Organisation at the Ecosystem Level 59
the case when the values of factors fluctuate naturally. The existence of
a limiting factor leads the respective population or part of the ecosystem
to an increase with self-limitation (Chapter 3). The limit of this increase,
i.e. the carrying capacity of the environment, is each time determined by
the limiting factor. The possible absence of a limiting factor in a sector or
phase of the ecosystem leads to an exponential increase state.
The notion of the limiting factor allows the comprehension of essential
ecological phenomena, without the necessity of a detailed analysis of the
structure and functions of the respective ecosystems. The value of this
approach is due to the fact that the researcher can explore the ecosystem,
thus “starting a thread” through complicated situations. However, this is
not always applicable in transitional or swiftly changing ecosystem states,
but mostly in steady states close to the equilibrium point.
4.2.1 Primary Production
Primary production is defined by the efficiency of producer organisms and
essentially determines the productivity of the whole ecosystem (Table 4.1).
It depends on the following factors, one of which becomes, in each case,
the limiting factor:
• Radiation is the most important natural factor. Its daily and annual
periodicity regulates the activities of a large number of organisms.
It can become the limiting factor if its intensity is too low. Visible
light intensity is a function of the geographical amplitude, climate,
relief, orientation, water depth, transparency etc. In aquatic ecosystems, algae and aquatic plants do not develop in the absence of light,
because photosynthesis is not possible and productivity is nullified.
Therefore, light becomes the limiting factor in the dark depths of the
lakes or the sea, where it cannot penetrate. The same happens to all
ecosystems at night. During the winter, light may become a limiting
factor if its intensity is reduced. Intense ultraviolet radiation can also
become a limiting factor in terrestrial ecosystems (Chapter 9), since it
harms the organisms.
• Temperature is also an important natural factor and can become the
limiting factor when it reaches extreme values, e.g. in polar areas or
during the winter. Temperature variations are generally greater in
terrestrial than in aquatic ecosystems.
• Humidity, i.e. water, is a very important and often a limiting factor in
terrestrial ecosystems (e.g. desert) whereas it cannot, obviously, limit
aquatic ecosystems. In ecosystems such as wetlands water can become
a regulative factor. Salinity may have a corresponding part in coastal
wetlands. In terrestrial ecosystems, where water is not abundant ,
fire can become an important regulating factor.
the case when the values of factors fluctuate naturally. The existence of
a limiting factor leads the respective population or part of the ecosystem
to an increase with self-limitation (Chapter 3). The limit of this increase,
i.e. the carrying capacity of the environment, is each time determined by
the limiting factor. The possible absence of a limiting factor in a sector or
phase of the ecosystem leads to an exponential increase state.
The notion of the limiting factor allows the comprehension of essential
ecological phenomena, without the necessity of a detailed analysis of the
structure and functions of the respective ecosystems. The value of this
approach is due to the fact that the researcher can explore the ecosystem,
thus “starting a thread” through complicated situations. However, this is
not always applicable in transitional or swiftly changing ecosystem states,
but mostly in steady states close to the equilibrium point.
4.2.1 Primary Production
Primary production is defined by the efficiency of producer organisms and
essentially determines the productivity of the whole ecosystem (Table 4.1).
It depends on the following factors, one of which becomes, in each case,
the limiting factor:
• Radiation is the most important natural factor. Its daily and annual
periodicity regulates the activities of a large number of organisms.
It can become the limiting factor if its intensity is too low. Visible
light intensity is a function of the geographical amplitude, climate,
relief, orientation, water depth, transparency etc. In aquatic ecosystems, algae and aquatic plants do not develop in the absence of light,
because photosynthesis is not possible and productivity is nullified.
Therefore, light becomes the limiting factor in the dark depths of the
lakes or the sea, where it cannot penetrate. The same happens to all
ecosystems at night. During the winter, light may become a limiting
factor if its intensity is reduced. Intense ultraviolet radiation can also
become a limiting factor in terrestrial ecosystems (Chapter 9), since it
harms the organisms.
• Temperature is also an important natural factor and can become the
limiting factor when it reaches extreme values, e.g. in polar areas or
during the winter. Temperature variations are generally greater in
terrestrial than in aquatic ecosystems.
• Humidity, i.e. water, is a very important and often a limiting factor in
terrestrial ecosystems (e.g. desert) whereas it cannot, obviously, limit
aquatic ecosystems. In ecosystems such as wetlands water can become
a regulative factor. Salinity may have a corresponding part in coastal
wetlands. In terrestrial ecosystems, where water is not abundant ,
fire can become an important regulating factor.