This glossary is provided as a tool for studying
this chapter. Keep it handy while you read, in order to find definitions
of unfamiliar words, or of familiar words that may have an unfamiliar meaning
in the context of this chapter.
If
you do not find the term you are looking for on this page, try the complete
glossary.
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Arable land: Land that is capable of being cultivated and supporting
agricultural production.
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Bioaccumulation: The tendency for a pollutant to accumulate in the
tissues of plants or animals.
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Biochemical decay: Breakdown of pollutants in water through the
action of bacteria.
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Biogeochemical cycle: The movement of a particular material through
an ecosystem over long periods of time.
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Biomagnification: An increase in the concentration of a pollutant
as it is passed up the food chain, caused by a tendency for animals to
accumulate the pollutant in their tissues.
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Biomass: The total amount of living or formerly living matter in
a given area, measured as dry weight.
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Biome: A major ecological region within which plant and animal communities
are similar in general characteristics and in their relations to the physical
environment.
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Bioregion: A geographic area defined by ecological characteristics.
A bioregion includes an area of relatively homogeneous ecological characteristics,
or a specific assemblage of ecological communities. It is similar to a
biome but may refer to a smaller area with more specific characteristics.
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Biosphere resources: Resources associated with living organisms.
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Biosphere: The worldwide system within which all life functions;
composed of smaller systems including the atmosphere, hydrosphere, and
lithosphere.
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Biotic potential: The maximum rate of population growth resulting
if all females in a population breed as often as possible and all individuals
survive past their reproductive periods.
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Boreal forest: A biome dominated by coniferous forests and found
in relatively high altitudes or latitudes, almost exclusively in the Northern
Hemisphere.
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Carrying capacity: The maximum number of organisms in one species
that can be supported in a particular environmental setting.
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Chaparral: A subtropical drought-resistant and fire-prone shrubby
vegetation associated with Mediterranean-type climates.
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Community: A collection of organisms occupying a specific geographic
area.
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Cropland: Land in which crops are regularly planted and harvested.
It includes land in fallow or pasture as part of a regular rotation system.
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Desert: A biome characterized by plants and animals adapted to extreme
moisture scarcity.
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Ecology: The study of the interrelationships between living organisms
and the living and nonliving components and processes that make up their
environment.
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Ecosystem: The collection of all living organisms in a geographic
area together with all living and nonliving things they interact with.
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Ecotone: A transitional zone between two adjacent ecosystems.
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Energy efficiency: The amount of utility, either work performed
or income generated, gained per unit of an energy resource.
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Environmental resistance: Factors such as food supply, weather,
disease, and predators that keep a population below its biotic potential.
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Evapotranspiration: The process by which liquid water is conveyed
to the atmosphere as water vapor, including water use by plants.
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Feedback: An information transmission that produces a circular flow
of data in a system.
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Fertilizer: A substance added to the soil to improve plant growth.
The most commonly used fertilizers are those containing large amounts of
nitrogen, potassium, and phosphorus.
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First law of thermodynamics: The law of conservation of energy,
which states that energy is neither created nor destroyed, but merely transformed
from one state to another or converted to or from matter.
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Food chain: A linear path that food energy takes in passing from
producer to consumers to decomposers in an ecosystem.
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Food web: A complex, interlocking set of pathways that food energy
takes in passing from producer to consumers to decomposers in an ecosystem.
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Gaia hypothesis: A view of earth history that emphasizes the earth's
tendency to maintain a balance or equilibrium of natural systems.
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Grassland: A biome dominated by grasses. Most grasslands have semiarid
climates.
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Groundwater: Water below the ground surface, derived from the percolation
of rainfall and seepage from surface water.
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Infiltration capacity: The maximum rate at which a soil can absorb
water.
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Integrated pest management: A pest control technique that relies
on combinations of crop rotation, biological controls, and pesticides.
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Irrigation: The artificial application of water to a crop or pasture
beyond that supplied by direct precipitation.
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Law of entropy: The second law of thermodynamics. Entropy is a measure
of disorder in a system.
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Net primary production: The net amount of biomass created by plants
in an ecosystem once the respiration by those plants is deducted.
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Permafrost: Ground below 32ºF (0ºC) all year round.
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Pesticide: A general term used to refer to a chemical used to control
harmful organisms such as insects, fungi, rodents, worms, and bacteria.
Insecticides, fungicides, and rodenticides are kinds of pesticides.
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Photosynthesis: The formation of carbohydrates from carbon dioxide
and water, utilizing light as energy.
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Pollution: Human additions of undesirable substances to the environment.
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Potential evapotranspiration: The amount of water that could be
evaporated or transpired if it were available.
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Principle of limiting factors: Whatever factor (nutrient, water,
sunlight, etc.) is in shortest supply will limit the growth and development
of an organism or a community.
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Recycling: Reprocessing of a used product for reuse in a similar
or different form.
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Respiration: Oxidation of food that releases oxygen, water, and
energy, which are dissipated in the biosphere.
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Savanna: Tropical or subtropical semiarid grassland with scattered
trees.
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Temperate forest: A biome characterized primarily by deciduous broad-leaved
trees.
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Toxic substance: A substance that causes disease or death when organisms
are exposed to it in very low quantities.
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Trophic level: One of the steps in a food chain.
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Tropical rainforest: A biome composed primarily of evergreen broad-leaved
trees growing in tropical areas of high rainfall throughout most of the
year.
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Tundra: A biome found in arctic and subarctic regions consisting
of a dense growth of lichens, mosses, and herbs.
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Water table: The upper limit of groundwater or of the saturated
zone.
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Zoning: A system of land-use management in which land is classified
according to permitted uses.
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