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Unformatted text preview: Chapter 54 1 Honors Biology Book Notes Chapter 54 Ecosystems 3/24/08- Ecosystems o Ecosystem : consists of organisms that live in an area together with abiotic environment Composed of multiple communities, along with their chemical/physical environments o Energy flow in ecosystem (1) Primary producer : an autotroph (organism which can synthesize its own food from inorganic resources), use solar energy (sometimes chemical) to manufacture food via photosynthesis Use chemical energy stored in sugars for either (1) maintenance/respiratory costs, (2) growth/reproduction o Net Primary Productivity (NPP) : when energy of primary producers invested in new tissue (2) Consumers Herbivores : (primary consumer) consumers of plants o Grazing food web : collection of organisms that eat plants, along with organisms that eat herbivores Carnivores : consumer of animals o Secondary consumers : eat herbivores or primary decomposers (bacteria, archea, fungi, earthworms, etc.) (3) Detritivores : decomposers, consumers that obtain energy by feeding on dead remains of other organisms (4) Abiotic environment : last component of ecosystem energy flow, includes soil, climate, atmosphere, matter in water, etc. o Global patterns in NPP show that terrestrial near equators has highest NPP, and oceanic zones have higher NPP near coasts, but virtually none in open ocean o Geographical NPP patterns Tropical forests cover less than 5% earths surface, account for 30% total NPP Most productive habitats in aquatic environments are marshes/estuaries/algal beds, but ocean gives more total NPP o Limits of productivity in terrestrial ecosystems Studies show that cloudcover, precipitation, and temperature all influence NPP o Limits of productivity in aquatic environments Limited mostly by lack of nutrients (iron in particular) Near-coastal regions have 2 sources of nutrients (1) Rivers that carry/deposit nutrients from terrestrial ecosystems, (2) Near-shore Chapter 54 2 oceanic currents bring nutrients back from deep ocean (deposited by dying stuff) Very few trace elements, like iron, in open ocean Fe necessary in electron transport chains, oceanic productivity probably could be increased by fertilization with iron o Experiment sprayed ocean with FeSO4 and found that amount of chlorophyll, as indicator of NPP, highest at surface of area than outside of area or 30 meters under surface inside area o Trophic level : feeding level, organisms live in same trophic level if they obtain energy from same type of source Food chain : connects trophic levels in particular ecosystem Total biomass present tends to decline from one trophic level up to...
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- Spring '08