Abstract: According to the basic theory and concept of ecosystem, the features of river ecosystem inclusive of spatial and temporal scales and habitats, hydrological processes and material fluxes, aquatic life and human activity impacts are discussed in this paper. Moreover, the environmental features and the mechanism of human activity impact in the Yangtze River ecosystem are also analysed through comparing the results of Yangtze scientific investigation with existing research findings. Research results suggest that since the Yangtze River stretches a huge area with different degrees of human activity impact, there are natural, semi-natural and human-influenced river segments. The overall quantity and quality of water meet the needs of economic and social development. However, rare and endemic species are in danger due to rapid changes of habitats and hydrological processes. More attentions should be paid to the protection and management of the ecosystem in the basin.

Key words: Yangtze River, ecosystem, continuity, rare and endemic species, habitat, human activity impact