Résumé
In developing countries, biodiversity is often threatened by the development of agricultural production: it is often the case that natural habitats are destroyed by the conversion of forests, wetlands or natural pastures into arable land. There is a trade-off between revenues generated by agricultural production and services supplied by unspoilt natural capital (ecological services, possibility to develop biodiversity-related tourism activities). Whereas agricultural profits are private, biodiversity produces various types of benefits, some of them have global public good characteristics - they benefit all nations without exclusion and without rivalry - while others are regional inputs in the production functions of neighbouring countries. The purpose of this paper is to explore whether international income transfers can improve the global level of biodiversity and global social welfare by changing the relative contribution of biodiversity-protection and agricultural production in the national utility functions. We make the asumption that Southern countries are endowded with natural capital in the form of unspoilt biodiversity-rich land. They allocate optimally land and capital to two competing productive activities, agriculture et tourism. When transfers are organized from a northern biodiversity-poor country to southern biodiversity-rich countries, we show that Warr’s neutrality theorem collapses except under restrictive hypothesis concerning the characteristics of the tourism and agricultural production functions. We also demonstrate that Pareto-improvements can be obtained even with reductions in the level of biodiversity