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Featured researches published by Pierre Mazzega.


Ecology | 2001

OSCILLATORY DYNAMICS AND SPATIAL SCALE: THE ROLE OF NOISE AND UNRESOLVED PATTERN

Mercedes Pascual; Pierre Mazzega; Simon A. Levin

Predator-prey and other nonlinear ecological interactions often lead to os- cillatory dynamics in temporal systems and in spatial systems when the rates of movement are large, so that individuals are effectively well mixed and space becomes unimportant. When individuals are not well mixed, however, properties of fluctuations in population densities, and in particular their amplitudes, are known to vary with the spatial scale at which the system is observed. We investigate the relationship among dynamics at different spatial scales with an individual-based predator-prey model that is stochastic and nonlinear. Results elucidate the role of spatial pattern and individual variability in the dynamics of densities. We show that spatial patterns in this system reduce the per capita rates of predation and prey growth but preserve functional forms. The functional forms remain those one would expect in a well-mixed system in which individuals interact according to mean population densities, but with modified parameters. This similarity of the functional forms allows us to approximate accurately the long-term dynamics of the spatial system at large scales with a temporal predator-prey model with only two variables, a simple system of ordinary differential equations of the type ecologists have been using for a long time. This approximation provides an explanation for the stabilizing role of space, the decrease in the amplitude of fluctuations from the well-mixed to the limited-movement case. We also provide an explanation for the previously described aperiodic dynamics of densities at intermediate spatial scales. These irregular cycles result from the interplay of demographic noise with decaying oscillations, where the decay of the cycles is due to the spatial patterns. It is indeed possible to capture essential properties of these cycles, including their apparent sensitivity to initial conditions, with a model that follows individuals but parameterizes their spatial interactions in a simple way, using again the similarity of func- tional forms and the modified parameters. Thus, demographic noise appears essential at a spatial scale previously chosen for the high degree of determinism in the dynamics. Our results illustrate a semi-empirical approach to simplify and to scale spatial ecological systems that are oscillatory from individual or local-scale to large-scale dynamics.


multi agent systems and agent based simulation | 2013

The MAELIA Multi-Agent Platform for Integrated Analysis of Interactions Between Agricultural Land-Use and Low-Water Management Strategies

Benoit Gaudou; Christophe Sibertin-Blanc; Olivier Therond; Frédéric Amblard; Yves Auda; Jean-Paul Arcangeli; Maud Balestrat; Marie-Hélène Charron-Moirez; Etienne Gondet; Yi Hong; Romain Lardy; Thomas Louail; Eunate Mayor; David Panzoli; Sabine Sauvage; José-Miguel Sánchez-Pérez; Patrick Taillandier; Nguyen Van Bai; Maroussia Vavasseur; Pierre Mazzega

The MAELIA project is developing an agent-based modeling and simulation platform to study the environmental, economic and social impacts of various regulations regarding water use and water management in combination with climate change. It is applied to the case of the French Adour-Garonne Basin, which is the most concerned in France by water scarcity during the low-water period. An integrated approach has been chosen to model this social-ecological system: the model combines spatiotemporal models of ecologic (e.g. rainfall and temperature changes, water flow and plant growth) and socio-economic (e.g. farmer decision-making process, management of low-water flow, demography, land use and land cover changes) processes and sub-models of cognitive sharing among agents (e.g. weather forecast, normative constraints on behaviors)


international conference on legal knowledge and information systems | 2007

Codification, Law Article and Graphs

Danièle Bourcier; Pierre Mazzega


international conference on artificial intelligence and law | 2007

Toward measures of complexity in legal systems

Danièle Bourcier; Pierre Mazzega


International Workshop on Multi-Agent-Based Simulation - MABS 2013 | 2013

The MAELIA multi-agent platform for integrated assessment of low-water management issues

Benoit Gaudou; Christophe Sibertin-Blanc; Olivier Therond; Frédéric Amblard; Yves Auda; Jean-Paul Arcangeli; Maud Balestrat; Marie-Hélène Charron-Moirez; Etienne Gondet; Yi Hong; Romain Lardy; Thomas Louail; Eunate Mayor; David Panzoli; Sabine Sauvage; José-Miguel Sánchez-Pérez; Patrick Taillandier; Van Bai Nguyen; Maroussia Vavasseur; Pierre Mazzega


7th International Environmental Modelling and Software Society (iEMSs 2014) | 2014

Integrated modelling of social-ecological systems: The MAELIA high-resolution multi-agent platform to deal with water scarcity problems

Olivier Therond; Christophe Sibertin-Blanc; Romain Lardy; Benoit Gaudou; Maud Balestrat; Yi Hong; Thomas Louail; Van Bai Nguyen; David Panzoli; José-Miguel Sánchez-Pérez; Sabine Sauvage; Patrick Taillandier; Maroussia Vavasseur; Pierre Mazzega


International Journal of Applied Earth Observation and Geoinformation | 2013

Discharge and suspended sediment flux estimated along the mainstream of the Amazon and the Madeira Rivers (from in situ and MODIS Satellite Data)

S. Mangiarotti; Jean-Michel Martinez; Marie-Paule Bonnet; Diogo Costa Buarque; Naziano Filizola; Pierre Mazzega


Theoretical Population Biology | 2003

Quasicycles revisited: apparent sensitivity to initial conditions

Mercedes Pascual; Pierre Mazzega


Archive | 2014

Calibration of simulation platforms including highly interweaved processes: the MAELIA multi-agent platform

Romain Lardy; Pierre Mazzega; Christophe Sibertin-Blanc; Yves Auda; José-Miguel Sánchez-Pérez; Sabine Sauvage; Olivier Therond


Archive | 2012

Politiques Publiques, Systèmes Complexes

Danièle Bourcier; Romain Boulet; Pierre Mazzega

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Olivier Therond

Institut national de la recherche agronomique

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Maud Balestrat

Institut national de la recherche agronomique

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Romain Lardy

Institut national de la recherche agronomique

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