第15章：生态系统 Chapter 15 Ecosystem I.Teaching Objective: Know ecosystem functions Understand ecosystem concepts and components L.Focal Points and Difficulties in the Chapter(教学重点和难点) Difficulties Ecosystem Boundaries:Ecotones Principles of Ecological Factors The Biotic Components of Ecosystems Trophic Levels Ecosystem Ecology Focal points 1.The.consists ofthe community of organisms plus the associated physical environment. 2.The study of ecosystems is included in synecology as all the organisms and environmental factorsare studied as an integrated it I.Methodology Powerpoint presentation will be the main method.Blackboard will be an assistance.Case studies will be provided. VL.Presentation(课堂讲解，学时分配为2学时左右) New tools-rapid analysis,isotopes.models.global networks Putting individualistic perspective within context of overlapping systems Increasing awareness that organisms cannot be"black-boxed" Identity of species can affect ecosystem processes Understanding huma-caused change in the earth system Energy flow and chemical cycling