Zoology 101 – McIntyre – Ecosystem Ecology - 7 May 2012Ecosystem: all organisms & abiotic factors with which they interactCurrencies1) Energy – organisms are key transformer (energy flow)2) Matter – organisms process material (nutrient cycling)Can view organisms in terms of…What they are made of How they get their energyHow they transfer their energy to other organismAutotroph – “self-feeding”Heterotroph – “feeding on others”Consumers: eat living organismsDecomposer: eats dead organismsEnergy transformationsPhotosynthesis CO2 + H2O – glucose + O2 (in heat)Light energy – chemical energy(Losing energy in the form of heat)Respiration Glucose + O2 – CO2 +H2O + ATPReleasing chemical energBasics of energy flowEvery energy conversion is inefficient (heat loss)Energy transfers among organisms reflectconsumptionEnergy pyramid10% rule (as you go up energy pyramid the organism only get 10% of the energy from the previous trophic level)Biomass pyramidBiomass = total weight ofparticular organisms; startwide and continue to benarrowerGlobal energy patternsNet primary production (NPP) = amount ofautotrophic material generated over time All based on 1% of solar energy reaching plants! Inefficiencies of conversion of solar energy – chemical energyLimits on energy flowAutotrophs: (limiting factors for energy: water, light,nutrients). More rainfall = more NPPHeterotrophs: (water, food) red black (high productionarea) correlates with amount of fish catches; blue (lowproduction) areas correlate with low aquatic NPPSecondary production (i.e., fish) limited by primaryproduction Biogeochemical cycles – movements & chemical transformations of biologically important elements between biotic & abiotic components of an ecosystem(s)Key elements: Carbon (C), Nitrogen (N), and Phosphorus (P) are focusThese cycles include no loses, just transfers; organism mediate many key transfersBasis of carbon cycling – energy acquisition by organisms drives cycling of key elements[SCAN IMAGE FROM WRITTEN NOTES]CO2 cycling being controlled by these organismsControls on ecosystem dynamicsTop-down control – higher trophic levelscontrolling trophic levels below itBottom-up – resources at base of food web,which control the upper trophic levelsTrophic cascades = top-down view Predators directly affect their prey; indirectly affecttheir prey’s prey. This is now the basis for“biocontrol” of algal blooms Experiment at the UW-Madison Center of Limnology Green-Lake Clear, black lakeShiner (planktivores)Zoo plankton (herbivores)Algae (autotrophs)(Algal blooms)Bass (piscivores)Shiners (planktivores)Zoo plankton (herbivores)Algae (autotrophs)Big-Picture Conclusions:1) Ecosystem research focuses on energy flow & material processing2) Energy transfers are inefficient, so energy is lost from the biota with every trophic transfer3) Matter doesn’t dissipate, but continuously cycles between biotic & abiotic formsTop-downBottom-up4) Organisms strongly affect energy flow & material cycling in ecosystemsPRE-LECTURE QUIZ1) Recycling is a key theme in ecosystem ecology. Which of the following is true? Nutrient cycling is essential for ecosystem productivity 2) Which one is the highest trophic level? a. Tertiary consumers b. Primary consumersc. Detritivoresd. Secondary consumerse. Primary consumers (Quaternary consumers are really the highest)3) What is the fate of most solar energy that reaches the Earth? Absorption, scattering and reflection by clouds and dust 4) Which factor can limit primary production by plants?a. Nitrogenb. Phosphorusc. Waterd. Lighte. All of the above5) Which taxon has the highest production efficiency? Insects 6) In an ecosystem with a typical biomass pyramid, which has the greatest biomass? Primary producers 7) Which key materials in ecosystems are currently stored primarily in rocks? Both carbon and phosphorus 8) In comparing nutrient reservoirs between tropical and temperate forests, which is not true? Nutrient cycle more rapidly in temperature forests due high rates of decomposition 9) In the Hubbard Brook region, deforestation had what effect on nutrients in the ecosystem? Strong decrease due to losses10) In restoration, which is a classic example of biological augmentation? Planting lichens to add nitrogen to the
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