Glossary of Terms

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The non-overlapping ranges of two or more populations of organisms (compare to sympatric).

Alluvial Fan
A wedge-shaped collection of alluvium deposited at the mouth of a ravine, stream, or river.

Sediment deposited by flowing water, as in a river, stream bed, or flood plain (plural: ALLUVIA).

Interaction in which one species is inhibited and the other is unaffected. Examples: penicillin mold accidentally inhibiting bacteria; large trees shading out smaller ones. (Compare to commensalism, competition, mutualism, neutralism, parasitism, symbiosis.)

A thin, membranous, fluid-filled sac surrounding an embryo (as inside bird or reptile eggs, or in mammals) which keeps the embryo from drying out.

Living wholly or chiefly on or in water.

Studies the interrelations of a single species to its environment.

An organism that is self-nourished, able to build organic substances from inorganic substances; a producer.

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The study of living organisms.

The total amount of living organic material in a given ecosystem; the standing crop.

Root crown.

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Meat eater; secondary consumer.

Carrying Capacity
The maximum number of a wildlife species a given habitat will support during the most critical time of the year.

A white or colorless, horny substance forming part of the hard outer covering of insects, crustaceans, and some other invertebrates.

A locality's atmospheric conditions over a long period of time. Compare to weather.

Climax Community
The final stage of a community succession.

Interaction in which one species is favored and the other is unaffected. Examples: shark and remora - the remora shares the kill but contributes little or nothing to the shark; orchids grow on, but do not affect, other trees. (Compare to amensalism, competition, mutualism, neutralism, parasitism, symbiosis.)

Interacting population of species (plant or animal) in a common location.

Interaction in which both species are inhibited. Examples: deer and elk or sheep in the same area; swifts and swallows over the same pond, feeding together. (Compare to amensalism, commensalism, mutualism, neutralism, parasitism, symbiosis.)

Dawn- and dusk-active.

Growing shoots from a root crown after a fire or other disturbance.

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Losing leaves or foliage during cold or dry periods.

Total or nearly-total loss of moisture.


Temporarily inactive.

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That branch of biological sciences that studies the interrelationships between organisms and their environments.

A natural unit of living and nonliving components which interact to form a stable system in which an interchange of materials takes place between the living and nonliving components.

A transition, or contact, zone between two or more diverse communities.

Having a variable body temperature which closely matches that of the surroundings. "Cold-blooded".

Edge Effect
The tendency for increased variety and density of organisms at community junctions (ecotones).

An organism in the early stages, before it has completed its development.

Confined to a certain region (noun form: ENDEMISM).

Having a relatively high and constant body temperature mostly independent of the surroundings. "Warm-blooded".

The physical (e.g., climate), chemical (e.g., soil), and biotic (living things) factors acting upon an organism or ecological community which determine its form and survival.

Estivation or Aestivation
Dormancy during summer or dry season.

Still in existence; living (compare to Extinct & Extirpated).

No longer living - for example, dinosaurs (compare to Extant & Extirpated).

No longer living in a particular area - for example, the grizzly bear has been extirpated from California (compare to extant & extinct).

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Food Chain and Food Web
The transfer of food energy from the source in plants through a series of organisms with repeated eating and being eaten is the Food Chain. The interlocking pattern of Food Chains makes up the Food Web.

Bundle or cluster of leaves, stem, or flowers.

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The place where an organism lives; the place where one would go to find a given organism.

Rootlike outgrowths of a parasitic plant that attach to and obtain food from a host plant. (singular: HAUSTORIUM)

Plant eater; primary consumer.

An organism that is other-nourished; obtains energy from the breakdown of complex organic substances; a consumer (see primary consumers, secondary consumers).

Dormancy during winter, generally accompanied by lower metabolic rate and temperature.

Hairy, or having hairlike parts.

Home Range
The area over which an animal generally moves in obtaining its food.

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Formed by solidification of magma.

Indicator Species
A plant or animal species, the absence or presence of which can provide information about a given area.

An animal lacking a spinal column, such as a bee, spider, lobster, or snail.

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Limiting Factors
A set of environmental requirements which each species and organism must meet for survival. These include temperature, light, water, soil condition, topography, availability of food, etc.

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Molten (liquefied by heat) rock material within the earth. When it reaches the earth's surface it is called lava.

Mediterranean Climate
A climate characterized by long, hot, dry summers and short, cool, moist, winters. Less than 3% of the entire world has this type of climate, existing in only five locations: the Mediterranean Coast, Southern California, Western Chile, the Cape of South Africa, and Southwestern Australia. All are between 30 and 45 degrees north- and south latitude.

"Wet"; habitats with plentiful rainfall and well-drained soil.

Produced by a change in form.

Interaction in which both species are favored. Examples: lichen - an alga (singular of algae) and fungus growing together; yucca and yucca moth, each dependent upon one another; ground squirrel and oak. (Compare to amensalism, commensalism, competition, neutralism, parasitism, symbiosis.)

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Interaction in which neither species is affected to a significant degree. Examples: pelicans and cormorants feeding in the ocean; spiders and mantises feeding on insects on the same bush; crows and ravens in the same cornfield; numerous songbirds feeding and nesting together in woodlands. (Compare to amensalism, commensalism, competition, mutualism, parasitism, symbiosis.)

The functional status or role an organism plays in its community.


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Animal that eats both plant and animal material (Compare to herbivore, carnivore).

Of, relating to, or derived from a living organism.

A living thing.

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Parasitism or Predation
Interaction in which one species is favored and the other is inhibited. Examples of predation: mountain lion and deer; hawk and rabbit; snake and rodent. Examples of parasitism: dodder and shrub; flea and dog; vampire and victim; creosote and other plant. (Compare to amensalism, commensalism, competition, mutualism, neutralism, symbiosis.)

Utilization of the energy of light to combine carbon dioxide and water into simple sugars.

Plant Community
A grouping of plants which have similar tolerances to a given physical environment (e.g., temperature, rainfall, soil, solar radiation, and wind). The same plant community may vary slightly in different geographical locations, but is characterized by its indicator species.

Primary Consumers
Organisms that eat plants; first-order consumers; herbivores.

Primary Succession
The process of community change on an area which has not been previously occupied by a community (such as a newly-exposed rock or sand surface.).

Largely green plants, which are able to manufacture food from simple inorganic (non-organic) substances; autotrophic organisms.

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Root Crown
Large, vegetative masses just below the soil surface found in some plants, such as Adenostoma fasciculatum, Cercocarpus betuloides, Heteromeles arbutifolia, and Malosma laurina. See stump-sprouting.

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Secondary Consumers
Organisms that eat animals; second-order consumers; carnivores.

Secondary Succession
Community development in an area from which a community was removed (such as a plowed field or cutover forest).

Formed by deposits of sediment (material deposited by water, wind, or glaciers).

The entire series of communities which develop in a given situation. A single community taken from a given period of succession is called a "seral stage".

The ability of certain plants to grow new shoots from their root crowns after being burned in a fire.

The orderly process of community change; the sequence of communities which replace one another in a given area.

The living together of two or more organisms in which the association is mutually advantageous. (Compare to amensalism, commensalism, competition, mutualism, neutralism, parasitism)

The overlapping or coinciding of geographical ranges of two or more populations of organisms (compare to allopatric) .

Study of groups of organisms as they relate to their environments.

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That portion of the home range that is actively defended.

The three-dimensional characteristics of an area, including both natural and man-made features.

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An animal possessing a spinal column, such as a mammal, bird, reptile, amphibian, or fish.

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A locality's current atmospheric conditions. Compare to climate.

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"Dry"; habitats in which plant production is limited by availability of water.