TERMINOLOGY OF ECOLOGY
Species: A species is a natural biological
unit tied together by the sharing of a
common gene pool. It can be also defined
as a uniform interbreeding population
spread over time and space.
Vegetation: The collective and continuous
growth of plants in space is called
vegetation. Thus, vegetation is actually the
totality of plant growth, including large or
small populations of each species
intermixed in a region. In other words we
may say that vegetation is the sum total of
plant population covering a region.
Flora: Flora is the species content of the
region irrespective of the numerical strength
of each species.
Population: A population is a group of
individual organisms of the same species
in a given area.
Community: A community is a group of
population of different species in a givenarea. It thus includes all the populations in
that area- all plants, all animals and
microorganisms.
Factor: Any external force, substance or
condition that affects organisms in any
way, is known as factor.
Environment: The sum of all factors
constitute environment. It thus becomes
indeed a complex of so many factors, better
referred to as environmental complex.
Habitat: The place, where an organism
lives, or the place where one would go to
find the particular organism is known as
the habitat of that organism. The habitat
of an organism actually represents a
particular set of environmental conditions
suitable for its successful growth.
Adaptation: Any species puts its efforts to
make full use of the available nutrient pool
and other environmental conditions
prevailing in the area of its growth. It
ensures its own protection against adverse
conditions of the habitat. This all is
accomplished by the development of some
characteristics.
ECAD: Some of the species have more than
one kind of populations spread over wide
range of habitat conditions. An ecad of a
plant species is a population of individuals
which although belong to the same genetic
stock, but differ markedly in vegetative
characters such as size, shape, number of
leaves, stems, etc. These variations are
simply environmentally induced, and thus
are temporary or reversible i.e. one type of
ecad may change into another with the
change in its habitat.
Ecotype: An ecotype is a population of
individuals of a species, which are
genetically different. Since different
ecotypes are inter-fertile, these are kept
under the same taxonomic species. Their
variations are permanent and irreversible
as these are genetically fixed.
Eco-tone: Although plant species grow in
association with each other in groups as
communities in nature, there is hardly
distinguishable a point or sharp line of
distinction between the two different
communities. There is generally a zone of
transition, presenting a situation of special
ecological interest between two different
types of communities, which is known as
an eco-tone.
Life Form: A life form is the sum of the
adaptation of the plant to the climate. This
view point is considered in the
physiognomic method of study of plant
communities.
Biological Spectrum: The percentage
distribution of species among the various
life forms of a flora is called the biological
spectrum of that place.
Ecological Succession: Vegetation is hardly
stable, and thus dynamic, changing over
time and space. Although comparatively
less evident than vegetation, animal
populations, particularly lower forms, also
show dynamic character to some extent.
Succession is a natural process by which
different groups or communities colonize
the same area over a period of time in a
definite sequence. The succession, which
starts from a primitive substratum without
any previous living matter, is known as the
primary succession, whereas that starting
from the previously built up substratum
where living matter already existed, is
known as the secondary succession. If the
existing community, as a result of its
reaction with the environment, causes its
own replacement, then such a succession
is known as autogenic succession but if the
replacement of the existing community
takes place due to the influence of any
external force or condition, then it is called
allogenic succession.
Climax: In the natural process of
succession, one community continues to
follow another, until a stage comes when a
type of community cannot be displaced
under the prevailing environmental
conditions. This final, terminal community,
that can maintain itself more or less
indefinitely in equilibrium with the
prevailing environment, is known as the
climax community and the stage is said to
be the climax.
Biome: A complex of several types of
communities, some in climax stage and
others in different stages of succession,
maintained more or less similar climatic
conditions is known as a biome.
Ecosystem: In a given area, the biotic assemblage of all the organisms, plant as
well as animal communities, interacts with
its physical environment in such a manner
that there is a flow of energy leading to
clearly defined trophic structure, biotic
diversity and material cycles within a
system, is known as an ecological system
or ecosystem. An ecosystem is the whole
biotic community in a given area plus its
abiotic environment.
Biosphere: The earth’s living organisms
interacting with their physical environment
may be considered as a giant ecosystem,
which is the largest and most nearly selfsufficient
biological system we know, and
this is designated as the biosphere or
ecosphere. Thus the planet earth along with
the atmosphere, hydrosphere and
lithosphere which sustain life is known as
biosphere.
Standing State: The amount of inorganic
substances, such as P, S, C, N, H etc. present
at any given time in the environment of an
ecosystem, is known as the standing state
or standing quality.
