An interdisciplinary team has applied the multi-agent system formalism to study shrub encroachment in the Biosphere Reserve on the isle of Ouessant. The main goals were (1) to understand vegetation dynamics, and (2) to represent how main agents, or actors view the dynamics of natural resources in relation to their own living practices. The management strategies established for each type of stakeholders were formalised and the impact of these strategies on biodiversity was analyzed at various temporal and spatial scales. Following a short description of the model, three aspects of the modelling process are discussed in more detail: the use of the chough (Pyrrhocorax pyrrhocorax) population as a representative variable for the interactions between stakeholders and territory, the use of nonmonetary economic indicators, and the ways that multi-disciplinary scientific knowledge can be integrated into the model. (C) 2009 Elsevier Ltd. All rights reserved.