An association of living organisms and their physical environment.
Ecology
The study of relationships among organisms in ecosystems.
Primary consumers
An organism that eats producers.
Secondary consumers
An organism that eats primary consumers.
Tertiary consumers
An organism that eats secondary consumers.
Ecological pyramid
A diogram that shows the biomass of organisms at each trophic level.
Biomass
A measure of the mass of organsims within a region divided by the area of that region .
Watershed
An ecosystem where all water runoff drains into a single river or stream.
Transpiration
Evaporation of water from the leaves of a plant.
Greenhouse effect
The process by which certain gases (principally water, carbon dioxide, and methane) trap heat that would otherwise escape the earth and radiate into space.