Organisation at the Ecosystem Level 63
respective adjustments in other parts. Thus, the presence of cycles gives the
biosphere a remarkable self-regulation capability. The result is the observed
long-term stability of the various ecosystems, along with the continuous
presence of essential substances in the various environments in generally
stable analogies. Therefore, life and mainly producer organisms have the
ability to obtain the substances they need from the space they live in.
The matter that moves in a biogeochemical cycle is often stored for a
specific time frame in some abiotic or biotic component of the ecosystem,
which is called a reservoir. The stored matter quantity is the storage,
whereas the quantity that is transferred between reservoirs per unit time is
the flow velocity. In an ecosystem that is in a state of equilibrium, R i = R k
applies, where R i is the sum of inflow velocities and R k is the sum of outflow velocities from one reservoir. Turnover time is the magnitude T, equal
to M/R i or M/R k , where M = storage. T can be considered as the mean
time that the matter remains within the reservoir. It serves as a sensitivity measure of a component of the ecosystem versus the variations caused
by human activity in the biogeochemical cycles. Greater T periods indicate greater resistance in velocity flow variations. It has been estimated
that time T in the reservoir “atmosphere” is for N 2 64 x 10 6 years, for O 2
7500 years and for CO 2 5 years.
Most important are the biogeochemical cycles of H 2 O, C, O 2 , N 2 , P,
and S. It should be noted that chemical element’s circulation within the
Bioelements
in solution
OCEAN
Precipitation
Weathering
Terrestrial biosphere
Decomposition
Losses
by water runoff
Volatile
bioelements only
Evaporation
Sinking
H 2 O
(+ volatile
biochemicals)
Death
Uptake
Dead organic
matter
Marine
food web
Dead organic
matter
Terrestrial
food web
Volatile
bioelements only
Figure 4.4 General schematic of nutrient cycling on a global scale. Movement of nonvolatile elements, such as phosphorus, is largely one way, toward ocean sediments. (From De Angelis, D.L. (1992). Dynamics of Nutrient Cycling and Food
Webs. Chapman & Hall, London; and Krebs, C.J. (2001). Ecology. Benjamin
Cummings, San Francisco, CA. With kind permission from Springer Science
+ Business Media B.V.)
respective adjustments in other parts. Thus, the presence of cycles gives the
biosphere a remarkable self-regulation capability. The result is the observed
long-term stability of the various ecosystems, along with the continuous
presence of essential substances in the various environments in generally
stable analogies. Therefore, life and mainly producer organisms have the
ability to obtain the substances they need from the space they live in.
The matter that moves in a biogeochemical cycle is often stored for a
specific time frame in some abiotic or biotic component of the ecosystem,
which is called a reservoir. The stored matter quantity is the storage,
whereas the quantity that is transferred between reservoirs per unit time is
the flow velocity. In an ecosystem that is in a state of equilibrium, R i = R k
applies, where R i is the sum of inflow velocities and R k is the sum of outflow velocities from one reservoir. Turnover time is the magnitude T, equal
to M/R i or M/R k , where M = storage. T can be considered as the mean
time that the matter remains within the reservoir. It serves as a sensitivity measure of a component of the ecosystem versus the variations caused
by human activity in the biogeochemical cycles. Greater T periods indicate greater resistance in velocity flow variations. It has been estimated
that time T in the reservoir “atmosphere” is for N 2 64 x 10 6 years, for O 2
7500 years and for CO 2 5 years.
Most important are the biogeochemical cycles of H 2 O, C, O 2 , N 2 , P,
and S. It should be noted that chemical element’s circulation within the
Bioelements
in solution
OCEAN
Precipitation
Weathering
Terrestrial biosphere
Decomposition
Losses
by water runoff
Volatile
bioelements only
Evaporation
Sinking
H 2 O
(+ volatile
biochemicals)
Death
Uptake
Dead organic
matter
Marine
food web
Dead organic
matter
Terrestrial
food web
Volatile
bioelements only
Figure 4.4 General schematic of nutrient cycling on a global scale. Movement of nonvolatile elements, such as phosphorus, is largely one way, toward ocean sediments. (From De Angelis, D.L. (1992). Dynamics of Nutrient Cycling and Food
Webs. Chapman & Hall, London; and Krebs, C.J. (2001). Ecology. Benjamin
Cummings, San Francisco, CA. With kind permission from Springer Science
+ Business Media B.V.)