南方红壤区楠溪江流域生态健康评估

Assessment of watershed ecosystem health in red-soil region: A case study in Nanxi River

选择典型南方红壤区楠溪江流域的水域和陆域生态系统为研究对象,运用遥感和地理信息系统技术,选取包含水域的生境结构、水生生物、生态压力和陆域的生态格局、生态功能、生态压力共6类16项指标,建立流域生态健康评估体系,进行多指标综合评估与压力分析。结果表明,楠溪江流域整体健康状况良好,仅水生生物和生态功能方面状况较差,83.3%的评估单元健康状况良好,其余状况一般且均处于流域下游。流域生态系统退化主要源于流域内城镇用地面积快速增长、畜禽养殖及无序捕捞等人为干扰,建议调整流域保护区域范围,加强对点、面源污染的管控,保护水生、河岸生物多样性。该评估方法和指标体系能全面反映楠溪江流域生态健康状况,以期指导生态脆弱地带流域管理,保障该流域及下游区域水体生态健康。

In order to provide scientific supports for watershed sustainable development, operation and management,Nanxi River was selected as a typical red-soil region, and ecosystem health assessment methodology and pressure analysis combining remote sensing(RS), geographic information system(GIS) and multi-index were applied. The ecosystem health assessment was classified into two categories: water area and terrestrial area, and the indices were divided into six sections including habitat structure, aquatic organisms, ecological pressure of water area and ecological patterns, ecological function, ecological pressure of terrestrial area, which consisted of 16 sub-indicators. The results showed that the health condition of the study area was good, and only the aquatic organisms and ecological function were in ordinary condition. Among them, 83.3% of sub-basins were in good condition, while the others were in ordinary condition, and all of them were located in the downstream areas. Human disturbance was the major reason of the degradation of watershed ecosystem health, such as rapid growth of urban land areas, excessive livestock breeding and fishing. In order to improve the health conditions, more attention should be paid to adjusting the scope of the conservation areas, controlling pollution from point and nonpoint sources as well as protecting the biodiversity. The proposed assessment methodology can comprehensively indicate the health condition of Nanxi River. This case study could make a contribution to guiding the watershed management in ecologically fragile areas, and ensuring the water ecological health of the basin and its downriver.