environment, develop and maintain ecosystemic processes – biomass production,
consumption and decay of necromass; this way the populations influence in their
turn the abiotic environment.
In all these studies the ecologic aspect of populations was taken into consideration, which were denominated as «ecological populations».
We think that too little attention was paid to the role of populations – as
ecological entities – within the structure and processes of the species.
The population of a species appears only in certain biocoenosis – namely in that
where it may develop and reproduce within the characteristic ecological niche of
that species. These characteristics determine the size of the population and the its
role in the processes running within that biocoenosis. Depending on these biotic and
abiotic relations, a population may appear (or not) in a certain biocoenosis.
Within the framework of a biocoenosis there are some species whose
populations play a prevailing role within its entire activity and, also, occur
populations with a secondary, even minor role. From the ecological point of
view, in a biocoenosis the population of a species is a feature that may be
characterized through the frequency of its occurrence, through the constance of
its appearance (as accidental, accesory or constant presence), through the fidelity to
respective biocoenosis (being a characteristic, preferential, casual or ubiquiste
species), through density (high or low); it may belong to a specific trophic level,
or may represent a true knot within the trophic network of the respective biocoenosis are ensured.
As a consequence, the species is not a simple multitude of similar organisms
randomly occurring in a geographic space called areal, but forms units composed of
populations which exist only in certain types of ecosystems within that areal. These
types represent in fact the definite areal of the species, which was described as
«ecological areal» (Donita and Ivan 1977; Godeanu 1998).
Populations of a species occurring in a precise type of ecosystem are similar,
because they develop under similar biotic and abiotic conditions and may be
classified in types of populations. There are certain species whose populations
occur in a single type of ecosystem – as the characteristic species for a certain
ecosystem. There are also some species with a simple populational structure,
unipopulational, characterized by a reduced ecological amplitude. Most are the
species with a more complex populational structure, which apprear in several, even
in more types of ecosystems. They are multipopulational species, with a large
ecological amplitude, sometimes even very large – as the invasive species, the
dominant species etc.
The ecological population is an example of how, through a simple element,
simultaneously, the building up and the functioning of the species and the biocoenosis are ensured.
In biological research it is well known that every species occupies a certain
territory, which is called an areal. Within this areal, the occurrence of the species
may be continuous or discontinuous. In the case of the species with a large areal,
there may appear some more or less distinct subspecies (hence, speciation occurs
through disjunctive evolution).
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N. Donița ˘ and S. Godeanu
consumption and decay of necromass; this way the populations influence in their
turn the abiotic environment.
In all these studies the ecologic aspect of populations was taken into consideration, which were denominated as «ecological populations».
We think that too little attention was paid to the role of populations – as
ecological entities – within the structure and processes of the species.
The population of a species appears only in certain biocoenosis – namely in that
where it may develop and reproduce within the characteristic ecological niche of
that species. These characteristics determine the size of the population and the its
role in the processes running within that biocoenosis. Depending on these biotic and
abiotic relations, a population may appear (or not) in a certain biocoenosis.
Within the framework of a biocoenosis there are some species whose
populations play a prevailing role within its entire activity and, also, occur
populations with a secondary, even minor role. From the ecological point of
view, in a biocoenosis the population of a species is a feature that may be
characterized through the frequency of its occurrence, through the constance of
its appearance (as accidental, accesory or constant presence), through the fidelity to
respective biocoenosis (being a characteristic, preferential, casual or ubiquiste
species), through density (high or low); it may belong to a specific trophic level,
or may represent a true knot within the trophic network of the respective biocoenosis are ensured.
As a consequence, the species is not a simple multitude of similar organisms
randomly occurring in a geographic space called areal, but forms units composed of
populations which exist only in certain types of ecosystems within that areal. These
types represent in fact the definite areal of the species, which was described as
«ecological areal» (Donita and Ivan 1977; Godeanu 1998).
Populations of a species occurring in a precise type of ecosystem are similar,
because they develop under similar biotic and abiotic conditions and may be
classified in types of populations. There are certain species whose populations
occur in a single type of ecosystem – as the characteristic species for a certain
ecosystem. There are also some species with a simple populational structure,
unipopulational, characterized by a reduced ecological amplitude. Most are the
species with a more complex populational structure, which apprear in several, even
in more types of ecosystems. They are multipopulational species, with a large
ecological amplitude, sometimes even very large – as the invasive species, the
dominant species etc.
The ecological population is an example of how, through a simple element,
simultaneously, the building up and the functioning of the species and the biocoenosis are ensured.
In biological research it is well known that every species occupies a certain
territory, which is called an areal. Within this areal, the occurrence of the species
may be continuous or discontinuous. In the case of the species with a large areal,
there may appear some more or less distinct subspecies (hence, speciation occurs
through disjunctive evolution).
510
N. Donița ˘ and S. Godeanu