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From Individuals to Ecosystems 4th Edition - Chapter 17

Chapter 17 The Flux of Energy through Ecosystems 17.1 Introduction All biological entities require matter for their construction and energy for their activities. This is true not only for individual organisms, but also for the populations and communities that they form in nature. | Chapter 17 The Flux of Energy through Ecosystems 17.1 Introduction All biological entities require matter for their construction and energy for their activities. This is true not only for individual organisms but also for the populations and communities that they form in nature. The intrinsic importance of fluxes of energy this chapter and of matter see Chapter 18 means that community processes are particularly strongly linked with the abiotic environment. The term ecosystem is used to denote the biological community together with the abiotic environment in which it is set. Thus ecosystems normally include primary producers decomposers and detritivores a pool of dead organic matter herbivores carnivores and parasites plus the physicochemical environment that provides the living conditions and acts both as a source and a sink for energy and matter. Thus as is the case with all chapters in Part 3 of this book our treatment calls upon knowledge of individual organisms in relation to conditions and resources Part 1 together with the diverse interactions that populations have with one another Part 2 . A classic paper by Lindemann 1942 laid the foundations of a science of ecological energetics. He attempted to quantify the concept of food chains and food webs by considering the effici- ency of transfer between trophic levels - from incident radiation received by a community through its capture by green plants in photosynthesis to its subsequent use by herbivores carnivores and decomposers. Lindemann s paper was a major catalyst for the International Biological Programme IBP which with a view to human welfare aimed to understand the biological basis of productivity of areas of land fresh waters and the seas Worthington 1975 . The IBP provided the first occasion on which biologists throughout the world were challenged to work together towards a common end. More recently a further pressing issue has again galvanized the community of ecologists into action. Deforestation the