74 Ecology and Applied Environmental Science
rich plant life, herbivorous animals will invade the area and the carnivores
will follow, until a complete ecosystem is formed.
Phenomena of successive biological communities’ creation are called
ecological succession. The succession continues until a mature and relatively stable (climax) biocoenosis is formed, which is characteristic of the
specific climate and soil of the area. During the succession, at least in the
initial stages, species diversity increases and the trophic dependence among
species tends to form a complex network.
We can distinguish between primary and secondary succession. The first
begins in places where ecological functions develop on a previously abiotic
environ ment. The second takes place when an existing biocoenosis has
been degraded or destroyed and is gradually recovering through successive
pioneer biocommunities. A classic example of primary succession is ecosystem creation in a new volcanic island. Another example is the phenomenon
where natural sand dunes act as barriers and create shallow coastal lakes
that may gradually develop into forests. Secondary succession is observed
when a forest burns down and the natural vegetation is regenerated and
forms successive phytocoenoses that ultimately become a mature forest.
Another example is the development of a new biocoenosis where the waste
of various organisms has contributed to the creation of soil.
4.4.2 complexity and Stability of Ecosystems
sistence is observed, whereas at lower levels, such as populations, for example, there is no steadiness. Linking ecosystem’s persistence with diversity
or with the complexity of the ecosystem’s trophic networks has been suggested; this idea is only partially accepted and the question remains open.
A system’s persistence means that the system permanently remains more
or less in the same state, which is connected with stability or resilience,
i.e. its endurance against perturbations. Cohesion of a system is the total
of the relations that connect its parts. The complexity of a system corresponds to the number of sub-systems that can co-operate for some goal,
whereas diversity corresponds to the number of sub-systems that can act
independently. In the case of ecosystems, diversity can be conceived as the
number of the ecosystem’s different species or as a mathematical expression
that depends on that number. It is obvious that a greater species’ diversity
means a greater possibility for the existence of multiple networks of relationships and therefore of greater complexity as well. In this case, a consumer
organism’s population can use other populations for food and the system
eventually has increased ability for resistance to perturbations.
There must be a distinction between the ecosystem’s ability to be stable
in the face of small perturbations and its corresponding ability (resilience)
to return to its previous state after great perturbations. Great complexity
rich plant life, herbivorous animals will invade the area and the carnivores
will follow, until a complete ecosystem is formed.
Phenomena of successive biological communities’ creation are called
ecological succession. The succession continues until a mature and relatively stable (climax) biocoenosis is formed, which is characteristic of the
specific climate and soil of the area. During the succession, at least in the
initial stages, species diversity increases and the trophic dependence among
species tends to form a complex network.
We can distinguish between primary and secondary succession. The first
begins in places where ecological functions develop on a previously abiotic
environ ment. The second takes place when an existing biocoenosis has
been degraded or destroyed and is gradually recovering through successive
pioneer biocommunities. A classic example of primary succession is ecosystem creation in a new volcanic island. Another example is the phenomenon
where natural sand dunes act as barriers and create shallow coastal lakes
that may gradually develop into forests. Secondary succession is observed
when a forest burns down and the natural vegetation is regenerated and
forms successive phytocoenoses that ultimately become a mature forest.
Another example is the development of a new biocoenosis where the waste
of various organisms has contributed to the creation of soil.
4.4.2 complexity and Stability of Ecosystems
sistence is observed, whereas at lower levels, such as populations, for example, there is no steadiness. Linking ecosystem’s persistence with diversity
or with the complexity of the ecosystem’s trophic networks has been suggested; this idea is only partially accepted and the question remains open.
A system’s persistence means that the system permanently remains more
or less in the same state, which is connected with stability or resilience,
i.e. its endurance against perturbations. Cohesion of a system is the total
of the relations that connect its parts. The complexity of a system corresponds to the number of sub-systems that can co-operate for some goal,
whereas diversity corresponds to the number of sub-systems that can act
independently. In the case of ecosystems, diversity can be conceived as the
number of the ecosystem’s different species or as a mathematical expression
that depends on that number. It is obvious that a greater species’ diversity
means a greater possibility for the existence of multiple networks of relationships and therefore of greater complexity as well. In this case, a consumer
organism’s population can use other populations for food and the system
eventually has increased ability for resistance to perturbations.
There must be a distinction between the ecosystem’s ability to be stable
in the face of small perturbations and its corresponding ability (resilience)
to return to its previous state after great perturbations. Great complexity