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Yancheng National Nature Reserve (YNNR) in Jiangsu province is the largest wintering habitat for red-crowned cranes (Grus japonensis) in the world. However, the Spartina alterniflora (S. alterniflora) expansion had caused a series of ecological problems. In the paper, by using ETM + images as data source, GIS technology and the InVEST model were used to analyze the influence of S. alterniflora expansion on the landscape pattern and habitat quality through scenario simulation. We found that: from 2000 to 2020, under the current conditions, the percentage of landscape (PLAND) of S. alterniflora marsh would increase from 17.525% to 51.522%, which would result in a risk of extinction for the Suaeda salsa (S. salsa) marsh; the habitat quality index (Q) would be decreased from 0.8183 to 0.7074. Under the condition of removing S. alterniflora, the PLAND of S. salsa marsh would be restored to 43.8317%, and the Q would be increased to 0.9463. Under the condition of controlling S. alterniflora expansion, the PLAND of S. alterniflora marsh would be decreased to 8.678%, the PLAND of S. salsa marsh would be restored to 43.8653%, and the Q would be increased to 0.9198. The results would be beneficial to the management of the YNNR. [ABSTRACT FROM AUTHOR]

Taking the core area of Jiangsu Yancheng Wetland National Nature Reserve as a case, spatial and temporal changes of habitat quality were analyzed from the viewpoint of Red-crowned crane (Grus japonensis (Statius Müller, 1776)), and other rare birds. The results showed that the area of mudflats and Suaeda salsa marshes decreased, the area of Spartina alterniflora marshes, Phragmites australis marshes, aquaculture ponds and roads increased during 1983 to 2011. The value of habitat degradation index increased from 0.006 to 0.024 during 1983 to 2011, which meant the habitat degradation was becoming more serious. The spatial distribution of habitat degradation had been a distinct longitudinal band from an obvious lateral belt. The value of habitat quality index decreased from 0.863 in 1983 to 0.742 in 2011, which meant the habitat quality became worse due to the expansion of aquaculture ponds and Spartina alterniflora. Based on 1983, the value of habitat scarcity index increased from -0.10 to 0.173 during 1997 to 2011, indicating that the ecosystem function was declining. The values of habitat scarcity index of Suaeda salsa marsh and mudflat were obviously rising and were also the highest which were 0.628 and 0.637 in 2011, respectively. It indicated that Suaeda salsa marsh and mudflat became more and more scarce. They needed more protection and restoration. [ABSTRACT FROM AUTHOR]