Ecology 4 Dec 10 2007 - Ecosystems & Global climate...

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Unformatted text preview: Ecosystems & Global climate change I Trophic levels, food chains & food webs II Intro to ecosystem cycles III Global C cycle and rising CO 2 IV Greenhouse effect and increases in GE V Evidence for global climate change VI Consequences of climate change VII Who/what is causing this? VII What can be done? Ecosystem (definition): All of the organisms in an area, together with their physical environment Emphasis in ecosystem ecology is on the exchange of energy and materials between the living and nonliving components Ecosystem concept: biological and physical components of the environment are a single interactive system Trophic (feeding) levels form a food chain– defined by where organisms obtain their energy • Primary producers (autotrophs) obtain energy from sunlight by photosynthesis • Herbivores (eat primary producers) • Carnivores (eat herbivores or other carnivores) • Decomposers (energy comes from from chemical bonds, released by breaking down organic matter) Sometimes a food web is more accurate A boreal forest food web (Canada) Food chains represent a pyramid of energy, biomass and numbers: top carnivores are always rare Decomposition is a critical part of ecosystem function • Decomposers break down— mineralize — organic matter, making nutrients available to plants for uptake (some nutrients remain unavailable—are immobilized – by being taken up by the decomposers) • Some of the nutrients are leached , or lost, from the system into the groundwater, or in runoff • Without decomposers, we’d all be in deep doo-doo (literally) Decomposers also have food webs • Terrestrial and aquatic systems have complex decomposer food webs • Involve a wide diversity of different kinds of organisms • These include microscopic organisms, including bacteria and animals, small but visible animals and fungi, and larger organisms Some common organisms in decomposer food webs • Largest—scavenger animals (hyenas, vultures; also insects like maggots (Dipteran larvae) • Dung beetles hold a unique place of honor • Intermediate scale—earthworms, termites: consume and alter OM, decompose wood etc. • Smallest multicellular animals—nematodes, insects and arachnids Springtails (Collembola, an insect) are important decomposers in many soils and let’s not forget….....
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This note was uploaded on 04/09/2008 for the course BIOCHEMIST 361 taught by Professor Haltiwanger during the Fall '08 term at SUNY Stony Brook.

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Ecology 4 Dec 10 2007 - Ecosystems & Global climate...

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