近30年苏北滨海滩涂湿地演变特征与空间格局

苏北滨海滩涂湿地位于现代长江口与废黄河口之间,是最典型的淤泥质平原海岸,其演变特征及空间格局具有鲜明的特征。本文选用1980年、1992年、2008年的TM 和ALOS影像为主要数据源,构建了基于空间分割和转移矩阵分析模型,研究了近30年来苏北滨海滩涂湿地的演变特征及其空间格局。结果表明： ①苏北滨海滩涂发生了巨大变化,近30年间滩涂总面积减少了1273.11 km²,平均每年减少45.47 km²;滩涂湿地侵蚀/淤积面积约965.14 km²,0 m等深线冲刷后退减少的面积约为307.97 km²。②苏北滨海滩涂湿地区域差异性明显。南北方向上可划分为6个自然地理单元,东西方向上可划分为3个区域。③苏北滨海滩涂湿地演变中,湿地转型、湿地丧失和湿地演替分别占总面积的38.39%、14.80%、20.51%;其中天然湿地减少354.1 km²,人工湿地增加1061.45 km²,非湿地增加253.09 km²。④滩涂湿地主要植被群落演替特征和空间分布也呈现出差异性。湿地演替主要发生在净变区,与对应岸段的海岸侵蚀/淤积类型基本吻合。

Evolution and spatial patterns of tidal wetland in North Jiangsu Province in the past 30 Years

Coastal wetlands and tidal land in North Jiangsu Province are the most typical mudflat in China, which lies between the estuaries of the Yangtze River and the former Yellow River channel. This article examines the evolution and spatial distribution of wetlands and tidal land in North Jiangsu Province between 1980 and 2008 through image analysis of Landsat TM images from 1980 and 1992 and ALOS images from 2008. The results indicate that: (a) The study region had experienced enormous changes in this time period. The total area of coastal wetlands decreased by 1273.11 km², that is, at an annual rate of 45.47 km²; the erosion-sedimentation area was 965.14 km² and the erosion area was about 307.97 km². (b)This region can be divide into six geographic units from the north to the south, and three zones from the east to the west (overlay unit, changed unit, and mudflat unit); (c) In these natural units, the proportion of transformed wetlands was 38.39%, while the proportion of lost wetlands was 14.97%. Natural wetlands decreased by 354.1 km², constructed wetlands increased by 1061.45 km², and non-wetland area increased by 253.09 km². Changed units were about 20.51% of the total area, in which most wetlands are in natural successions. (d) The study area also had distinct regional succession characteristics and distribution patterns of vegetation communities. Natural wetlands succession occurred mainly in the changed units with a total area of 554.52 km², which is in agreement with the erosion/sedimentation situations of corresponding section.