LAND-COVERED CHANGES AND ITS ECOLOGICAL EFFECTS IN THE COASTAL WETLANDS OF YANCHENG

Based on the comparative analysis of three phases Land sat remote sensing images data in 1992,2002 and 2008,and combined with field sampling investigation,the land-covered change of Yancheng coastal wetlands and its ecological effects were studied.The results shows that land-covered of coastal wetlands has occurred a significant change with the co-interference from the nature and human activities,such as the massively reduced of natural wetlands and the altered community succession of salt marsh plants resulting from the invasion of Spartina alterniflora.Spartina alterniflora invasion and the salt marsh plants change have dramatically varied the productivity of coastal wetlands.It shows a high correlation between the variation in physical-chemical properties of coastal wetlands soil and the changes of community succession and distribution patterns of salt marsh plants.Land-covered change has altered the gradient of salt marsh habitats,and has significantly influenced the emissions on greenhouse gases,chloroalkane,and reduced sulfur gas species.