Last update: 03/08/2004

Biodiversity

Defining biodiversity in a simple and comprehensive way, considering its many aspects, is not an easy task. Indeed, a strict and generally accepted definition is still to be found. The ecologist R.H. Whittaker (1972) simply stated that this concept can be applied to the abundance of species considered at various levels, such as the community, the areas studied by the biogeographer and the whole biosphere.
Ecologists use this term to refer to the variety of the current living beings on our planet, as a result of the complicated evolutionary processes of life over more than three billion years. According to Margalef (1968), the ecosystem can be considered a message that is transmitted through a certain channel with an adequate code (following the information theory). In his opinion, diversity is the result of the extent of information contained in the message. It involves measuring the number of elements, related to the abundance or rarity of the same. Based on this principle, some indexes on biological diversity have been proposed.
However, research on this issue has developed mainly on the relationships between ecosystems’ degree of maturity or stability and diversity itself. It is admitted that diversity depends on the relationships between the system’s various components. These tend to act as a bond or to establish feedback links.
In this way, diversity tends to be considered as the measurement of an ecosystem’s complexity. It measures the relationships existing between the various components of a biological assortment and therefore its complexity.
However, this concept has still not been sufficiently clarified and therefore cannot be applied in an undiscriminating way.
We need to keep in mind that an ecosystem’s functional aspects can be expressed in a specific way (i.e. energy exchanges, etc.) while for its structural aspects we do not have a clear and univocal system of references. Diversity measurements try to fill this gap, at least partly.
A modern interpretation, which is useful from an operational point of view, was given by E.O. Wilson (1992). According to him, biodiversity represents "the variety of ecosystems, which include both the communities of living organisms within their specific habitats and the physical conditions in which they live”.
The interest in biodiversity and its protection has grown so much that it became one of the three global emergencies identified during the United Nations Conference on Environment and Development that was held in Rio de Janeiro in 1992. We believe that an awareness of the intrinsic value of biological diversity and its ecological components can result from a growing understanding of the “environmental system” as a whole. In other words, a holistic approach of understanding nature makes us able to grasp both its structural and functional aspects. Conservation activities and a sustainable use of the natural heritage should thus take into account both the ecosystems’ conditions and variations and the policies, plans and sectorial and intersectorial policies that regulate the management of land.