The "natures" of ecology¿Part I: Elaboration of the Scientific Approach in Ecosystem Ecology: Origin and evolution of the ecosystem concept; Approaches and paradigms in ecosystem ecology; Methods of studying ecosystems¿Part II: Structure and Organization of Ecosystems: The system concept and attempts to apply physical principles to ecosystem ecology; Abiotic factors and structure of ecosystems; Hierarchies, levels of organization and typology of ecological systems; Spatial and temporal scales and their consequences; Spatial heterogeneity and temporal variability¿Part III: Functioning of Ecosystems: Dynamics of communities and ecosystems: from the balance of nature to self-regulated systems; Matter and energy flows in ecosystems; Biological diversity and ecosystem functioning; The biogeochemical cycles¿Part IV: Global Ecology: Global ecology: dynamics of the biosphere; The climatic system and its variability; Biosphere-atmosphere interactions and their consequences for global equilibrium; Responses of ecosystems to climatic changes: knowing the past to understand the future.