- Raymond Lindeman
• Ooze-particulate/dead organic matter
- Net Primary Productivity-plant biomass
- Gross Primary Production (GPP)-total carbon produced during photosynthesis
- Respiration (R)-some carbon used by plant cells
- Net Primary Production (NPP)-rest of carbon can be used to make biomass
- NPP=GPP-R
- First Law of Thermodynamics-Energy can be transferred or transformed, but it cannot be created or destroyed
• Quantity of energy doesn't change
- Second Law of Thermodynamics
• Quality of matter/energy deteriorate gradually over time. Usable energy is converted into unusable energy
- Energy Flow in Ecosystems
• Ecological efficiency-% energy transferred from one tropic level to the next trophic level
• avg. 10% of energy passes between trophic levels
• 3 components
- Consumption efficiency
• =amount of production consumed by next trophic level
• =consumed energy/net production energy of previous trophic level
- Assimilation efficiency
• % of ingested material that is assimilated
• depends on digestibility of food
• much plant biomass difficult to digest: Cellulose/lignin, secondary metabolites
• assimilated energy =ingested energy- egested energy
• = assimilated energy / ingested energy
- Production efficiency
• % of assimilated energy that goes to producing new biomass (Growth & reproduction)
• other assimilated energy goes to:
- Respiration-Thermoregulation, movement, blood circulation
• Production=assimilated energy-respiration
• Primary consumers-15-70% of assimilated energy used for maintenance
• Herbivores+carnivores-80-95% of assimilated energy used for maintenance
• Net production efficiency (%)
- Growth+energy in offspring/ assimilated energy
- birds <1%
- small mammals =up to 6%
- cold blooded= 75%-low maintenance-body temp.
- inversely related to activity level
- consumption energy x assimilation efficiency x net production efficiency
Assimilation efficiency increases at higher trophic levels
• higher digestibility as you go up trophic levels
Net Production efficiencies decrease at higher trophic levels
Ecological efficiencies average about 10% (5-20%)
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