基于景观开发强度法的湿地健康变化研究

基于景观开发强度法（LDI方法），对黄旗海湿地生态系统健康受人类干扰程度进行评价。以黄旗海湖区及其缓冲区（100～600 m）为研究对象，根据Landsat MSS、TM、ETM影像解译得到1976年、1987年、1993年、1999年、2006年、2010年的土地利用分类，计算不同土地利用类型（耕地、草地、裸地、湿地）的景观开发强度系数（LDI系数），并加权计算各年总体LDI值。结果表明，湿地内部各土地利用类型LDI系数均呈现增加趋势，其中湿地增幅最大（77%）。空间LDI系数分布由湖区内部向边缘逐渐增加。湿地LDI值总体呈现增加的趋势，而生态系统健康呈下降趋势。1976—1993年黄旗海湿地及其缓冲区处于“健康”状态，1993—1999年生态系统由“健康”向“一般”过渡，1999—2010年彻底转变为“一般”。湖区不合理的农田耕作、草地放牧以及非点源污染是造成LDI值逐年上升的主要原因。建议加强保护区建设，有效禁止湖区内部放牧及耕作，设立湖岸带缓冲区以减少农田非点源污染。

Assessment of the Changes of Wetland Health Based on Landscape Development Intensity Index

In this paper, a landscape development intensity (LDI) approach was used to assess the ecosystem health of Huangqihai wetland. Huangqihai Lake and its buffer zones (100～600 m) was taken as the study area, and the land use classifications were extracted from the image interpretation of Landsat MSS, TM, and ETM. Then the landscape development intensity coefficient of different land use types (cropland, grassland, bare land, wetland) were calculated for 1976, 1987, 1993, 1999, 2006, and 2010, as well as the overall weighted LDI index value. The results showed that the LDI coefficients of all types of land use had an upward trend, in which wetland had the largest increasing rate (77%). The spatial distribution of the landscape development intensity coefficient gradually increased from the inner part of the lake to the edge of the lake. The LDI index of the Huangqihai lake and its buffer zones had an upward trend generally, making the ecosystem health aggravating. The study areas were in the state of health from 1976 to 1993, followed by the period of transition from ‘health’ to ‘sub-health’ during 1993—1999, and completely transformed into ‘sub-health’ from 1999 to 2010. The improper farming and grazing, as well as the agricultural non-point source pollution were the main reasons for the increase of LDI index. Therefore, we suggested that the enforcement of regulation should be improved in the protected area, grazing and farming should be banned in the lake, the lakeshore buffer reducing the non-point source pollution should be set up.