Term
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Definition
A non‑living, physical factor that may influence an organism or ecosystem;
for example, temperature, sunlight, pH, salinity, precipitation. |
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Term
Biochemical Oxygen Demand (BOD) |
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Definition
A measure of the amount of dissolved oxygen required to break down the
organic material in a given volume of water through aerobic biological
activity. |
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Term
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Definition
Capable of being broken down by natural biological processes; for
example, the activities of decomposer organisms. |
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Term
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Definition
The amount of biological or living diversity per unit area. It includes the
concepts of species diversity, habitat diversity and genetic diversity. |
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Term
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Definition
The mass of organic material in organisms or ecosystems, usually per unit
area. Sometimes the term “dry weight biomass” is used where mass is
measured after the removal of water. Water is not organic material and
inorganic material is usually relatively insignificant in terms of mass. |
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Term
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Definition
A collection of ecosystems sharing similar climatic conditions; for
example, tundra, tropical rainforest, desert. |
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Term
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Definition
That part of the Earth inhabited by organisms, that is, the narrow zone (a
few kilometres in thickness) in which plants and animals exist. It extends
from the upper part of the atmosphere (where birds, insects and windblown
pollen may be found) down to the deepest part of the Earth’s crust
to which living organisms venture. |
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Term
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Definition
A living, biological factor that may influence an organism or ecosystem;
for example, predation, parasitism, disease, competition. |
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Term
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Definition
The maximum number of a species or “load” that can be sustainably
supported by a given environment. |
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Term
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Definition
A community of organisms that is more or less stable, and that is in
equilibrium with natural environmental conditions such as climate; the
end point of ecological succession. |
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Term
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Definition
A group of populations living and interacting with each other in a
common habitat. |
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Term
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Definition
A common demand by two or more organisms upon a limited supply of
a resource; for example, food, water, light, space, mates, nesting sites. It
may be intraspecific or interspecific. |
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Term
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Definition
A measure of the association between two variables. If two variables tend
to move up or down together, they are said to be positively correlated. If
they tend to move in opposite directions, they are said to be negatively
correlated. |
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Term
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Definition
The number of births per thousand individuals in a population per year. |
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Term
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Definition
The number of deaths per thousand individuals in a population per year. |
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Term
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Definition
A general model describing the changing levels of fertility and mortality
in a human population over time. It was developed with reference to
the transition experienced as developed countries (for example, those
of North America, Europe, Australasia) passed through the processes of
industrialization and urbanization. |
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Term
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Definition
A generic term for heterogeneity. The scientific meaning of diversity
becomes clear from the context in which it is used; it may refer to
heterogeneity of species or habitat, or to genetic heterogeneity. |
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Term
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Definition
The range of genetic material present in a gene pool or population of a species. |
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Term
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Definition
The range of genetic material present in a gene pool or population of a
species. |
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Term
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Definition
The range of different habitats or number of ecological niches per unit
area in an ecosystem, community or biome. Conservation of habitat
diversity usually leads to the conservation of species and genetic
diversity. |
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Term
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Definition
A numerical measure of species diversity that is derived from both the
number of species (variety) and their proportional abundance. |
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Term
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Definition
The variety of species per unit area. This includes both the number of
species present and their relative abundance. |
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Term
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Definition
The number of years it would take a population to double its size at its
current growth rate. A natural increase rate of 1% will enable a human
population to double in 70 years. Other doubling times can then be
calculated proportionately, that is, the doubling time for any human
population is equal to 70 divided by the natural increase rate. |
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Term
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Definition
The area of land and water required to support a defined human
population at a given standard of living. The measure takes account of
the area required to provide all the resources needed by the population,
and the assimilation of all wastes. (A method of calculation is provided
in 3.8.2.) |
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Term
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Definition
A community of interdependent organisms and the physical environment
they inhabit. |
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Term
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Definition
A measure of the amount of disorder, chaos or randomness in a system;
the greater the disorder, the higher the level of entropy. |
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Term
Environmental Impact Assessment (EIA) |
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Definition
A method of detailed survey required, in many countries, before a
major development. Ideally it should be independent of, but paid for
by, the developer. Such a survey should include a baseline study to
measure environmental conditions before development commences,
and to identify areas and species of conservation importance. The report
produced is known as an environmental impact statement (EIS) or
environmental management review in some countries. The monitoring
should continue for some time after the development. |
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Term
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Definition
