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UW-Milwaukee BIOSCI 150 - Ecosystems

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Outline of Last LectureOutline of Current LectureEcosystemsNet Primary ProductivityBiogeochemical CycleThe Global Carbon CycleThe Greenhouse EffectGlobal WarmingEffects on AnimalsMain Current ProblemsReviewBIO SCI 150 1st Edition Lecture 22Outline of Last Lecture 1. Ecology Stabilitya. Successionb. Species Diversityi. Diversity ImportanceOutline of Current Lecture 1. Ecosystemsa. Net Primary Productivityb. Biogeochemical Cyclei. Global Carbon Cycleii. The Greenhouse Effectiii. Global Warming1. Effects on Animals2. Main Current ProblemsKey TermsEcosystems - All the organisms in a community and their abiotic environmentBiomes – A broad type of terrestrial ecosystemFood chain – Feeding relationships between trophic levelsNet Primary Productivity - energy invested in new tissue by autotrophsEvapotranspiration – a measure of temperature and water availabilityBiogeochemical Cycle – The path an element takes as it moves from abiotic systemsthrough living organisms and back againEcosystemsAll the organisms in a community and their abiotic environmentEnergy flows and nutrient cycles link the biotic and abiotic environments.Biomes: A broad type of terrestrial ecosystem- Biomes related to: PRECIPITATION & TEMPERATUREEcosystems have four components that are linked bythe flow of energy:Food chain: Feeding relationships between trophic levels Each feeding level within an ecosystem represents a trophic level (in order below)…- Heterotrophso Secondary consumer (carnivore)o Primary consumer (herbivore)- Autotropho Primary producer Food chains are short because of loss of energy at each trophic levelEnergy lost at each level because:1. Not everything eaten & digested (waste)2. Energy is used for maintenanceNet Primary ProductivityNet Primary Productivity - energy invested in new tissue by autotrophsWhat limits Net Primary Productivity?- Evapotranspiration: a measure of temperature and water availability- Nitrogen & Phosphorus are often limiting in Aquatic environmentsThe most productive biomes are warm and wet:- Tropical rainforests, reefs and marshesBiogeochemical CycleBiogeochemical Cycle – The path an element takes as it moves from abiotic systems through living organisms and back again- Bio-magnification of persistent chemicals- The overall rate of nutrient movement is limited most by decomposition of detritus.o Boreal forest: Accumulation ofdetritus and organic mattero Tropical wet forest: Almost noorganic accumulationThe Global Carbon CycleOceans have the most Carbon (CO2)Humans release 7.9 gt/yr => 3.4 gt/yr ends up in atmosphereThe Greenhouse EffectSvante Arrhenius - Nobel Prize in ChemistryCO2 reflects infrared radiation back to Earth => retaining heat- ~50% of sun’s energy (short-wave) absorbed at surface- infrared (long-wave) radiation emitted to atmosphere- Worldwide avg temp 15C; -17C without greenhouse effect!- 2x CO2 => 1.6 C warmingGlobal WarmingGlobal climate change due to both natural and anthropogenic causes- Overall the climate has increased since the `20s- Since 1979, more than 20% of the Polar Ice Cap has melted awayEffects on Animals- 1/3 of frog species threatened worldwideo 74 of 110 species of harlequin frogs in Latin America have gone extinct in last 20 years - 20 of 65 (31%) of bird species breeding earlier in the United KingdomMain Current Problems"Solving the climate problem for the next 50 years with current technologies"Main Current Problems:- Atmosphere is 78% N2, but biologically inactive- Soil bacteria: N2 => Ammonium (NH4) => Nitrate (NO3) => Plants and animalsReview- Four components of Ecosystems: o Primary producers (Autotrophs)o Consumers &Detritivores (Heterotrophs)o Abiotic environment (chemical and physical- Each feeding level within an ecosystem represents a trophic levelo At each trophic level most energy is lost (90%)o Biogeochemical cycles: The path an element takes as it moves from abiotic systems through living organisms and back again.o Overall rate of nutrient movement is limited most by decomposition ofdetritus.LECTURE QUESTION The 2007 IPCC report indicates that:- Global climate change is causing low oxygen “dead zones” in the oceans off Louisiana and India- Global climate change is due to natural causes such as sunspot activity and recent volcanic eruptions- Global climate change is due to a combination of natural and anthropogenic (human) causes- Global change is primarily due to CO2 releases from


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