Abstract: The ecosystem delineation on ecosystem services is an important baseline framework for resource and environmental management pursued by China in recently years. In this paper, the authors first discussed the nature of delineation, and then pointed out that the delineation is an ecosystembased geographical identification, with a focus especially on ecosystem viability influenced by human activities and integrated human values. Through the delineation, we need not only to answer where an ecosystem is and what it provides, but also answer how people value its provision and how human values affect the sustainability of an ecosystem. The ecosystem delineation on ecosystem services, based on the nested hierarchy organization of the ecosystem and its multiscale characters, aims at multiscale ecosystem management. As a case study, watershedbased delineation of ecosystems on priority ecosystem services in the upper Yangtze River is developed and presented. It is concluded that the main task comprises of delineating ecosystem units and services, assessing ecosystem integrity, and naming the dominated ecosystem function. Finally, the ecosystem management recommendations in the upper Yangtze River are given under the new framework.

Key words: watershed, ecosystem delineation on ecosystem services, ecosystem integrity, dominant ecosystem service, ecosystem management