长江干流典型区域河流生境健康评价

河流生境是河流生态系统中的重要组成部分，是维持河流健康的重要因素。河流生境健康的准确评估可以为河流生态系统的保护与修复提供重要依据。针对长江干流生境特点，从河流物理生境形态、河流岸边带生境和水环境特征3个方面选取了10个指标，构建了长江干流生境评价的指标体系。基于该评价体系，在2017年8~9月对长江干流的金沙江下游、三峡库区、长江中下游3个典型区域的127个调查断面进行河流生境综合评估。结果表明：金沙江下游、三峡库区、长江中下游河流生境综合指数（RHI）分值的分别为133.9、124.6、130.8，总体评价等级均为“良”。水流情势、受人类活动干扰是金沙江下游生境变化的主要驱动因子，河岸渠化硬化、河岸植被覆盖、河岸植被带宽则是三峡库区和长江中下游生境变化的主要驱动因子。建议长江上游区域强化水生生物重要栖息地完整性保护，中下游区域加强岸边带、洲滩的生态修复，恢复江湖连通性，构建长江流域生态廊道和生物多样性保护网络。

Health Assessment of River Habitat in Typical Regions of the Yangtze River Mainstream

River habitat is an important component of river ecosystems which play an important role in maintaining river health. River habitats assessment can provide an important basis for the protection and restoration of degraded river ecosystems. We established an evaluation system which is specific to the characteristics of the mainstream in the Yangtze River, with ten indexes from three aspects of the river physical morphology, riparian zone habitat and water environmental characteristics. Based on the evaluation system, comprehensive assessment of river habitats was carried out from August to September 2017 in 127 survey sections of three regions, which are the lower reaches of the Jinsha river, the Three Gorges Reservoir, and the middle and the lower reaches of the Yangtze river. The evaluation results show that the river habitat comprehensive index (RHI) of the three regions are 133.9, 124.6 and 130.8, respectively, which were all at the “good” level. The river hydrology and disturbance by human activities are the main driving factors affecting the habitat quality of the lower reaches of the Jinsha River. The river canalization and hardening degree, riparian vegetation cover and riparian vegetation bandwidth are the main driving factors affecting the habitat quality of the Three Gorges Reservoir and the middle and lower reaches of the Yangtze River. In the next step, we should continue to protect the integrity of aquatic habitats in the upper reaches, to carry out restoration of the riparian, the bottomland and the connectivity of rivers and lakes in the middle and lower reaches, as to build an ecological corridor and biodiversity conservation network of the Yangtze River.