A state of balance among the components of a system. |
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Term
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Definition
The natural or artificial enrichment of a body of water, particularly with
respect to nitrates and phosphates, that results in depletion of the oxygen
content of the water. Eutrophication is accelerated by human activities
that add detergents, sewage or agricultural fertilizers to bodies of water. |
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Term
|
Definition
The cumulative, gradual change in the genetic characteristics of successive
generations of a species or race of an organism, ultimately giving rise to
species or races different from the common ancestor. Evolution reflects
changes in the genetic composition of a population over time. |
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Term
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Definition
The return of part of the output from a system as input, so as to affect
succeeding outputs. |
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Term
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Definition
Feedback that tends to damp down, neutralize or counteract any
deviation from an equilibrium, and promotes stability. |
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Term
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Definition
Feedback that amplifies or increases change; it leads to exponential
deviation away from an equilibrium. |
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Term
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Definition
In the context of human populations, this refers to the potential for
reproduction exhibited in a population. It may be measured as fertility
rate, which is the number of births per thousand women of child‑bearing
age. Alternatively it may be measured as total fertility, which is simply the
average number of children a woman has in her lifetime. |
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Term
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Definition
The Gaia hypothesis (developed by James Lovelock and named after the
ancient Greek Earth goddess) compares the Earth to a living organism in
which feedback mechanisms maintain equilibrium. |
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Term
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Definition
An increase in average temperature of the Earth’s atmosphere. |
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Term
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Definition
Gross National Product, the current value of all goods and services
produced in a country per year. |
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Term
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Definition
Those atmospheric gases which absorb infrared radiation, causing world
temperatures to be warmer than they would otherwise be. This process is
sometimes known as “radiation trapping”. The natural greenhouse effect
is caused mainly by water and carbon dioxide. Human activities have led
to an increase in the levels of carbon dioxide, methane and nitrous oxide
(dinitrogen oxide, N2O) in the atmosphere, and there are fears that this
may lead to global warming. |
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Term
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Definition
The environment in which a species normally lives. |
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Term
Halogenated Organic Gases |
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Definition
Usually known as halocarbons and first identified as depleting the ozone
layer in the stratosphere. Now known to be potent greenhouse gases.
The most well known are chlorofluorocarbons (CFCs). |
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Term
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Definition
The process by which two populations become separated by
geographical, behavioural, genetic or reproductive factors. If gene flow
between the two subpopulations is prevented, new species may evolve.
See evolution. |
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Term
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Definition
Species that usually concentrate their reproductive investment in a small
number of offspring, thus increasing their survival rate and adapting
them for living in long‑term climax communities. |
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Term
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Definition
The angular distance from the equator (that is, north or south of it) as
measured from the centre of the Earth (usually in degrees). |
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Term
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Definition
Less economically developed country: a country with low to moderate
industrialization and low to moderate average GNP per capita. |
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Term
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Definition
More economically developed country: a highly industrialized country
with high average GNP per capita. |
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Term
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Definition
A simplified description designed to show the structure or workings of an
object, system or concept. |
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Term
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Definition
A relationship between individuals of two or more species in which all
benefit and none suffer. (The term symbiosis will not be used.) |
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Term
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Definition
A term sometimes used by economists for natural resources that, if
appropriately managed, can produce a “natural income” of goods and
services. The natural capital of a forest might provide a continuing natural
income of timber, game, water and recreation. |
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Term
Non - Renewable Natural Capital |
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Definition
Natural resources that cannot be replenished within a timescale of the
same order as that at which they are taken from the environment and
used; for example, fossil fuels. |
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Term
Renewable Natural Capital |
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Definition
Natural resources that have a sustainable yield or harvest equal to or less
than their natural productivity; for example, food crops, timber. |
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Term
Replenishable Natural Capital |
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Definition
Non‑living natural resources that depend on the energy of the Sun for
their replenishment; for example, groundwater. |
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Term
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Definition
The form in which human population growth rates are usually expressed:
(crude birth rate - crude death rate)/10
Inward and Outward migration is ignored |
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Term
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Definition
A species’ share of a habitat and the resources in it. An organism’s ecological
niche depends not only on where it lives but also on what it does. |
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Term
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Definition
A relationship between two species in which one species (the parasite)
lives in or on another (the host), gaining all or much (in the case of a
partial parasite) of its food from it. |
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Term
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Definition
The movement of the eight major and several minor internally rigid plates
of the Earth’s lithosphere in relation to each other and to the partially
mobile asthenosphere below. |
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Term
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Definition
The addition to an environment of a substance or an agent (such as heat)
