Ecosystems Flashcards
Ecosystem
All organisms interactions with one another and the abiotic environment. Ecosystem size boundaries:
An ecosystem may be as small as an aquarium, or a pool in a cave
Or be as large as a lake or an entire forest
Why are ecosystems important
Interactions between ecosystems and the earth-system are key for determining climate
In what terms can ecosystems all be understood
All ecosystems can be understood in terms of the transfer and transformation of ENERGY and MATTER.
Energy flows through an
Ecosystem, Cycling of matter within an
ecosystem
Lake Urmia
Algal primary producer, very short food chain (algae, artemia, wading birds)
Deep sea hydrothermal vent
Bacteria use hydrogen sulfide from vent fluids for chemosynthesis which support diverse food webs in the absence of sunlight
First law of thermodynamics
Energy cannot be destroyed or created—only transferred or transformed
How does energy enter most ecosystems
Energy enters most ecosystems as solar radiation and is transformed by photosynthesis into chemical energy which can be transferred between trophic levels and is eventually lost as heat.
Second Law of Thermodynamics
The entropy of a closed system always increases (or remains constant). Entropy = measure of disorder in a system.
Consequences of thermodynamics
Energy flows through ecosystems and cannot be cycled/recycled
Energy transfer is inefficient between trophic levels – energy is used, and some energy is always lost
Elements in ecosystems
Elements can be combined into molecules but cannot be created or transformed
Chemical elements (C, N, O, etc.) exist in the environment, can be incorporated into organisms, and can be recycled
Recycling is facilitated by detritivores & Decomposers…
- Feed on dead organic material
- Vital group of consumers active after the others have died
- Close recycling loop : without them, organic matter would pile up until
available elements are exhausted
