Study On Wetland Landscape Change Driving-mechanism In Liaohe Estuary

The estuary wetlands have been heavily exploited by human for a long time due to that there are rich land, water and oil resources in these areas. In the context of the economic development with a high rate, the issue of how the landscape of typical estuary wetlands develops has attracted much attention for wetland conservation and management in our country.With multi-temporal remote sensing data and landscape pattern research approach, which is based on GIS, we analyzed the change of landscape in Liaohe estuary wetland during the last 30 years, and figured out the landscape patterns of four periods (1976,1989,1998,2004) in the study area, computed the landscape indexes and area of major landscape types, landscape type transfer matrix of 4 periods, including patch amount, type area and space transfer matrix, and finally analyzed the drive mechanism of landscape evolution in both large and small scale based on data of the societal and economic development in the local region.The results showed that:(1) Landscape types in Liaohe estuary wetland did not change during the last 30 years. Space pattern basically gives priority to large landscape patches and distributes mainly in aggregation model. And the dominated components of landscape were paddy field, reed field and mudflat. Change of landscape pattern was found mainly in the spatial transition of landscape types, and usally with rapid rate and big degree in the transiton. As a whole, the area of natural wetlands such as reed and beaches was largely lost, and the area of artificial wetlands such as padfield and pond was increased a great much. The patch amount of reed, paddyfield, land for construction, beaches and ect landscapes types decreased obviously, and the landscape diversity indexes of research area were the trend of reduced during the last 30 years.(2) The change of the landscape patterns was highly correlated with the societal and economic development of Panjin city. What this city made a advance in the societal and economic development resulted largely from wetland exploitation during the last 30 years. The main factor, influencing wetlands, was the demand for land resources caused by the rapid societal and economic development. Agricultural development resulted directly in transformation from natural and semi-natural wetlands to man-made wetlands. Oil production, road construction and urbanization not only occupied the wetlands but also change the landscape patterns and the fragmentation degree of the wetlands.(3) We take Xinxing Town of Dawa County as a sample area for drive mechanism study of small-scale landscape pattern change.We analyzed the landscape pattern change of four periods, the results showed that increase of corridor in the sample area was a result of paddy field development and oil gas exploitation, and the most obvious change in micro-landscape pattern was wetland habitat fragmentation.Our results suggest that the human activities in the recent 30 years drove the development of landscape patterns and the degradation of function in Liaohe estuary wetlands, which is significant to wetland conservation, management and sustainable development in the region.