大河岸线生态完整性内涵及评估方法——以长江岸线为例

大河岸线作为流域的重要生态空间，其内涵属性、空间格局和生态功能都具有显著的整体性。从岸线的陆域原真性、水陆生态渐变性、生境依存性及生物多样性等维度，分析了大河岸线生态完整性的科学内涵。结合国内外河流岸线生态评价研究，建立了大河岸线生态完整性的科学表征体系，提出各项指标评估和综合分级方法，并对长江岸线生态完整性进行了评估。结果表明，长江岸线生态完整性总体处于中等水平，从上游到下游沿岸各地市岸段生态完整性得分总体逐步降低；中上游地市岸段受到滨江湿地和洲岛发育程度及湿地保护状况等因素制约，下游地市岸段则受土地开发强度、自然岸线保有率、水陆连通性等制约。虽然中下游岸线有较高的开发程度且受长江大堤的约束，生态完整性受到明显影响，但在相同条件下生态完整性仍然有较大差异性，部分地区如铜陵段、安庆段和上海段仍保持了较高的完整性。大河岸线生态完整性的评估有助于形成既尊重自然规律、保护生态环境、保障防洪安全及供水安全，又能支撑社会经济发展、促进高效集约利用的长江生态岸线格局。

Implication and assessment of the ecological integrity of riverfront along great rivers: Taking the Yangtze River as an example

As the crucially ecological space in a watershed, the waterfront of great rivers shows the unified integrity in the spatial patterns, objectives and ecological functions. This paper provided an in-depth analysis of the scientific connotation of the ecological integrity of the riverfront in terms of the authenticity of shorelines, the ecological gradient on the water-land surface, habitat dependency, and biodiversity. The characterization system of the ecological integrity in great rivers'' waterfront was established based on the domestic and overseas literature, and the index system and comprehensive classification methods were proposed correspondingly. Then the ecological integrity of the Yangtze River riverfront was evaluated. The results showed that the ecological integrity of the Yangtze River riverfront was generally at an intermediate level, with the ecological integrity index of the riparian zone gradually decreasing from the upstream to the downstream. The riverfront of the cities in the middle and upper reaches was affected by the growth conditions of riverside wetlands and islands as well as the preservation of wetlands. In contrast, the riverfront of the downstream cities was constrained by the intensity of land development, the proportion of natural waterfront, and the connectivity of water and land. Although the ecological integrity of the middle and lower reaches of the riverfront has been significantly affected by the social development and the barrier of the Yangtze River dam, there was still spatial heterogeneity in ecological integrity under the same conditions, with some areas still maintaining high levels of integrity such as Tongling, Anqing and Shanghai sections. The assessment of the riverfront ecological integrity will help to promote the formation of the natural waterfront pattern of the Yangtze River that not only respects the nature, protects the ecological environment, ensures flood control and water supply safety but also supports social and economic development and efficient and intensive utilization.