Ecological Response to Urban Expansion in An Island City:Xiamen, Southeastern China
Timely and precisely monitoring of ecological responses to urban′s fast expansion has become a very important issue for regional decision-makers. To meet this requirement, this article utilized a recently devel-oped, remote sensing based ecological index (RSEI) to assess the urban ecological quality change in Xiamen, an island city located in Fujian Province, southeastern China, during the past two decades. The RSEI was con-structed by integrating four important ecological indicators including greenness, wetness, dryness and heat.It can be represented respectively by four remote sensing indices or components, i.e., normalized difference vege-tation index (NDVI), index-based built-up index (IBI), wetness component of the tasseled cap transformation (Wet), and land surface temperature (LST). The principal component analysis (PCA) was utilized to compress the four indicators into four PC components. Instead of using a simple, traditional weighted addition algorithm, the first component (PC1) was used to construct the RSEI because the PC1 is the best one among the PC com-ponents to represent the four indicators. Time-series Landsat Thematic Mapper (TM) images of 1993 and 2009 of Xiamen scenes, both acquired in summer season, were employed to compute RSEI and evaluate the ecologi-cal quality of the island. The successful application of the RSEI in Xiamen has reveled that, in spite of a fast ur-ban expansion in the island during the study period from 1993 to 2009, the ecological quality of the island has not degraded substantially, because the RSEI value only declined slightly from 0.558 in 2003 to 0.534 in 2009. This is mainly owing to a scientific urban planning for the island city, which kept sufficient green spaces for the city and hence resulted in a much higher ratio of urban green spaces in 2009 than that in 2003. Neverthe-less, low-grade ecological conditions have also been detected by the leveled RSEI map in the newly developed northwestern part of the island city, where the Xiamen Airport is located. The area, therefore, should be im-proved for the ecological quality in the near future. The RSEI-revealed results have also been compared with those using the index generated with a simple weighted addition algorithm. The result shows that the RSEI can explain the island city′s ecological status more reasonably than the latter.
NETL
NSTL
万方数据
维普
