Ecological Approaches

Ecology and natural resources dynamics

The scientific approach to natural resource dynamics involves the characterization of how the environment influences the abundance and availability of a given resource. From the ecological point of view, the environment is a collection of natural factors (physical, chemical, and biological) capable of affecting living organisms. Therefore, any factor that can be consumed or used by an organism is defined as a natural resource (Begon et al, 1990).

The "individual - environment - population" system (Barbault, 1992), which is at the heart of ecological thought, presents a multitude of intertwined interactions that can be grouped into one of two categories: interactions between organisms (competition, predation, mutualism, etc.), and interactions between organisms and their physical environment (the environmental "conditions").

In essence, ecology deals with the study of complex systems. A complex entity (Fogelman Soulié, 1991; Gell-Mann, 1994) is composed of different elements that interact and combine in a way that may not be obvious at first: the system's complexity is in the eye of the observer.

The idea that the concept of complexity is inseparable from perception is not neutral but depends on the scale of observation of the system under study. In ecology, there is no scale for observing all phenomena. Conventionally, the hierarchy of scales (Allen and Starr, 1982) refers to organizational levels: cell, organism, population, community, ecosystems, landscapes, biome, biosphere. One of the major issues in ecology is the ability to take into account the multiplicity of scales of study so that each of the phenomena studied at their specific levels can be integrated during a phase called "scale transfer".

Interactions between scales and disciplines

The research community is divided between those who are working on ethology and individual behaviour and those working on the ecology of the landscape and the structure or organization of space. Significant advances in ecology have been limited as a result.

Let us consider, for example, one of the common and relevant problems that occurs in managing renewable natural resources: estimating the risk of extinction of a species as a function of space fragmentation. In order to make an estimation, we need to know the global indicators for the spatial structuring of the landscape. However, we also need to know about the processes involved in animal migration and habitat selection, for example. These mechanisms can explain how the system functions. They should be taken into account in any model that seeks to give meaning to the indicators defined at a higher level.

Interdisciplinary combinations, which are essential for environmental sciences, are generally manifest on a global level. Landscape ecology (Forman and Gordon, 1986; Kareiva and Wennergren, 1995) is where geography and ecology come together. It is based on the principle that environmental problems generally go beyond the conventional limits of one or other subject and that their solutions require not only an understanding of the physical and ecological aspects of the ecosystems but also of the way they interact with political, economic, and social factors.

References

Allen T.F.H. et Starr T.B. 1982. Hierarchy: Perspectives for Ecological Complexity. University of Chicago Press, Chicago.

Barbault R. 1992. Ecologie des peuplements. Structure, dynamique et évolution. Masson, Paris.

Begon M., Harper J.L. et Townsend C.R. 1990. Ecology. Individuals, Populations and Communities. Blackwell, Cambridge.

Fogelman Soulié F. 1991. Les théories de la complexité autour de l'œuvre d'Henri Atlan. Seuil, Paris.

Forman R.T.T. et Gordon M. 1986. Landscape Ecology. John Wiley & Sons, New York.

Gell-Mann M. 1994. Le quark et le jaguar. Voyage au cœur du simple et du complexe. Albin Michel Sciences, Paris.

Kareiva P. et Wennergren U. 1995. Connecting landscape patterns to ecosystem and population processes. Nature, 373: 299-302.