Agent Based Modelling

... used to describe part of the ability of the whole population and to determine previous land ... The interaction between internal and external factors was defined by two indicators: the ... is adopted, agents can participate by planting new linear landscape elements, affecting the density ...

The decoupling of direct payments from production represents a substantial reform of the Common Agricultural Policy (CAP). Farmers are no longer required to produce commodities to be entitled to support but only to keep land in Good Environmental and Agricultural Condition. If output declines as a result, there is concern that landscape services produced jointly with commodities will also decline. The aim of this paper is to assess the long-term effects of the 2003 reform on farm structure, landscape mosaic and biodiversity for a sample of EU regions. Impacts are quantified using a spatial agent-based modelling approach by simulating agricultural development with links to indicators of landscape value. Our results demonstrate that eliminating the link between support payments and production has possible negative consequences for the landscape, but only under particular circumstances. It is shown that these effects could be offset by strengthening (Pillar II) agri-environmental schemes. Further the single payment scheme results in higher land rental prices which reduces its ability to achieve its goal of providing income security for farmers. Implications of these results for the direction of continued CAP reform are discussed.

Recent events have highlighted the importance of good models of crowds, however many existing crowd models are either computationally inefficient, or are missing a crucial human behaviour in crowds: local pushing. After discussing some essential aspects of force in crowds, and considering some existing models, we propose an efficient agent-based model of crowd evacuation that incorporates pushing forces and injuries. Basing our model on existing work, we extend this model to investigate force effects at different crowd densities. Analysis of our model shows significant effects of force on the crowd, as well as significant effects of crowd density when measuring the number of agents still trapped inside the space after a fixed time.

Agent-based modelling facilitates the implementation of tools for the analysis of social patterns. This comes from the fact that agent related concepts allow the representation of organizational and behavioural aspects of individuals in a society and their interactions. An agent can characterize an individual with capabilities to perceive and react to events in the environment, taking into account its mental state (beliefs, goals), and to interact with other agents in its social environment. There are already tools to perform agent-based social simulation but these are usually hard to use by social scientists, as they require a good expertise in computer programming. In order to cope with such difficulty, we propose the use of agent-based graphical modelling languages, which can help to specify social systems as multi-agent systems in a more convenient way. This is complemented with transformation tools to be able to analyse and derive emergent social behavioural patterns by using the capabilities of existing simulation platforms. In this way, this framework can facilitate the specification and analysis of complex behavioural patterns that may emerge in social systems.

In rural regions, land use changes (LUC) are often the result of the decision-making of individual farmers. To influence this decision-making, compulsory and voluntary mechanisms are implemented. However, farmers’ decision-making is a heterogeneous process that depends on their ability and willingness to take certain decisions. Discrepancies between farmers’ ability and willingness and the design of voluntary mechanisms occur frequently. This makes it necessary to understand how farmers’ participation in these mechanisms can affect LUC. The aim of this paper was to demonstrate an agent-based approach to analyse and explore how voluntary mechanisms can influence LUC processes in rural regions. This approach was applied to a rural region in Australia, where clearing of native vegetation has occurred for agricultural development. Historical land cover data and semi-structured interviews were used to parameterise an agent-based model. Factors that influence farmers’ ability and willingness to participate in these mechanisms were identified. Three scenarios were simulated with the model to explore how the implementation of different voluntary mechanisms can affect the landscape structure of the region. This paper identifies how the diversity of farmers’ decision-making can influence the landscape structure in the region. The advantages and limitations of an agent-based approach in relation to LUC research and policy are discussed.

In the frame of using models to promote dialogue among stakeholders, we are interested in modelling representations as a mean to share viewpoints and opinions. A first trend for modelling representations uses socio-cognitive theories as frameworks for modelling. This article proposes a different approach combining Knowledge Engineering elicitation techniques and Agent Based Modelling. The use of elicitation techniques provides a methodological framework to capture representations directly from stakeholders’ discourse. Agent Based Modelling serves as a modelling structure which enables managing representations’ heterogeneity and conflicting opinions. The proposed methodology is detailed and applied to farmers’ representations of runoff and erosion in south of France. To achieve the construction of a running model of the interviewees’ shared representation, it was necessary to implement theoretical data supplementing the elicited information. We argue that companion modelling approach can help sharing and discussing those non-elicited information with stakeholders.