Emergence of a strategic complementarity between agriculture and biodiversity in territories with high environmental value. The example of the Camargue.

Summary In this thesis, we examine the emergence of a strategic complementarity between agriculture and biodiversity in territories with high environmental value. We study the example of the Camargue, a wetland of international interest, where the challenge is to reconcile agriculture and environmental protection. First, we analyze the Camargue context, emphasizing the ambivalent relationship between agriculture and biodiversity. Insofar as the future reform of the CAP will call into question the conditions of granting of these aids, as much as their global volume, the development of the Camargue rice-growing passes in the long run by its association with an image of wild and natural land. This strategic complementarity may allow future public policies to be designed and justify the maintenance of aid to Camargue rice growing, through its contribution to the sustainable management of biodiversity. We then examine the economic conditions for the emergence of organic rice production in this particular context. The market conditions, and more precisely the presence of imperfect competition, characterized by the concentration of the supply of inputs (herbicides and seeds) in a small number of suppliers. Their adaptation strategies to the development of organic farming practices are constrained by market conditions and limited to the quantities offered. We investigate under which conditions a strategic equilibrium exists, and exclude extreme equilibria (dominant/excluded organic rice). Our results place varietal supply strategies at the heart of these strategic interactions, which is why we extend this strategic approach by studying the economic determinants of varietal diversity in Camargue rice farms. This confirms the importance of niche strategies, and highlights the role of market opportunities and networks in farmers' choice of cultivar portfolio, beyond the structural constraints of the farm. Finally, a "choice experiments" type of survey reveals the influence of collective norms in the preferences of Camargue rice farmers for the production technologies at their disposal. The results of this empirical study show that a large majority of producers could adopt technologies without chemical inputs, provided that they are accompanied by financial compensation equivalent to that currently granted unconditionally under the CAP. Beyond the case study, the thesis provides useful lessons for the design of public policies capable of reconciling economic efficiency and sustainable development. It is also a contribution to the reflection on the integrated multi-actor management of agriculture and biodiversity on the scale of a territory with high environmental value.