Organisation at the Ecosystem Level 57
Thus, energy flow from the ecosystem to the environment and reverse
is mainly dependent on the basic chemical reactions of photosynthesis
and respiration:
CO H O radiation organic matter O (photosynthe
2
2
2
+
+
→
+
s sis)
Organic matter O
CO H O heat(respiration
+
→
+
+
2
2
2
) ).
It is obvious that the relationship between incoming energy (radiation)
and outgoing energy (heat) results in a corresponding relationship between
the incoming and outgoing CO 2 quantity as well as between the incoming
and outgoing O 2 quantity. Thus:
• If E = 0, then the ecosystem is in energy balance with its environment
and its total biomass does not change. The CO 2 quantities absorbed
and emitted by the ecosystem are equivalent, and the same is true for
the absorbed and emitted O 2 quantities. This represents the case of an
ecosystem in a condition of stable equilibrium, as e.g. a mature forest.
• If E > 0, the ecosystem is an O 2 producer and CO 2 consumer. The
absorbed CO 2 quantities are greater than the emitted ones, whereas
the opposite is true for O 2 . In this case there is an energy inflow in the
ecosystem and its total biomass increases; therefore it is in a developmental phase.
• If E < 0, the ecosystem is an O 2 consumer and CO 2 producer. The
absorbed CO 2 quantities are less than the emitted ones, while the
opposite is true for O 2 . Energy balance is negative and its total biomass decreases. This is an ecosystem in a shrinking phase.
If E > 0 or E < 0 or E = 0, it does not necessarily follow that all biomasses of
individual compartments are increased, decreased or remain stable, respectively.
From the above, it becomes evident that a mature ecosystem, i.e. an ecosystem that does not develop anymore because it has reached an energy
balance, does not produce O 2 nor consumes CO 2 . On the contrary, these
results are mainly produced by developing ecosystems (e.g. a growing forest
or a new forest settling in an open space) or ecosystems, part of the production of which does not decompose but is removed by man (e.g. agrosystems,
forests under exploitation).
During some geological eras (e.g. carboniferous), Earth’s ecosystem,
i.e. the biosphere, was in E > 0 states. During such periods fossil fuel deposits
were created, because the increasing biomass could not be decomposed and
was stored in the ground; thus, the additional energy of the ecosystem was
stored in the form of chemical energy of the fuel. On the other hand, there
were situations when E < 0, such as the dinosaurs’ extinction period or
periods of extensive forest fires or of other analogous destructions.
Thus, energy flow from the ecosystem to the environment and reverse
is mainly dependent on the basic chemical reactions of photosynthesis
and respiration:
CO H O radiation organic matter O (photosynthe
2
2
2
+
+
→
+
s sis)
Organic matter O
CO H O heat(respiration
+
→
+
+
2
2
2
) ).
It is obvious that the relationship between incoming energy (radiation)
and outgoing energy (heat) results in a corresponding relationship between
the incoming and outgoing CO 2 quantity as well as between the incoming
and outgoing O 2 quantity. Thus:
• If E = 0, then the ecosystem is in energy balance with its environment
and its total biomass does not change. The CO 2 quantities absorbed
and emitted by the ecosystem are equivalent, and the same is true for
the absorbed and emitted O 2 quantities. This represents the case of an
ecosystem in a condition of stable equilibrium, as e.g. a mature forest.
• If E > 0, the ecosystem is an O 2 producer and CO 2 consumer. The
absorbed CO 2 quantities are greater than the emitted ones, whereas
the opposite is true for O 2 . In this case there is an energy inflow in the
ecosystem and its total biomass increases; therefore it is in a developmental phase.
• If E < 0, the ecosystem is an O 2 consumer and CO 2 producer. The
absorbed CO 2 quantities are less than the emitted ones, while the
opposite is true for O 2 . Energy balance is negative and its total biomass decreases. This is an ecosystem in a shrinking phase.
If E > 0 or E < 0 or E = 0, it does not necessarily follow that all biomasses of
individual compartments are increased, decreased or remain stable, respectively.
From the above, it becomes evident that a mature ecosystem, i.e. an ecosystem that does not develop anymore because it has reached an energy
balance, does not produce O 2 nor consumes CO 2 . On the contrary, these
results are mainly produced by developing ecosystems (e.g. a growing forest
or a new forest settling in an open space) or ecosystems, part of the production of which does not decompose but is removed by man (e.g. agrosystems,
forests under exploitation).
During some geological eras (e.g. carboniferous), Earth’s ecosystem,
i.e. the biosphere, was in E > 0 states. During such periods fossil fuel deposits
were created, because the increasing biomass could not be decomposed and
was stored in the ground; thus, the additional energy of the ecosystem was
stored in the form of chemical energy of the fuel. On the other hand, there
were situations when E < 0, such as the dinosaurs’ extinction period or
periods of extensive forest fires or of other analogous destructions.