Standing Crop: The amount of living
material, present in a component
population at any time, is known as the
standing crop, which may be expressed in
terms of numbers or weight per unit area.
Biomass: Biomass is the standing crop
expressed in terms of weight (i.e. organism
mass) of the living matter present.
Food Chain: In any ecosystem, various living
organisms are arranged in a definite sequence
according to their food habits. Plants are
producers which are eaten by herbivores,
which in turn are eaten by carnivores. This
transfer of food energy from the source in
plants through a series of organisms with
repeated eating and being eaten is known as
a food chain in an ecosystem.
Food Web: Under natural conditions in the
same ecosystem, depending upon the
variety of organisms, there generally
operate a number of linear food chains at
a time. These chains are interlinked with
each other at several points. This
interlocking pattern of a number of food
chains forms a web-like arrangement
known as food-web.
Productivity: The rate of production i.e.
amount of organic matter accumulated in
the living component of an ecosystem in
unit time is referred to as the productivity
of the ecosystem. Primary Productivity is
defined as the rate at which radiant energy
of sun is stored by photosynthetic and
chemosynthetic activities of producers in
the form of organic substances, used as food
materials. The rates of energy storage at
consumer levels are referred to as Secondary
Productivity.
Gross Primary Productivity: It is the total
rate of photosynthesis, including the
organic matter used up in respiration
during the period of measurement. This is
also called Total Photosynthesis or Total
Assimilation.
Net Primary Productivity: It is the rate of
storage of organic matter in plant tissue in
excess of that utilized in respiration by
plants during the period of measurement.
This is also called Apparent Photosynthesis
or Net Assimilation.
Net productivity: Net productivity of a
community is the rate of storage of organic
matter not used by heterotrophs i.e. net
primary production minus heterotrophic
consumption, during the period under
consideration.
Biogeochemical Cycles: More or less
circular pathways, through which the
chemical elements, including all the essential
elements of the protoplasm, circulate in the
biosphere from environment to organisms
and back to the environment, are known
as the biogeochemical cycles.
Ecological Niche: Ecological niche of an
organism include the physical space
occupied by it, its functional role in the
community i.e. trophic position, and its
position in environment gradients of
temperature, moisture, pH of soil, etc. and
the conditions of existence. Organisms that
occupy the same or similar ecological niche
in different geographical regions are known
as Ecological Equivalents
Species: A species is a natural biological
unit tied together by the sharing of a
common gene pool. It can be also defined
as a uniform interbreeding population
spread over time and space.
Vegetation: The collective and continuous
growth of plants in space is called
vegetation. Thus, vegetation is actually the
totality of plant growth, including large or
small populations of each species
intermixed in a region. In other words we
may say that vegetation is the sum total of
plant population covering a region.
Flora: Flora is the species content of the
region irrespective of the numerical strength
of each species.
Population: A population is a group of
individual organisms of the same species
in a given area.
Community: A community is a group of
population of different species in a givenarea. It thus includes all the populations in
that area- all plants, all animals and
microorganisms.
Factor: Any external force, substance or
condition that affects organisms in any
way, is known as factor.
Environment: The sum of all factors
constitute environment. It thus becomes
indeed a complex of so many factors, better
referred to as environmental complex.
Habitat: The place, where an organism
lives, or the place where one would go to
find the particular organism is known as
the habitat of that organism. The habitat
of an organism actually represents a
particular set of environmental conditions
suitable for its successful growth.
Adaptation: Any species puts its efforts to
make full use of the available nutrient pool
and other environmental conditions
prevailing in the area of its growth. It
ensures its own protection against adverse
conditions of the habitat. This all is
accomplished by the development of some
characteristics.
ECAD: Some of the species have more than
one kind of populations spread over wide
range of habitat conditions. An ecad of a
plant species is a population of individuals
which although belong to the same genetic
stock, but differ markedly in vegetative
characters such as size, shape, number of
leaves, stems, etc. These variations are
simply environmentally induced, and thus
are temporary or reversible i.e. one type of
ecad may change into another with the
change in its habitat.
Ecotype: An ecotype is a population of
individuals of a species, which are
genetically different. Since different
ecotypes are inter-fertile, these are kept
under the same taxonomic species. Their
variations are permanent and irreversible
as these are genetically fixed.
Eco-tone: Although plant species grow in
association with each other in groups as
communities in nature, there is hardly
distinguishable a point or sharp line of
distinction between the two different
communities. There is generally a zone of
transition, presenting a situation of special
ecological interest between two different
types of communities, which is known as
an eco-tone.
