ENV100Y5 Lecture Notes - Lecture 21: Arthur Tansley, Millennium Ecosystem Assessment, Ecosystem Ecology
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Document Summary
Ecosystem ecology: study of interactions among organisms and their physical environment as an integrated system. Sir arthur george tansley (1871-1955: " we cannot separate them [organisms] from their special environment with which they form one physical system the systems are the basic units of nature" What is an ecosystem: a way of looking at organisms and their interactions with the environment as an integrated system, focuses on functions, processes, fluxes (energy, nutrients), biogeochemical cycles, etc. Systems thinking in ecology: ecosystems are nested and hierarchical, ecosystems are dynamic, boundary between the biotic and abiotic components is often blurred. Inputs, outputs, feedback loops, resistance & resilience, emergent properties: both equally important. Inputs and outputs: closed system: matter doesn"t arrive or leave, open system: matter arrives and leaves, never truly such a thing as a closed system. Feedback loops: negative feedback (stabilizing): e. g. , density dependent, population regulation, positive feedback (destabilizing): e. g. , loss of arctic ice.
