流溪河流域土地利用景观生态安全动态分析

在GIS技术支持下，基于景观干扰指数和景观脆弱度指数构建景观生态安全评价指标体系，分析流溪河流域2000年、2005年和2009年3相土地利用景观生态安全变化。景观生态安全指数定量化地表征了流域景观生态安全状况，结果表明：（1）流域景观生态安全格局受城市化及人类活动干扰显著增强，林草地和耕地面积减少，园地面积增加，10年间各景观类型的破碎度、分离度总体呈现增加趋势，且流域内优势景观类型发生改变，2000年和2005年以林草地和耕地为优势景观，而2009年优势景观转变为林草地和园地；（2）2000-2005年，流域过半景观生态安全格局发生了变化；2005-2009年期间流域景观生态安全转移率约为60%，约有90%的流域景观生态安全格局在空间分布上发生了变化；（3）2000年整个流域景观生态安全指数都大于0.6，其中大于0.8的面积占99.99%；2005年，生态安全度大于0.6的面积比例为98.48%，景观生态安全指数大于0.8的面积较2000年降低55.93%；景观生态安全度大于0.6的区域2009年比2005年减少了72.93%，主要分布于流域上游；整个流域范围内没有生态安全指数大于0.8的区域分布，流域景观生态安全度呈现整体降低趋势。

Dynamic Trend of Land Use Landscape Ecological Security in Liuxihe Watershed

Supported by GIS and based on landscape disturbance index and landscape fragility index, a comprehensive evaluation index system for landscape ecological security is constructed, the change of land use landscape ecological security in the Liuxihe watershed in 2000, 2005 and 2009 is analyzed. The results show that: 1) The influence of human activities on watershed landscape ecological security pattern was significantly enhanced, forest and cultivated land decreased, while construction land and orchard land increased, leading to the increase of fragmentation and isolation of each landscape type，and the dominant landscape types were changed from forest-grass land plus cultivated land to forest-grass land plus orchard. 2) From 2000 to 2005, more than half of the patterns of landscape ecological security changed, and from 2005 to 2009, the transfer rate of watershed landscape ecological security was about 60%, and 90% of the spatial patterns of landscape ecological security of the watershed changed; 3) In 2000 all the landscape ecological security indexes (ESk) of the watershed were more than 0.6. In 2005 the areas with indexes of 0.6 or higher (ESk ≥0.6) accounted for 98.48% of the total, and the areas with ESk ≥0.8 decreased by 55.93%, as compared with those in 2000. In 2009, the areas of ESk ≥0.6 reduced by 72.93%, as compared with those in 2005, which were mainly distributed in the upstream of the basin. Now there is no area with ESk ≥0.8 in all of the watershed. Its landscape ecological security is decreasing.