城市化背景下近30年武汉市湿地的景观变化

Landscape changes of Wuhan wetlands in 1978-2007 with the process of urbanization

以1978—2007年6期LandsatTM(MSS)影像为基础数据,分析了城市化背景下武汉市湿地景观近30年的动态变化规律。结果表明:武汉市湿地景观面积逐年减少,平均年减小量为1655.79hm2,年下降率为0.89%,其中1991—2002年湿地景观的年变化率高于武汉市湿地景观近30年间的年平均变化率,与建成区面积变化相对应;研究期内武汉市自然湿地面积减少,人工湿地面积略有增加;湖泊湿地是武汉市湿地景观的主要类型,其面积下降速度最快,是武汉市湿地景观面积减少的直接因素,人工湿地面积的增加并未改变武汉市湿地面积减少的趋势;快速城市化使武汉市湿地景观表现出斑块密度和景观破碎度逐渐增大、分维数逐渐减小、连通性降低的趋势。虽然保护性法律法规的实施遏制了湿地萎缩的速度,但并未改变湿地面积下降的趋势,因此,应进一步加强武汉市湿地保护与规划,并着重开展河流和湖泊湿地的保护。

By using the multi-temporal Landsat TM （or MSS） images in 1978-2007 as the basic data, this paper analyzed the landscape changes of Wuhan wetlands under the background of urbanization in recent 30 years. In the study period, the wetland area in Wuhan was decreasing, with a mean annual decreasing rate of 0. 89% and a mean annual decrement of 1655.79 hm2. In 1991-2002, the annual decreasing rate of wetland landscape was higher than the mean decreasing rate in recent 30 years, and was synchronous with the area increase of Wuhan buih-up area. During the study period, the area of natural wetland decreased, while that of constructed wetland increased. As a major type of Wuhan wetland, the lake wetland had the fastest decline in area, being a direct cause of wetland area decrease in Wuhan. The increasing area of constructed wetland did not change the decreasing trend of total wetland lands in Wuhan showed the trends of patch density and area. With rapid urbanization, the wetfragmentation increased and fractal and connectivity decreased. Though the implementation of related protection laws kept the rate of wetland shrinking within limits, the decreasing trend of wetland area in Wuhan did not have any change. Therefore, the protection and planning of Wuhan wetlands, especially the river and lake wetlands should be further strengthened.