Economic rationalization of plant genetic resources conservation.

Summary This thesis analyzes the economic consequences of the erosion of biodiversity and more particularly of plant genetic resources. The observed erosion justifies the setting up of in-situ or ex-situ conservatories (seed banks). Our attention was focused on this second type of conservation which is the preferred mode to conserve gvr. The objective of this work is to define a conservation organization that is compatible with the maximization of collective utility. To answer these questions, we have organized this work into three parts: 1. We present an introduction to the current organization of conservation. The triplet cost benefit risk of the different techniques appears crucial in the decision making, thus imposing an approach in terms of choice in an uncertain future. 2. This leads us to deepen the "option value" models developed by C. Henry in 1974 and to propose a more general model. Thus, it is proven that the concept of irreversibility traditionally used rarely corresponds to the real environment of the decision maker and can lead to a non-rational decision. 3. These different results led us to build a sequential decision model applied to the conservation of rgv. By simulations, we have defined the intervals favorable to conservation and the sensitivity of the model to the parameters.