We show that whether intensive or extensive farming is most beneficial to biodiversity depends on the equilibrium of agricultural markets. With higher production costs, extensive farming tends to be more beneficial to biodiversity than intensive farming, except when there is a very high degree of convexity between biodiversity and yield. Extensive farming is detrimental to consumers while its effect on agricultural producers is indeterminate. It has no straightforward effect on food security, but could decrease the pressure on protected areas. Additional demand f reinforces the preference for extensive farming, especially in the case of animal feed. (Résumé auteur)