontaneous growth, and then to edge-expansion. Among all the agricultural ecological deficit, the largest proportion was the grassland ecological deficit, and agricultural ecological deficit increased by 16.22% from 2003 to 2007. This study had proved that the agricultural development was not sustainable in Zhangjiagang in recent years.