by human activity, at a rate greater than that at which it can be rendered
harmless by the environment, and which has an appreciable effect on the
organisms within it. |
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Term
Non - Point Source Pollution |
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Definition
The release of pollutants from numerous, widely dispersed origins; for
example, gases from the exhaust systems of vehicles. |
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Term
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Definition
The release of pollutants from a single, clearly identifiable site; for
example, a factory chimney or the waste disposal pipe of a factory into
a river. |
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Term
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Definition
A group of organisms of the same species living in the same area at the
same time, and which are capable of interbreeding. |
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Term
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Definition
The total gain in energy or biomass per unit area per unit time, which
could be through photosynthesis in primary producers or absorption in
consumers. |
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Term
Gross Primary Productivity (GPP) |
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Definition
The total gain in energy or biomass per unit area per unit time fixed by
photosynthesis in green plants. |
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Term
Gross Secondary Productivity (GSP) |
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Definition
The total gain by consumers in energy or biomass per unit area per unit
time through absorption. |
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Term
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Definition
The gain in energy or biomass per unit area per unit time remaining after
allowing for respiratory losses (R). Other metabolic losses may take place,
but these may be ignored when calculating and defining net productivity
for the purpose of this course. |
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Term
Net Primary Productivity (NPP) |
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Definition
The gain by producers in energy or biomass per unit area per unit time
remaining after allowing for respiratory losses (R). This is potentially
available to consumers in an ecosystem. |
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Term
Net Secondary Productivity (NSP) |
|
Definition
The gain by consumers in energy or biomass per unit area per unit time
remaining after allowing for respiratory losses (R). |
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Term
|
Definition
The gain by producers in energy or biomass per unit area per unit time.
This term could refer to either gross or net primary productivity. |
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Term
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Definition
The biomass gained by heterotrophic organisms, through feeding and
absorption, measured in units of mass or energy per unit area per unit
time. |
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Term
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Definition
Species that tend to spread their reproductive investment among a
large number of offspring so that they are well adapted to colonize new
habitats rapidly and make opportunistic use of short-lived resources. |
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Term
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Definition
The set of communities that succeed one another over the course of
succession at a given location. |
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Term
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Definition
The term now used for any haziness in the atmosphere caused by
air pollutants. Photochemical smog is produced through the effect of
ultraviolet light on the products of internal combustion engines. It may
contain ozone and is damaging to the human respiratory system and
eyes. |
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Term
|
Definition
An arbitrary group of individuals who share some common characteristic
such as geographical location, cultural background, historical timeframe,
religious perspective, value system, and so on. |
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Term
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Definition
A mixture of mineral particles and organic material that covers the land,
and in which terrestrial plants grow. |
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Term
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Definition
A vertical section through a soil, from the surface down to the parent
material, revealing the soil layers or horizons. |
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Term
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Definition
The process through which new species form. See also evolution. |
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Term
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Definition
A group of organisms that interbreed and produce fertile offspring. |
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Term
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Definition
The condition of a system in which there is a tendency for it to return to a
previous equilibrium condition following disturbance. |
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Term
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Definition
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Term
Steady - State Equilibrium |
|
Definition
The condition of an open system in which there are no changes over the
longer term, but in which there may be oscillations in the very short term.
There are continuing inputs and outputs of matter and energy, but the
system as a whole remains in a more or less constant state (for example, a
climax ecosystem). |
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Term
|
Definition
The orderly process of change over time in a community. Changes in
the community of organisms frequently cause changes in the physical
environment that allow another community to become established and
replace the former through competition. Often, but not inevitably, the
later communities in such a sequence or sere are more complex than those
that appear earlier. |
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Term
|
Definition
Use of global resources at a rate that allows natural regeneration and
minimizes damage to the environment. For example, a system of
harvesting renewable resources at a rate that will be replaced by natural
growth might be considered to demonstrate sustainability. |
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Term
|
Definition
An assemblage of parts and the relationships between them, which
together constitute an entity or whole. |
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Term
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Definition
A system in which energy, but not matter, is exchanged with its
surroundings. |
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Term
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Definition
A system that exchanges neither mat ter nor energy with it s
surroundings. |
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Term
|
Definition
A system in which both matter and energy are exchanged with its
surroundings (for example, natural ecosystems). |
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Term
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Definition
The position that an organism occupies in a food chain, or a group of
organisms in a community that occupy the same position in food chains. |
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Term
|
Definition
The arrangement or patterning of plant communities or ecosystems into
parallel or sub‑parallel bands in response to change, over a distance, in
some environmental factor. The main biomes display zonation in relation
to latitude and climate. Plant communities may also display zonation with
altitude on a mountain, or around the edge of a pond in relation to soil
moisture. |
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