52 Ecology and Applied Environmental Science
i.e. a superior trophic level. A part of this biomass is utilized and the rest
is discarded; consequently, the consumption amount can be analysed in
assimilation and waste. From the assimilation amount a part is ultimately
transformed in heat and discarded through respiration, whereas the rest
constitutes the trophic level production. In its turn, this can be utilized as
food for a subsequent trophic level.
According to the above, the energy magnitudes of a population or ecosystem are connected through the following relationships:
C A W
A R P
= +
= +
where C is consumption, A assimilation, W waste, R respiration and P
production.
4.1.1 Food chains—trophic levels
On the basis of their position in the ecosystem from an energy flow aspect,
organisms are divided as follows:
• Producers are the autotrophic-photosynthetic organisms. These have
the fundamental capability to produce synthetic organic matter using
inorganic matter along with solar energy. Plants are the producers in
terrestrial ecosystems, while in aquatic ecosystems they are mostly algae.
• Consumers are heterotrophic-chemosynthetic organisms, apart from
bacteria and fungi. They are only capable of composing organic
matter after obtaining carbon and energy from the producers.
Energy
ECOSYSTEM
Energy
Chemical
element
Chemical
element
Chemical
element
Figure 4.1 Energy and matter flow. (From Hadjibiros, K. (2007). Ecology. Ecosystems
and Environmental Protection, 3rd edition. Symmetria, Athens (in Greek).
With permission.)
i.e. a superior trophic level. A part of this biomass is utilized and the rest
is discarded; consequently, the consumption amount can be analysed in
assimilation and waste. From the assimilation amount a part is ultimately
transformed in heat and discarded through respiration, whereas the rest
constitutes the trophic level production. In its turn, this can be utilized as
food for a subsequent trophic level.
According to the above, the energy magnitudes of a population or ecosystem are connected through the following relationships:
C A W
A R P
= +
= +
where C is consumption, A assimilation, W waste, R respiration and P
production.
4.1.1 Food chains—trophic levels
On the basis of their position in the ecosystem from an energy flow aspect,
organisms are divided as follows:
• Producers are the autotrophic-photosynthetic organisms. These have
the fundamental capability to produce synthetic organic matter using
inorganic matter along with solar energy. Plants are the producers in
terrestrial ecosystems, while in aquatic ecosystems they are mostly algae.
• Consumers are heterotrophic-chemosynthetic organisms, apart from
bacteria and fungi. They are only capable of composing organic
matter after obtaining carbon and energy from the producers.
Energy
ECOSYSTEM
Energy
Chemical
element
Chemical
element
Chemical
element
Figure 4.1 Energy and matter flow. (From Hadjibiros, K. (2007). Ecology. Ecosystems
and Environmental Protection, 3rd edition. Symmetria, Athens (in Greek).
With permission.)