[Spatiotemporal dynamics and landscape pattern of alien species Spartina alterniflora in Yancheng coastal wetlands of Jiangsu Province, China].

Based on the 1992-2007 remote sensing images and field survey data, and by using the landscape ecology theories and the method of conversion matrix, the spatiotemporal dynamics and landscape pattern of Spartina alterniflora in Yancheng coastal wetlands were analyzed by GIS. The results showed that the total area of S. alterniflora along the whole coastal beaches of Yancheng increased from 3561 hm2 in 1992 to 14491 hm2 in 2007, with a growth rate of 306.94%. In 1992-2007, the total area of S. alterniflora conversion-in and conversion-out was 26291 hm2 and 15361 hm2, respectively, and the S. alterniflora community in the core area of Yancheng National Nature Reserve expanded from 597 hm2 to 2814 hm2, with an annual growth rate of 24.74%. The S. alterniflora community transformed from scattered patches in estuarine regions into continuous belt pattern mainly distributed in the periphery of coastal wetlands from Sheyang River to Liangduo River. Its centroid moved to the southeast, with a distance of 2.92 km. The average area of patches increased from 1992 to 2002, and then decreased from 2002 to 2007. The largest patch index and area-weighted contiguity index increased year by year, and the shape of patches tended to be more regular.