3 présentations

• 
  10h45 - 11h15

  Mitigation of ecological economic vulnerabilities with adaptive controls

  • Abdoul Ahad Cisse, prés., Université de Guyane
  • Luc Doyen, GREThA Univ. of Bordeaux
  • Sophie Gourguet, AMURE - IFREMER
  • Olivier Thebaud, AMURE - IFREMER
  • Claire Macher, AMURE - IFREMER
  • Gilles Morandeau, LERAR - IFREMER
  • Nathalie Caill-Milly, LERAR - IFREMER

  Ecosystems and socio-ecosystems including fisheries have to face many ecological and economic uncertainties, vulnerabilities and risks. In this paper, a stochastic viability approach is proposed as operational framework for an adaptive decision-making mitigating these ecological economic vulnerabilities. An ecoviability scenario balancing ecological and economic objective is proposed. Two different strategies are compared: non-adaptive control (open loop) and adaptive control (closed loop or feedback control). The general framework is applied to the case of Bay of Biscay mixed fisheries. We show the gains of adaptive control approach both in term of spawning stock biomass, profits of fleets and ecoviability probability.

• 
  11h15 - 11h45

  Modelling the viability of livestock systems with target: the case of the French West Indies

  • Colombine Lesage, INRA UE PEYI
  • Valérie Angeon, INRA UR Ecodéveloppement
  • Samuel Bates, GRANEM, Université d'Angers
  • Pablo Andres-Domenech, prés., BETA AgroParisTech

  This article aims to analyze farmers strategic decisions in a context of persistent polluant formerly used in banana farming systems in the French West Indies. We wonder to what extent the adaptive capacity of livestock farming systems are viable. A theoretical viability model allows to identify the decision rules to be followed by the stakeholders of the livestock sector. Our results depict the diversity of rearing strategies according to the means, costs and duration of animal decontamination. It thus helps to define scenarios that are economically viable and socially acceptable considering a tighten regulation (decrease of the Maximum Residue Limit).

• 
  11h45 - 12h15

  The temporal dynamics of ecosystem services and their valuation: the case of agricultural soil quality

  • Marie-Hélène Durand, prés., IRD, UMR GRED, Montpellier and Lastre, Paris
  • Anna Desilles, Ensta-ParisTech, UMA, Palaiseau and Lastre, Paris
  • Patrick Saint-Pierre, Lastre, Paris

  Valuation of natural capital and of services provided by the ecosystems, is done by accounting technics or cost benefice analysis and used as management tool aimed at conservation. The spatial dynamics are taken into account by assessments of land use changes but the temporal dynamics are rarely considered. However, the value of ecosystem services varies depending on initial state of the ecosystem whose functions can be more or less degraded and for which time and cost of restoration or reproduction differ. Using a viability model of agricultural soil fertility management, we show that the relationship between the value of the ecosystem service provided by the soil quality (estimated by the best economic performance) and the time of restoration is not linear.