摘要

It is generally accepted that biodiversity will be better protected from anthropogenic disturbances after a region has been designated as a protected area. However, this common perception is not true in the case of the Yancheng Biosphere Reserve (YBR), which is widely regarded as the largest wintering habitat in the world for red-crowned cranes. Combining previous information with multisource remote sensing data, this study constructed a highly accurate habitat suitability index (HSI) model and produced a series of HSI hierarchical maps to fill in the blanks of long-term monitoring and regular data acquisition in the YBR. Based on the integrated methods of geographic information system analysis, landscape indices, and redundancy analysis, this study characterized the entire process of shrinkage and deterioration of the habitats of red-crowned cranes and revealed the underlying driving forces. The results can be summarized as follows: (1) The total area of suitable and secondary suitable habitats decreased significantly, from 43.3 to 24.6%, during 1991-2013, and suitable habitats became increasingly concentrated in the core zone. (2) The ecological quality of the habitats was significantly degraded, as reflected by increasing fragmentation, isolation, and scattering of suitable and secondary suitable habitats, as well as by expansion and aggregation of marginal suitable and unsuitable habitats. (3) The extensive transformation of the original natural wetlands to aquafarms is the main reason for habitat shrinkage, with construction of buildings and overall increased intensity of human activity being significantly responsible for the ecological deterioration.