Description:
On the value of biodiversity. Biodiversity has become a major global issue. The 1992 Earth summit at Rio recommanded discussions on approaches to safeguard biodiversity and to implement national conservation strategies (CNUED, 1993). Such preservation programs generate benefits but are costly. Planners must be given quantitative elements to appreciate these benefits and costs. Economists are then in front of a classical micro-economic problematic : they have to establish the relation between the level of biodiversity and the social value of the services floivs it generates. Therefore they use a surplus analysis. This paper shoivs why such a valuation exercise is difficult for economists : the available frame for such an analysis in the context of the biodiversity preservation is not sufficient. This insufficiency results firstly from the complexity of the ressource. The paper shows that there is no unique and precise definition of the biodiversity. The definition of the biologists and the definition of the ecologists differ. The correspondance with the economic good biodiversity is then difficult. This insufficiency results secondly from the non-familiarity of the individuals with the good to value. Because valuation must take into account the totality of the benefits (use and non-use benefits) that biodiversity preservation may generate, data issued from hypothetical markets have to be used. On these hypothetical markets, people are directly intervieived on the value they give to biodiversity. But the non-familiarity of the individuals ivith the good to value (a program of biodiversity preservation) often implies that the obtained values are biased. Individuals are not accustomed to consider a biodiversity preservation program in their program of utility maximization. This article proceeds by a revieiv of the existing studies. The most remarquable ones are then developed to illustrate the above aspects.
La préservation de la diversité biologique, ou biodiversité, est devenue une priorité publique pour les Etats-membres de l'ONU. Les recherches se donnent pour objectif l'identification des bénéfices et coûts de ces programmes. Une telle analyse s'appuie sur une problématique de micro-économie classique. Il s'agit d'établir la relation entre le niveau de biodiversité et la valeur sociale du flux de services rendus par ce niveau. Le cadre dont disposent les économistes pour procéder à une telle évaluation n'est cependant pas suffisant. La revue des études présentée dans cet article met en évidence cette insuffisance en insistant sur deux problèmes spécifiques à la ressource : la non-familiarité et la complexité du bien pour les individus.