高黎贡山南段河流生态系统健康评价

Health Assessment of River Ecosystem of the Southern Gaoligong Mountains

研究高黎贡山南段河流生态系统健康状况,以更好地开展生物多样性与生态系统保护工作。2018年11月,调查了高黎贡山南段6条河流22个样点的物理生境、水质和大型底栖无脊椎动物,采用河流水文指标、形态指标、河岸带指标、水质指标和大型底栖无脊椎动物指标对河流生态系统健康状况进行单因子评价,并基于多项指标构建评价体系进行综合评价。结果显示:研究区域内共采集到大型底栖无脊椎动物95个分类单元、33 725头,稀有种(单个物种数量少于338头)81种、占比85.26%,EPT指数高于5的样点19个、占比86.36%,生物多样性处于较高水平;水质状况整体较好,68.18%的样点水质为Ⅱ类水标准,其余样点水质均为Ⅲ类水标准;栖息地环境质量良好,QHEI平均得分为180.36分;综合评价结果表明研究区域内达到健康等级的样点占比为90.9%,河流生态系统整体处于健康状态,老窝河2个样点处于亚健康状态。人类活动已对少数河段的健康状况造成了影响,主要是农牧业活动、河岸河床硬化、筑坝、取水等。建议对相关河段定期开展河流健康评价,根据评价结果调整河流及河岸带的生产和开发活动,减少非必要的渠道化,针对易受干扰河段建立缓冲区,保护河流水生生物多样性。

In this study, we evaluated the river ecosystem health in the southern Gaoligong Mountains of western Yunnan, aiming to better understand the status of the aquatic ecology and biodiversity in the area and provide support for further conserving and managing the ecosystem. The study was based on field surveys and monitoring of the physical habitat, water quality and macroinvertebrates at 22 sampling sites in six rivers in the Nujiang and Dulongjiang River basins in November2018. The health status of the river ecosystem was then evaluated using single factor indices including the river hydrological index, morphological index, riparian zone index, water quality index and macroinvertebrate index, and also by using the multiple indices of a comprehensive evaluation system. A total of 33 725 benthic macroinvertebrates were collected, representing 95 species that included 81 rare species(85.26% of the total species). The EPT index exceeded 5 at 19 sites(86.36%),indicating high biodiversity. The water quality of the investigated rivers was generally good, with 68.18% of the sites meeting the Class II water standard and the remaining sites meeting the Class Ⅲ water standard. Habitat quality was good, with an average qualitative habitat evaluation index of 180.36. The comprehensive evaluation results show that the river ecosystem was in healthy state, with 90.9% of the sampling sites in a healthy level and only two sampling sites(L21 and L22 of Laowo River) in a sub-healthy state. In general, the ecological environment of rivers in the southern Gaoligong Mountains was good, but human activities have affected the health of a few river sections. Human activities affecting river health were primarily farming and animal husbandry,hardening of riverbanks and riverbeds, damming, and water removal. In view of the increasing human disturbance, we recommend regular river health evaluation of sections affected by human activities and determining river health status by both single factor assessment and comprehensive assessment. To protect the biodiversity of rivers and maintain the health of river ecosystems, the production and development activities of rivers and riparian zones should be adjusted based on evaluation results, unnecessary channelization should be reduced, and buffer zones should be established in the riparian zone of vulnerable river sections.