The coastal zone is considered as the most dynamic natural environment, providing goods and services essential to human beings. Due to diverse natural and human pressures, many coastal cities are experiencing severe environmental problems such as climate change, sea level rise, coastal erosion, environmental pollution and so on. Land use change is the apparent and widespread consequences of urbanization and global environment changes, which has important impacts on coastal zones, such as directly altering geomorphological configurations, influencing ecosystems and ecosystem services provision, and increasing coastal city's vulnerability.
The presence of a perturbation or stress, sensitivity of the affected entity and the system's capacity to cope or respond (resilience) are major elements in the vulnerability analysis of a social-economic-natural complex ecosystem. Sensitivity in this sense is defined as the interaction within the system, between the systems or inside the complex ecosystem used to characterize the response level the system according to changes in its internal or external factors. This paper presents a new approach to ecological sensitivity assessment under the vulnerability research frame, and the sustainable supply of ecosystem services is employed as a measurement of human well-being under the influence of global change threats, such as land use change.
The paper took Xiamen, a coastal city in Fujian Province, as an example to study ecological sensitivity to land use changes from the year 1987 to 2007. Firstly the ecological sensitivity mechanism of the major land use activities was analyzed, such as urban construction land expansion and reclamation. Then the Ecological Sensitivity Index (ESI) to land use change was defined as the ratio of the variation of ecosystem services value to the variation of Land Use Intensity, and the dynamic changes of ESI are calculated in detail from the year 1987 to 2007. Finally, using the layer calculation function of Geographic Information System (GIS) technology, the spatial distributions of ecological sensitivity were derivate. The results showed that construction land area increased significantly from 67.48 km² in 1987 to 308.21 km² in 2007, as much as 4.57 times. The sustained expansion of construction land came from agricultural land and forest. From the year 1987 to 2007, shoreline length of Xiamen City experienced an increase-decrease process, from 290.19 km in 1987, 343.23 km in 1992, to 299.93 km in 2007. The reclamation aimed at aquiculture causing the coastal line to zigzag and fragment, while the reclamation for transportation or construction land causing the shoreline smoother and shorter. The Land Use Intensity increased from 2.44 in 1987 to 2.52 in 2007, while the ecosystem services value showed a generally decreasing trend of 7.39×10⁹ Yuan in 1987 to 7.02×10⁹ Yuan in 2007. The mechanism research of the ecosystem sensitivity to land use change indicated that Land Use Intensity and the ecosystem services value showed an opposite trend and Land Use Intensity increased inversely with the decline of the ecosystem services value. The ESI increased from 1.50 in 1992 to 4.94 in 1997, then decreased to 4.12 in 2002, and finally increased slowly to 4.47 in 2007. Overall, in the past twenty years, the level of ecosystem affected by land use changes was not very severe. Most of the high ecological sensitivity areas located in the coastal area.