MULTI-AGENT BASED MODELING OF THE TUNISIAN PASTORAL DYNAMIC Multi-level Organization Islem Henane 1,3 , Sameh Hadouaj 2,3 and Khaled Ghedira 1,3 1 Higher Institute of Management, Tunis, Tunisia 2 Faculty of Economic Sciences and Management, Nabeul, Tunisia 3 Laboratory of Strategy Optimisation of Information and Knowledge (SOIE), Tunis, Tunisia Keywords: Multi-agent Based Modeling, Complex System, Multi-level Organisation, Emergence, Multi-agent Platforms. Abstract: Pastoral systems in arid and semi arid areas are characterized by a continued deterioration. This degradation is the result of the mismanagement of resources in response to natural, economic and social mutations. These systems are considered as complex systems, given the large number of stakeholders in interaction and levels of granularity. To address this situation, analytical and systemic approaches are no longer adequate. In this paper, we propose a multi-agent based model of Tunisian pastoral dynamics taking into account the interaction dynamics of the different stakeholders and the different levels of granularity. The completion of this work is within the scope of the development of the Intelligent Decision Support System PASDES (Pastoral Strategies Definition System). PASDES aims to support pastoral strategic decision making in short and long terms. 1 INTRODUCTION Tunisian rangelands spread over almost one third of the country's area. Almost half of these rangelands are collectives. These figures reflect the importance of the pastoral activity. However, the Tunisian pastoral resources are in a continued deterioration. This deterioration is caused by the inappropriate strategies undertaken to address climate (high temperature, unstable precipitation) economical (increase in grain prices, global crisis) and social changes (privatization, competition over resources). The sustainability of the system is threatened. The pastoral system is a complex system characterised by a large number of interacting entities (plants, animals, shepherds, economic actors, state, etc) and different levels of granularity ( vegetation dynamics, animal dynamics, shepherds interactions and negotiations, etc). Thus, the study of such a system is conducted in the context of solving complex problems. In literature, three approaches are mainly used to study such a system. First, the analytical approach was adopted by economists. It focuses on the elementary study of the system components. For example, the study can be based on the maximizing of an objective function on a particular element of the system (Lalba, Zoundi and Tiendrebeogo, 2005) (Dutilly-Diane, 2006). This approach deals with one variable at a time which prevents the study of the overall system dynamics. Second, the systemic approach was adopted by ecologists. It is based on the study of the overall system behavior (Costanza, Wainger, Folke and Mäler, 1993) without taking into account the micro- dynamics. In this context, the emergence of global properties is evoked (Bergandi , 2000) (Oprisan and Oprisan, 2006). Third, the constructivist approach brings together the contributions of the analytical (micro-level study) approach as well as the systemic approach (macro- level study). It focuses on the study of micro-order interactions of different entities as well as the global system behavior. In this approach, we can distinguish the use of cellular automata (Soares-Filho, Cerqueira and Pennachin, 2002) and multi-agent systems. When using cellular automata, the environment is represented by a set of cells. The behavior of individuals is defined by a finite set of states, transition rules and neighbourhood relationship. However, cellular 254 Henane I., Hadouaj S. and Ghedira K.. MULTI-AGENT BASED MODELING OF THE TUNISIAN PASTORAL DYNAMIC - Multi-level Organization. DOI: 10.5220/0003832802540258 In Proceedings of the 4th International Conference on Agents and Artificial Intelligence (ICAART-2012), pages 254-258 ISBN: 978-989-8425-96-6 Copyright c  2012 SCITEPRESS (Science and Technology Publications, Lda.)