Habitat Changes for Breeding Waterbirds in Yancheng National Nature Reserve, China: A Remote Sensing Study

Remote sensing combined with ground surveying was employed to detect the change of Suaeda glauca (common seepweed) community for the core area of Yancheng National Nature Reserve (YNNR) of China, which is a unique breeding habitat for three study species: Larus saundersi (Saunder’s gull), Tringa tetanus (common redshank), and Sterna hirundo (common tern). Landsat TM data was used to quantify the changes of the S. glauca community between 1992, 2002, and 2007. The loss of this plant community was mainly associated with reclamation for aquaculture ponds from 1992 to 2002. Using the non-dense, mosaic pixel model from Normalized Difference Vegetation Index ( NDVI ), we computed the coverage information of the S. glauca community. For each study species, the S. glauca vegetation coverage characteristics were determined from GPS locations of 407 nesting site separately. The mean vegetation coverage of nesting sites of L. saundersi , T. tetanus , and S. hirundo were 35.0 ± 6.8%, 52.2 ± 6.9% and 24.8 ± 3.6%, respectively. Over 15 years, coverage of S. glauca continuously increased due to an expansion of exotic Spartina alterniflora (smooth cord-grass) constraining early sucessional S. glauca . Eventually the S. glauca community may become too dense for nesting by L. saundersi and S. hirundo .