In the context of the new CAP, decoupling subsidies from production should incite farmers to reorganize their production systems, particularly through diversification opportunities. In this paper we focus our analysis on the conditions that could permit the development of extensive orchards by modelling mixed crop livestock farms, which incorporate orchards. A mathematical programming model is built to simulate various intensification levels characterizing different technical pathways within the different farm activities (cattle breeding, forage fields, arboriculture). This model also enables us to take into account some environmental indicators related to these pathways. Moreover, the method illustrates technical complementarities existing within the diversified systems, thanks to the joint production phenomena introduced into our analysis. We show how these complementarities can be integrated into the farmer's decision criteria.