This paper presents a generic, agent-based model that simulates the dynamics of crop varietal diversity at the village level in Mali under different socio-economic, environmental and policy scenarios. The model is designed to integrate social, economic, environmental, and policy factors . A participatory approach with scientists, farmers and policy makers has been implemented to achieve this goal. This approach combines role playing games with agent-based modelling. A set of scenarios are elaborated to evaluate the possible impacts of policy interventions and climate change on agrobiodiversity dynamics. Simulations showed how farmers manage crop varietal diversity to cope with the local climate variability for their annual crop production. The portfolio of varieties increases under stable and good climate condition and decrease under less favourable and variable climate conditions. In addition, depending on the climate condition, farmers allocate preferentially land to varieties with higher yields.