Life Form: A life form is the sum of the
adaptation of the plant to the climate. This
view point is considered in the
physiognomic method of study of plant
communities.
Biological Spectrum: The percentage
distribution of species among the various
life forms of a flora is called the biological
spectrum of that place.
Ecological Succession: Vegetation is hardly
stable, and thus dynamic, changing over
time and space. Although comparatively
less evident than vegetation, animal
populations, particularly lower forms, also
show dynamic character to some extent.
Succession is a natural process by which
different groups or communities colonize
the same area over a period of time in a
definite sequence. The succession, which
starts from a primitive substratum without
any previous living matter, is known as the
primary succession, whereas that starting
from the previously built up substratum
where living matter already existed, is
known as the secondary succession. If the
existing community, as a result of its
reaction with the environment, causes its
own replacement, then such a succession
is known as autogenic succession but if the
replacement of the existing community
takes place due to the influence of any
external force or condition, then it is called
allogenic succession.
Climax: In the natural process of
succession, one community continues to
follow another, until a stage comes when a
type of community cannot be displaced
under the prevailing environmental
conditions. This final, terminal community,
that can maintain itself more or less
indefinitely in equilibrium with the
prevailing environment, is known as the
climax community and the stage is said to
be the climax.
Biome: A complex of several types of
communities, some in climax stage and
others in different stages of succession,
maintained more or less similar climatic
conditions is known as a biome.
Ecosystem: In a given area, the biotic assemblage of all the organisms, plant as
well as animal communities, interacts with
its physical environment in such a manner
that there is a flow of energy leading to
clearly defined trophic structure, biotic
diversity and material cycles within a
system, is known as an ecological system
or ecosystem. An ecosystem is the whole
biotic community in a given area plus its
abiotic environment.
Biosphere: The earth’s living organisms
interacting with their physical environment
may be considered as a giant ecosystem,
which is the largest and most nearly selfsufficient
biological system we know, and
this is designated as the biosphere or
ecosphere. Thus the planet earth along with
the atmosphere, hydrosphere and
lithosphere which sustain life is known as
biosphere.
Standing State: The amount of inorganic
substances, such as P, S, C, N, H etc. present
at any given time in the environment of an
ecosystem, is known as the standing state
or standing quality.
Standing Crop: The amount of living
material, present in a component
population at any time, is known as the
standing crop, which may be expressed in
terms of numbers or weight per unit area.
Biomass: Biomass is the standing crop
expressed in terms of weight (i.e. organism
mass) of the living matter present.
Food Chain: In any ecosystem, various living
organisms are arranged in a definite sequence
according to their food habits. Plants are
producers which are eaten by herbivores,
which in turn are eaten by carnivores. This
transfer of food energy from the source in
plants through a series of organisms with
repeated eating and being eaten is known as
a food chain in an ecosystem.
Food Web: Under natural conditions in the
same ecosystem, depending upon the
variety of organisms, there generally
operate a number of linear food chains at
a time. These chains are interlinked with
each other at several points. This
interlocking pattern of a number of food
chains forms a web-like arrangement
known as food-web.
Productivity: The rate of production i.e.
amount of organic matter accumulated in
the living component of an ecosystem in
unit time is referred to as the productivity
of the ecosystem. Primary Productivity is
defined as the rate at which radiant energy
of sun is stored by photosynthetic and
chemosynthetic activities of producers in
the form of organic substances, used as food
materials. The rates of energy storage at
consumer levels are referred to as Secondary
Productivity.
Gross Primary Productivity: It is the total
rate of photosynthesis, including the
organic matter used up in respiration
during the period of measurement. This is
also called Total Photosynthesis or Total
Assimilation.
Net Primary Productivity: It is the rate of
storage of organic matter in plant tissue in
excess of that utilized in respiration by
plants during the period of measurement.
This is also called Apparent Photosynthesis
or Net Assimilation.
Net productivity: Net productivity of a
community is the rate of storage of organic
matter not used by heterotrophs i.e. net
primary production minus heterotrophic
consumption, during the period under
consideration.
Biogeochemical Cycles: More or less
circular pathways, through which the
chemical elements, including all the essential
elements of the protoplasm, circulate in the
biosphere from environment to organisms
and back to the environment, are known
as the biogeochemical cycles.
Ecological Niche: Ecological niche of an
organism include the physical space
occupied by it, its functional role in the
community i.e. trophic position, and its
position in environment gradients of
temperature, moisture, pH of soil, etc. and
the conditions of existence. Organisms that
occupy the same or similar ecological niche
in different geographical regions are known
as Ecological Equivalents
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