Last update: 29/01/2007

Ecosystems

Today, we are always more aware that the environment is a living, fragile and complicated thing, based on a system of relationships that are established between all factors that determine the organization of life on the planet (cells, individuals, population, community, ecosystem, biome, biosphere).
Considering the complexity of environmental problems (whose dimensions can no longer be limited to national boundaries) and the growing awareness of the public opinion towards environmental issues, one of the solutions given by APAT and the Agencies System to carry out an efficient control activity is to integrate a culture of control with a culture of environmental protection.
Therefore, if we consider the environmental system within the framework of a set of ecosystems, in other words as an organizational level that expresses the relationships between its different parts, it becomes easier to note some fundamental features.
The system is:
1) open, since it receives and emanates matter and energy to the external world (therefore it does not follow the laws of classical thermodynamics which is limited to closed systems);
2) complex, because its description, even if summarized, requires several status variables;
3) ordered, because its parts are not homogeneous;
4) dynamic, because it continually changes towards a natural “maturity” stage (climax), which is generally not stationary but varies between average values and within the efficiency limits deriving from intrinsic homeostatic mechanisms.
When this normal ecological sequence is altered by serious interferences (mainly of human origin) or by great natural disasters and the “physiological” variations (that determine the balance between the biotic and abiotic component) exceed the whole ecosystem’s recovery limit, a process of degradation gets under way with a regression to less evolved biocenotic forms. This process can be reversed with environmental recovery action if the “environmental collapse” level (where the original status is definitely transformed) is not reached. In other words, a certain physical environment (or its biotic component) is stable if the changes it suffers are slight or of little importance such that it enables the living communities to adapt. But if there are major alterations and rapid change, extinction phenomena can be triggered or communities can be replaced with others that are more adequate to the new conditions.
Our experience over the last few years lead us to believe that all ecosystems which are not definitely compromised return to the condition of “ecological balance” once the causes of the disturbance have ended. Dynamic stability resulting from contrasting pressures and forces (e.g. production/consumption if biomass) are therefore restored within a given time (resilience). If interference factors remain constant, ecosystems (in general) have different “critical levels” (i.e. levels of degradation as a consequence to the pressure they are submitted to). They differ according to their intrinsic vulnerability and their sensitivity towards the different disturbance agents.
It is fundamental to establish different protection strategies (reclamation, depollution, renaturation, etc.), according to whether the transformation from balance conditions was caused by major events or by slight, extended, unperceivable “impulses”. When identifying the most efficient recovery action to adopt, with a cost-benefit analysis, it is also very important to determine the recovery capacity that each ecosystem has to return to its initial quality level after the cause of disturbance has ended. Each ecosystem has its own vulnerability towards specific stress (both natural and human), following certain causes of disturbance. It tends to have its own characteristic responses, representing an environmental element that best can gather the different features of a territory as a whole.