3
These tanks also serve for groundwater recharging. However, the tanks of Kaspadi, Ulluru and
Govatooru are, at present, in bad condition due to
various anthropogenic stresses. Increased macrophytic growth and unhygienic conditions prevailing in the tanks have caused damage. The marshy
areas are the places for mosquito breeding and
these areas are being turned into paddy fi elds
by the encroachers. The water-holding capacity
of these tanks seems to be decreasing due to these
activities. An almost similar situation also prevails in other parts of India.
In this connection, studies are being undertaken to illustrate the present status of wetlands
and the stresses acting upon them and also to
highlight the requirement of their restoration and
economic valuation.
1.6
Defi nition of Certain General
Ecological Terms
1.6.1 Population
This term is used mainly to mean a collection of
individuals belonging to one species, within a
defi ned area or volume. In short, a population is
any unispecifi c collection of organisms in a discrete space or area.
1.6.2 Assemblage
This term is used mainly to mean a collection of
individuals belonging to different species, within
a defi ned area or volume. In short, an assemblage
is a collection of co-occurring populations.
1.6.3 Biotope
This term was introduced by Dahl ( 1908 ) to designate the kinds of terrestrial or aquatic environments in which organisms occur. In brief, a
biotope may be defi ned as any segment of the
biosphere with convenient arbitrary upper and
lower boundaries, which is horizontally and
homogeneously diverse in relation to the larger
motile organisms present within it.
1.6.4 Biocoenosis
This term was coined by Mobius ( 1877 ) in order
to designate the entire biological community of a
defi ned area, in which individuals of different
species live side by side and persist by virtue of
their reproductive activity. Later workers used
this term in different senses (Hesse 1924 ;
Friederichs 1927 ). In short, a biocoenosis is the
totality of organisms living in a biotope or the living part of an ecosystem (Tansley 1935 ). A biocoenosis is said to represent a more empirical
unit than the biome (Clements and Shelford
1939 ), which is an ideal construction containing
not only climax and successional stages but
various arrested stages resulting from defl ected
succession.
The biocoenosis on land is equivalent to the
formation of botanical ecologists, save that it is
empirically restricted to a particular area and not
the class of all similar areas.
1.6.5 Association, Niche
and Habitat
The only divisions of the biocoenosis that seem to
have real signifi cance in ecological limnology are
what would be termed associations . Such parts of
the biocoenosis are those that can be characterised
by dominant or at least characteristic species. The
concept of association is certainly useful for plant,
animal or mixed communities. It inevitably has an
arbitrary size parameter which cannot be dealt
with by a concept of homogeneous diversity but
must remain relative to the visual fi eld of the
investigator. In brief, the term association is ordinarily used for an assembly of species that recurs
under comparable ecological conditions in different places. We may recognise association of
species within a biocoenosis.
The niche of a species is defi ned purely intensively. It is assumed that all the variation of the
1.6 Defi nition of Certain General Ecological Terms
These tanks also serve for groundwater recharging. However, the tanks of Kaspadi, Ulluru and
Govatooru are, at present, in bad condition due to
various anthropogenic stresses. Increased macrophytic growth and unhygienic conditions prevailing in the tanks have caused damage. The marshy
areas are the places for mosquito breeding and
these areas are being turned into paddy fi elds
by the encroachers. The water-holding capacity
of these tanks seems to be decreasing due to these
activities. An almost similar situation also prevails in other parts of India.
In this connection, studies are being undertaken to illustrate the present status of wetlands
and the stresses acting upon them and also to
highlight the requirement of their restoration and
economic valuation.
1.6
Defi nition of Certain General
Ecological Terms
1.6.1 Population
This term is used mainly to mean a collection of
individuals belonging to one species, within a
defi ned area or volume. In short, a population is
any unispecifi c collection of organisms in a discrete space or area.
1.6.2 Assemblage
This term is used mainly to mean a collection of
individuals belonging to different species, within
a defi ned area or volume. In short, an assemblage
is a collection of co-occurring populations.
1.6.3 Biotope
This term was introduced by Dahl ( 1908 ) to designate the kinds of terrestrial or aquatic environments in which organisms occur. In brief, a
biotope may be defi ned as any segment of the
biosphere with convenient arbitrary upper and
lower boundaries, which is horizontally and
homogeneously diverse in relation to the larger
motile organisms present within it.
1.6.4 Biocoenosis
This term was coined by Mobius ( 1877 ) in order
to designate the entire biological community of a
defi ned area, in which individuals of different
species live side by side and persist by virtue of
their reproductive activity. Later workers used
this term in different senses (Hesse 1924 ;
Friederichs 1927 ). In short, a biocoenosis is the
totality of organisms living in a biotope or the living part of an ecosystem (Tansley 1935 ). A biocoenosis is said to represent a more empirical
unit than the biome (Clements and Shelford
1939 ), which is an ideal construction containing
not only climax and successional stages but
various arrested stages resulting from defl ected
succession.
The biocoenosis on land is equivalent to the
formation of botanical ecologists, save that it is
empirically restricted to a particular area and not
the class of all similar areas.
1.6.5 Association, Niche
and Habitat
The only divisions of the biocoenosis that seem to
have real signifi cance in ecological limnology are
what would be termed associations . Such parts of
the biocoenosis are those that can be characterised
by dominant or at least characteristic species. The
concept of association is certainly useful for plant,
animal or mixed communities. It inevitably has an
arbitrary size parameter which cannot be dealt
with by a concept of homogeneous diversity but
must remain relative to the visual fi eld of the
investigator. In brief, the term association is ordinarily used for an assembly of species that recurs
under comparable ecological conditions in different places. We may recognise association of
species within a biocoenosis.
The niche of a species is defi ned purely intensively. It is assumed that all the variation of the
1.6 Defi nition of Certain General Ecological Terms