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Secondary Production, Energy Flows, & Ecological Efficiency
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Cedar Bog Lake, MN; Raymond Lindeman 1943, Ecology 23:157-176
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Energy flow in a Georgia salt marsh John Teal 1962 Ecology 43:639-649
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Ecological Efficiency For entire population need a bookkeeping approach, by size or age Elephant example Net Primary Prod. 747 kcal/m2/yr3125 kJ/m2/yr Food consumed 71.5 299 Fecal Energy lost 40.2 168 Maint. Metabolism 31.0 130 Growth 0.34 1.44 (0.47% of food consumed; 0.046% of NPP) Standing crop 7.1 kcal/m2 30 kJ/m2
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Ingested Energy Prey Production Detritus Not eaten ConsumptionExploitation Efficiency
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Exploitation Efficiency - Plants %total %visible Solar Radiation 100 100 Reflected 22 3.0 Evapotranspiration 38.4 \ Conduction, Convection 38.5 /94.8 Photosynthesis 1.1 2.2
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Exploitation Efficiency - Herbivores Mature Tropical Rainforest 7% Temperate Deciduous Forest 1.5-5% Desert Scrub 5.5% Temperate Grassland 1-15% 7-yr South Carolina fields12% Georgia salt marsh 8% Managed Rangeland 30-45% African Grassland - Ungulates 28-60% Open Ocean 60-99%
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Assimilated Energy Ingested Energy Prey Production Detritus Egestion Not eaten Consumption Digestion, assimilation Exploitation Efficiency Assimilation Efficiency
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Dramatic dependency on prey types. Carnivores 90% Insectivores 70-80% Granivores 80% Grazers & Browsers 30-40% Decaying wood. Millipeds15%
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Consumer Production Assimilated Energy Ingested Energy Prey Production Detritus Respiration Excretion Egestion Not eaten Death Consumption Digestion, assimilation Growth, reproduction Exploitation Efficiency Assimilation Efficiency Net Production Efficiency
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Net Production Efficiency 1. Efficiency of biosynthesis sets the upper limit Bobolink fat deposition -- 62-65% Iguana, Embryonic growth > 48% 2. Plants (NPP/GPP) Grass-Michigan, Duckweed 85 Oak-Pine, Open Ocean, Silver Spring45 Humid tropics 30
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Respiration Rates Aquatic vs Terrestrial animals (mg O2/g/hr) Aquatic Terrestrial Fish.005 -.349 Mammals 1.2 - 13.9 Insects.192 -.381 Insects.63 - 1.7 Worms.008 -.031 Birds 1.5 - 10.7 Mollusks.002 -.186
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Consumer Production Assimilated Energy Ingested Energy Prey Production Detritus Respiration Excretion Egestion Not eaten Death Consumption Digestion, assimilation Growth, reproduction Exploitation Efficiency Assimilation Efficiency Net Production Efficiency Ecological Efficiency
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Elton's Pyramids Typical values: production, biomass, numbers Production Biomass Numbers (mg/m2/day) (g/m2) (#/m2).1.1 15 1.2.66 100 26.8 1.25 1.5x10 4 280.0 17.7 7.2x10 10
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