漓江水陆交错带截污效果评价

Assessment of the interception effect of Lijiang River land and water ecotone

水陆交错带作为水生、陆地生态系统之间的过渡带,具有拦截水体污染物、保护河流水质等重要作用。根据立地划分原则并结合广西壮族自治区漓江风景区实际情况,将漓江水陆交错带划分为6种立地类型:薄土层河滩地、中土层河滩地、厚土层河滩地、薄土层岸坡地、中土层岸坡地、厚土层岸坡地,筛选了14个指标并建立指标评价体系,利用层次分析法将漓江水陆交错带截污效果分为4个等级:优、良、中、差。评价结果如下:在漓江水陆交错带选取了20块样地,其中,薄土层河滩地占5%、中土层河滩地占10%、厚土层河滩地占10%、薄土层岸坡地占10%、中土层岸坡地占35%、厚土层岸坡地占30%,评价为"优"、"良"、"中"、"差"的样地分别占10%、60%、25%、5%,说明漓江水陆交错带整体截污效果良好,但是有少部分区域急需修复,部分区域有潜在生态危险。根据评价结果,针对不同截污效果的漓江水陆交错带,提出最佳的生态修复措施,对漓江水陆交错带生态修复工作具有指导意义。

Lijiang River is a famous tourist scenic spot. In recent years, it faces numerous problems in the dry season in the Lijiang River land crossing zone, including serious exposure of the riverbed, large amounts of sediment in the flood period, and floating debris in the water. As a transitional zone between aquatic and terrestrial ecosystems, the land-water ecotone plays an important role in intercepting water pollutants and protecting river water quality. Here, we studied the interception effect of the land and water ecotone based on the principle of index selection and the current situation in the Lijiang River Scenic Area in the Guangxi Zhuang Autonomous Region. There are 14 indexes in the index evaluation system that are screened from three aspects： the floodplain and slope water blocking effect, the vegetation interception, and soil adsorption. Using the analytic hierarchy process （AHP） , the interception effects of the Lijiang River land and water ecotone is divided into 4 grades ： excellent, good, general, and poor. The pollution interception effects of 20 plots along both sides of Lijiang River were evaluated. The results show that 2 of the 20 plots retained complete structure. The gravel content of soil is low, the soil layer is thick, the vegetation is rich, and the pollution removal effect is obvious. Thus, their interception effect level is excellent. There were 12 plots rated ＇ good＇ with relatively complete structure. These are characterized by low gravel content in soil and a thick soil layer. Their vegetation diversity and interception effects are good. Five plots ranked at an general level. Their structure has a certain degree of damage, the soil gravel content is higher, and the soil layer is thin. The vegetation in the plot is singular and the interception effect is normal. There was one plot ranked as ＇poor＇,characterized by sparse grass species and a poor interception effect, missing land structure, and largely gravel surface. According to the evaluation results, the best ecological restoration measures are proposed for the Lijiang River land and water ecotone with different interception effects in Lijiang River, which is of guiding significance for the ecological restoration of this area. We suggest a management method to maintain the natural appearance, strengthen the construction of a monitoring system, and improve this ecotone. For the interception of good water and land ecotone, with natural recovery, the appropriate increase in human intervention. And constantly improve the interception of water and land interception function, and long-term monitoring and management. To improve the effect of interception of the ecotone, outplanting and engineering measures should be utilized, supplemented by the ecological restoration model.