Abstract:
Three TM images obtained on 7 June 1992,26 May 2002 and 20 May 2006 respectively were interpreted as basic information sources.The landscape pattern change of Yancheng coastal wetland in recent 15 years was analyzed.In 1992,there was an area of 80 918 ha for natural wetlands,including bare beach covered 31 604 ha,taking up 28.32% of total area of coastal wetlands;22.65% Phragmites australis wetland,and 1.04% Imperata cylindrica wetland.As for artificial wetlands,the area of fish pools was 16 138 ha,which is 14.46% of total area of coastal wetlands;the farmland area was 10 293 ha;and the area of salt wetland was 3.82% of total area of coastal wetlands.In 2002,there was an area of 40 227 ha for natural wetlands,including Spartina wetland covered 13 989 ha,taking up 12.53% of total area of coastal wetlands;8.48% Suaeda salsa wetland and 0.92% Imperata cylindrica wetland.As for artificial wetlands,the area of fish pools was 48 264 ha,43.24% of total area of coastal wetlands;the farmland area was 18 540 ha;and the area of salt wetland was 4.11% of total area of coastal wetlands.In 2006,there was an area of 30 278 ha for natural wetland,including Phragmites australis wetland covered 9 217 ha,occupying 8.26% of total area of coastal wetlands;7.74% Spartina wetland and 0.77% Imperata cylindrica wetland.As for artificial wetlands,the area of fish pools was 53 717 ha,48.13% of total area of coastal wetlands;the farmland area was 23 041 ha;and 4.11% salt wetland.There was a significant drop on the area of natural wetland and a rapid rise on the area of artificial wetland from 1992 to 2006.The area of bare beach shrank mostly in the patches,decreasing 28 515 ha during 15 years.The areas of Phragmites australis wetland and Suaeda salsa wetland showed the same trend.The reclamation resulted in area of natural wetland decrease and area of artificial wetlands increase.About 37 579 ha fish-pool and 12 748 ha farmland had been reclaimed during 15 years.Wetland landscape change occurred in the transformation,from bare beach to fish-pool and Spartina wetland,from Phragmites australis wetland to fish-pool in the period of 1992-2002;and from Spartina wetland to fish-pool,from fish-pool to farmland,from Suaeda salsa wetland to Phragmites australis wetland in the period of 2002-2006.Wetland landscape change occurred in the following areas,Sheyang Estuary-Xinyang Port,Doulong Port-Chuandong Port and Chuanshui Port-Laoba Port from 1992 to 2006.In Sheyang Estuary-Xinyang Port,7 971.75 ha Phragmites australis wetland and Suaeda salsa wetland had been explored to fish-pools.In Doulong Port-Chuandong Port,12 687.93 ha bare beach to fish-pools,in Chuanshui Port-Laoba Port,5 400.18 ha Phragmites australis wetland to farmland.