A model to explore which diversity is needed to design sustainable agricultural systems at the territorial level

Faced with changes related to climatic hazards or market variability, farmers deploy a variety of strategies to stabilize farm economic performances and reduce risk. One of the challenges faced by agricultural systems is how to reduce their sensitivity to these disturbances and maintain a certain level of production of goods and services. If diversity in crop and livestock activities in a farm has been shown to answer this challenge, at a higher scale, the growth of diversity and its benefits remain unclear. Using biotechnical models of existing farms within the territory of the Vallées de Duyes in the South of France, we propose to simulate various territorial configurations based on the assumption of diversity at farm and territorial scales and assess their expected sustainable properties. Based on the actual configuration of the referenced territory and composed of a set of specialized and mixed farms, two contrasted configurations are tested: from one side, a territory composed of specialized farms and, from the other side, a territory composed of mixed farms. The intrinsic diversity of individual farms impacts their performance and reveals that the resistance to economic shock varies according to the dependence on inputs and the use of rangelands. If mixed farms exhibit high values of diversity indicators for both land use and product provision, they also present high values for the majority of sustainable properties. At a higher scale, the specialized configuration shows the highest resistance to economic shock, but economic performances are lower than the referenced and specialized configurations. Here, we explore for the first time how several types of diversity indicators, both built within and between farms, could affect a set of sustainable properties of farms and territories. These new insights lead to a better understanding of how to balance performance at several scales and design sustainable Mediterranean farming systems.