Secondary Production, Energy Flows, & Ecological Efficiency
Cedar Bog Lake, MN; Raymond Lindeman 1943, Ecology 23:
Energy flow in a Georgia salt marsh John Teal 1962 Ecology 43:
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 Fecal Energy lost Maint. Metabolism Growth (0.47% of food consumed; 0.046% of NPP) Standing crop 7.1 kcal/m2 30 kJ/m2
Ingested Energy Prey Production Detritus Not eaten ConsumptionExploitation Efficiency
Exploitation Efficiency - Plants %total %visible Solar Radiation Reflected Evapotranspiration 38.4 \ Conduction, Convection 38.5 /94.8 Photosynthesis
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%
Assimilated Energy Ingested Energy Prey Production Detritus Egestion Not eaten Consumption Digestion, assimilation Exploitation Efficiency Assimilation Efficiency
Dramatic dependency on prey types. Carnivores 90% Insectivores 70-80% Granivores 80% Grazers & Browsers 30-40% Decaying wood. Millipeds15%
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
Net Production Efficiency 1. Efficiency of biosynthesis sets the upper limit Bobolink fat deposition % Iguana, Embryonic growth > 48% 2. Plants (NPP/GPP) Grass-Michigan, Duckweed 85 Oak-Pine, Open Ocean, Silver Spring45 Humid tropics 30
Respiration Rates Aquatic vs Terrestrial animals (mg O2/g/hr) Aquatic Terrestrial Fish Mammals Insects Insects Worms Birds Mollusks
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
Elton's Pyramids Typical values: production, biomass, numbers Production Biomass Numbers (mg/m2/day) (g/m2) (#/m2) x x10 10