Ecosystem Energetics Flashcards
What is an ecosystem?
Communities of organisms interacting with their physical environment under the influence of environmental factors
What is ecosystem energetics?
The study of how energy is fixed by autotrophs and made available to heterotrophs
How is energy measured?
By biomass (dry weight of organic matter of an organism or ecosystem)
What is the first trophic level?
Primary producers; autotrophic organisms that fix organic nutrients into organic molecules (carry out primary production)
What is the rate at which energy is fixed?
Primary productivity (usually at the ecosystem level)
- expressed as the amount of carbon fixed in a particular area at a particular time
What is gross primary production?
Total amount of energy fixed into organic molecules in an ecosystem
What is net primary production?
What the producer makes, minus what the producer keeps for itself. Measured as biomass and tells us how much energy is left for the other trophic levels
What factors affect primary productivity?
Light intensity (pleateau’s because there is more light that can be used), temperature, precipitation, nitrogen (soluble, washes away with rain, more limited on land), phosphorus (insoluble, limited in aquatic, used in DNA synthesis), CO2 (increases plat growth as long as all other nutrients are in place)
What is the second trophic level?
Primary consumers; consume organic molecules (biomass) of primary producers. Energy consumed used for energy budgets, excess will be turned into new biomass (growth)
What is biomass production called?
Secondary production
What is the third/fourth trophic level?
Secondary/tertiary consumers; consume organic molecules (biomass) of consumers in lower trophic levels
What are decomposers/detrivores?
Organisms that consume dead organic matter of primary producers, primary producers, etc…
What is energy flow lost as?
Heat
What is the first force that regulates trophic structure?
Bottom up control;
- resource abundance regulates trophic structure
- energy in each trophic level is determined by the energy in lower trophic level
What is the second force that regulates trophic structure?
Top down control;
- Predation regulates trophic structure
- Organisms in each trophic level are limited by predators in the next higher trophic level
