Key Terms
Ecosystem
Living community plus its abiotic environment. Equilibrium: stable state where organisms and environment are balanced.
Equilibrium
The steady state where all organisms are in balance with their environment and each other.
Food chain
Linear sequence showing how energy and nutrients pass through an ecosystem.
Food web
A holistic, nonlinear model showing all feeding relationships across trophic levels.
Three ways
1. Photosynthesis (photoautotrophs): plants, algae, photosynthetic bacteria; use sunlight 2.
Biomass
Total mass of living organisms in a trophic level at a given time. GPP: total energy captured by primary producers.
Gross primary productivity (GPP)
Total rate at which primary producers capture energy from the sun.
Net primary productivity (NPP)
Energy remaining after producers use some for respiration and heat loss. NPP = GPP minus respiration and heat loss
TESTABLE DETAIL (Silver Springs)
GPP = 20,810 kcal/m2/yr. After respiration/heat loss of 13,187, NPP = 7,633 kcal/m2/yr available to primary consumers.
Trophic Level Transfer Efficiency (TLTE)
TLTE = (production at trophic level N) divided by (production at trophic level N-1), times 100
Net Production Efficiency (NPE)
How efficiently a trophic level converts food it receives into biomass.
Example
Caterpillar NPE = 18%; squirrel NPE = 1.6%
Biomagnification
Increasing concentration of persistent, toxic substances in organisms at each successive trophic level.
How it works
Toxins accumulate in tissue and are not broken down; each predator concentrates all the toxins from everything it ate.
Six key elements in organic molecules
Carbon, nitrogen, hydrogen, oxygen, phosphorus, sulfur.