26 Ecology and Applied Environmental Science
conditions. Generally, in an ecosystem there is a one-to-one correspondence
between the total of the populations and the total of available niches. The
sional super-space, where each dimension represents an important ecological parameter and within which the environment allows the survival of the
population. The preservation of a species is connected with securing its
populations’ ecological niche in the biosphere.
A sub-total of the concept “ecological niche” is the ecological habitat,
i.e. the set of the geographical, abiotic and biotic conditions of the natural
environment that suit a population. In the past, the biotope had a similar
meaning. Currently, the term biotope is mostly used to define a geographical area important for the conservation of the natural environment because
one or more protected biological species dwell there. The adoption of the
biotope concept gives an existing and expanding use of the term.
The growth of a population is affected both by its internal forces and
external factors. As a rule, the population has an internal tendency to
increase with a fixed rate per individual, which initially leads to an exponential change. However, the rate of increase is usually halted under the
influence of abiotic environmental factors such as temperature, radiation,
humidity, nutrients etc. or biotic environmental factors such as simple or
complex population interactions within the ecosystem. One of these factors
emerges in each case as the limiting factor.
A population’s size change in time basically depends on three parameters:
• Natality rate
• Mortality rate
• Immigration rates of individuals to and from the population
The examination of temporal change within animal and plant populations, as well as that of the human population, has always been of vast
practical importance. That is why many mathematical methods of study,
mainly of empirical/statistical character, were developed a long time ago
in order to assess these phenomena; these methods belong to population
dynamics and demography.
3.1.1 age distribution
Each population can be subdivided into age groups. All the individuals
of a population whose age lies within a specific age span belong to the
corresponding group. For example, from 100 individuals of a human population, 20 may be children (0–15 years), 15 may be youngsters (15–25),
40 mature (25–60) and 25 elderly (over 60) (Figures 3.1, 3.2 and 3.3).
Characteristic age distributions of human populations are shown in
Figure 3.4.
conditions. Generally, in an ecosystem there is a one-to-one correspondence
between the total of the populations and the total of available niches. The
sional super-space, where each dimension represents an important ecological parameter and within which the environment allows the survival of the
population. The preservation of a species is connected with securing its
populations’ ecological niche in the biosphere.
A sub-total of the concept “ecological niche” is the ecological habitat,
i.e. the set of the geographical, abiotic and biotic conditions of the natural
environment that suit a population. In the past, the biotope had a similar
meaning. Currently, the term biotope is mostly used to define a geographical area important for the conservation of the natural environment because
one or more protected biological species dwell there. The adoption of the
biotope concept gives an existing and expanding use of the term.
The growth of a population is affected both by its internal forces and
external factors. As a rule, the population has an internal tendency to
increase with a fixed rate per individual, which initially leads to an exponential change. However, the rate of increase is usually halted under the
influence of abiotic environmental factors such as temperature, radiation,
humidity, nutrients etc. or biotic environmental factors such as simple or
complex population interactions within the ecosystem. One of these factors
emerges in each case as the limiting factor.
A population’s size change in time basically depends on three parameters:
• Natality rate
• Mortality rate
• Immigration rates of individuals to and from the population
The examination of temporal change within animal and plant populations, as well as that of the human population, has always been of vast
practical importance. That is why many mathematical methods of study,
mainly of empirical/statistical character, were developed a long time ago
in order to assess these phenomena; these methods belong to population
dynamics and demography.
3.1.1 age distribution
Each population can be subdivided into age groups. All the individuals
of a population whose age lies within a specific age span belong to the
corresponding group. For example, from 100 individuals of a human population, 20 may be children (0–15 years), 15 may be youngsters (15–25),
40 mature (25–60) and 25 elderly (over 60) (Figures 3.1, 3.2 and 3.3).
Characteristic age distributions of human populations are shown in
Figure 3.4.