heterotroph

(het-ur-oh-trohf) [Gk. heteros, other, different + trophos, feeder]
An organism that obtains organic food molecules by eating other organisms or their by-products.

chemosynthetic

Applied to autotrophic bacteria that use the energy released by specific inorganic reactions to power their life processes, including the synthesis of organic molecules.

photosynthesis

[Gk. photos, light + syn, together + tithenai, to place]
The conversion of light energy to chemical energy that is stored in glucose or other organic compounds; occurs in plants, algae, and certain prokaryotes.

producer, in ecological systems

An autotrophic organism, usually a photosynthesizer, that contributes to the net primary productivity of a community.

autotroph

(aw-toh-trohf) [Gk. autos, self + trophos, feeder]
An organism that obtains organic food molecules without eating other organisms. Autotrophs use energy from the sun or from the oxidation of inorganic substances to make organic molecules from inorganic ones.

primary productivity

The rate at which light energy or inorganic chemical energy is converted to the chemical energy of organic compounds by autotrophs in an ecosystem.

denitrification

The process by which certain bacteria living in poorly aerated soils break down nitrates, using the oxygen for their own respiration and releasing nitrogen back into the atmosphere.

nitrogen fixation

The assimilation of atmospheric nitrogen by certain prokaryotes into nitrogenous compounds that can be directly used by plants.

transpiration

[L. trans, across + spirare, to breathe]
The evaporative loss of water from a plant.

evaporative cooling

The property of a liquid whereby the surface becomes cooler during evaporation, owing to a loss of highly kinetic molecules to the gaseous state.

biogeochemical cycles

[Gk. bios, life + geo, earth + chemeia, alchemy; kyklos, circle, wheel]
The various nutrient circuits, which involve both biotic and abiotic components of ecosystems.

secondary succession

A type of succession that occurs where an existing community has been severely cleared by some disturbance.

primary succession

A type of ecological succession that occurs in an area where there were originally no organisms.

ecological succession

Transition in the species composition of a biological community, often following ecological disturbance of the community; the establishment of a biological community in an area virtually barren of life.

parasitism

commensalism

mutualism

mutualism

competitive exclusion principle

The concept that when the populations of two species compete for the same limited resources, one population will use the resources more efficiently and have a reproductive advantage that will eventually lead to the elimination of the other population.

resource partitioning

The division of environmental resources by coexisting species populations such that the niche of each species differs by one or more significant factors from the niches of all coexisting species populations.

niche

The sum total of an organism's utilization of the biotic and abiotic resources of its environment.

habitat

[L. habitare, to live in]
The place in which individuals of a particular species can usually be found.

abiotic

[Gk. a, not, without + bios, life]
Nonliving; specifically, the nonliving components of an ecosystem, such as temperature, humidity, the mineral content of the soil, etc.

biotic

(by-ot-ik) [Gk. bios, life]
Pertaining to the living organisms in the environment.

taiga

(ty-guh)
The coniferous or boreal forest biome, characterized by considerable snow, harsh winters, short summers, and evergreen trees.

conifer