Application of the ecosystem service concept at a small-scale: The cases of coralligenous habitats in the North-western Mediterranean SeaJournal articleLaure Thierry de d'Avray, Dominique Ami, Anne Chenuil, Romain David and Jean-Pierre Féral, Marine Pollution Bulletin, Volume 138, pp. 160-170, 2019

The understanding of ecosystem services is essential to support sustainable use and preservation of ecosystems. Coralligenous habitats, main contributors of the Mediterranean marine biodiversity, are yet understudied in term of services provided. This study presents an original small-scale approach to investigate the services provided by coralligenous habitats of a French study area consisting of two marine sites (Marseille and Port-Cros sites) in order to cover two contrasted anthropogenic pressure despite the small-scale. Our results are based on the opinions of 43 experts who ranked 15 services in terms of existence and level of importance for human well-being: supporting ecological functions were considered the most important, then provisioning and cultural services. Regulating services were considered uncertain due to a lack of knowledge. The small-scale approach highlighted a need for a referential frame to determine the existence of services (e.g. geographical and temporal scales, benefits and beneficiaries levels).

The environmental and socio-political stakes of counting users within protected natural areas: an interdisciplinary study using interval photographyJournal articleCécilia Claeys, Sandrine Ruitton, Noemie Frachon, Patrick Bonhomme, Mireille Harmelin, Dominique Ami and Carole Barthélémy, Visual Methodologies, Volume 5, Issue 2, pp. 8-20, 2018

This article offers a reflexive presentation of an interdisciplinary case study involving environmental sociology and marine biology. The creation of the Calanques National Park (April 2012), next to Marseille, the second largest city in France, has fuelled debate over the increasing impact of widespread leisure activities on the conservation of biodiversity. Given this, our research programme has developed visual interdisciplinary methods and critically analysed the notion of overuse. This paper presents a case study of Sormiou Bay, a natural anchorage site whose seabed is covered in a meadow of protected seagrass, Posidonia oceanica. Our research involved qualitative and quantitative field surveys and interval photography over a 19-month period, as well as the use of historical aerial photographs. Three main findings are presented here. First, our analysis reveals that a gap exists between actual and perceived levels of use, and this is exacerbated by a scale effect. Secondly, we point out the social and cultural factors, as well as the political context underpinning users’ discourse regarding (over)use of the Calanques. Lastly, we underscore the gap between the environmental awareness of boaters, their actual behaviour and their impact on Posidonia oceanica meadows.

Un diagnostic de gouvernance basé sur le discours des acteurs : le cas du littoral marseillais « côté mer » (Marseille, France)Journal articleDominique Ami, Juliette Rouchier and Stéphane Calandra, VertigO : La Revue Électronique en Sciences de l'Environnement, Volume 18, Issue 2, 2018

Nous étudions ici le discours que certains acteurs du littoral marseillais (des usagers, des élus et des gestionnaires) ont de la gouvernance de la zone, en nous penchant en particulier sur l’institution (l’ensemble des règles) telle qu’elle est perçue et comment les divers acteurs sont vus comme plus ou moins légitimes. Nous utilisons pour cela le cadre d’analyse Institutional Analysis and Development construit par Elinor Ostrom pour analyser des entretiens semi-directifs menés en 2013. Nous avons en particulier identifié la description des usages, des acteurs, des conflits et des nuisances, ainsi que la répartition des rôles de définition des règles et d’autorité. Nous notons plusieurs éléments importants : les acteurs partagent un objectif affiché de protection du littoral identifié comme un espace très fréquenté, fragile, entre terre et mer, ils identifient un acteur central légitime (le Parc national des Calanques, pourtant à peine en fonction à l’époque) comme meneur de la gouvernance, et définissent également des usagers extérieurs non légitimes (les touristes, les pollueurs) comme acteurs qui ne partagent pas les objectifs de locaux. Les règles opérationnelles sont relativement peu remises en cause alors qu’il existe une certaine incompréhension et même une confusion pour les règles de choix collectifs et les règles constitutionnelles. Ces dernières, qui permettent de penser la dynamique des institutions semblent avoir disparu depuis la création du Parc national, ce qui signale une gouvernance imparfaite, mais permet aussi d’indiquer un chemin pour l’améliorer.

When do social cues and scientific information affect stated preferences? Insights from an experiment on air pollutionJournal articleDominique Ami, Frédéric Aprahamian, Olivier Chanel and Stéphane Luchini, Journal of Choice Modelling, Volume 29, Issue C, pp. 33-46, 2018

Stated preference surveys are usually carried out in one session, without any follow-up interview after respondents have had the opportunity to experience the public goods or policies they were asked to value. Consequently, a stated preference survey needs to be designed so as to provide respondents with all the relevant information, and to help them process this information so they can perform the valuation exercise properly. In this paper, we study experimentally an elicitation procedure in which respondents are provided with a sequence of different types of information (social cues and objective information) that allows them to sequentially revise their willingness-to-pay (WTP) values. Our experiment was carried out in large groups using an electronic voting system which allows us to construct social cues in real time. To analyse the data, we developed an anchoring-type structural model that allows us to estimate the direct effect (at the current round) and the indirect effect (on subsequent rounds) of information. Our results shed new light on the interacted effect of social cues and objective information: social cues have little or no direct effect on WTP values but they have a strong indirect effect on how respondents process scientific information. Social cues have the most noticeable effect on respondents who initially report a WTP below the group average but only after receiving additional objective information about the valuation task. We suggest that the construction and the provision of social cues should be added to the list of tools and controls for stated preference methods.

Stated Preferences and Decision-Making: Three Applications to HealthJournal articleDominique Ami, Frédéric Aprahamian and Stéphane Luchini, Revue Économique, Volume 68, Issue 3, pp. 327-333, 2017


Integration of Path-Dependency in a Simple Learning Model: The Case of Marine ResourcesJournal articleNarine Udumyan, Juliette Rouchier and Dominique Ami, Computational Economics, Volume 43, Issue 2, pp. 199-231, 2014

Overexploitation of renewable resources, and more particularly fisheries, is often driven by the lack of information about the state and dynamics of the resource. A solution to this problem stemming from the resource users is proposed in this paper. We use an agent-based model composed of a bio-economic model of Gordon-Schaefer where agents make choices following a very simple learning model. We modify the Roth-Erev learning model so that agents explain their profit not only by current action but also by past action. This modification radically changes the dynamics of the resource use, which turns out to be sustainable. Copyright Springer Science+Business Media New York 2014

Willingness to pay of committed citizens: A field experimentJournal articleDominique Ami, Frédéric Aprahamian, Olivier Chanel, Robert-Vincent Joule and Stéphane Luchini, Ecological Economics, Volume 105, Issue C, pp. 31-39, 2014

In this paper, we propose a behavioral approach to determine the extent to which the consumer/citizen distinction affects interpretations of monetary values in stated preferences methods. We perform a field experiment dealing with air pollution, where some (randomly selected) subjects are given the opportunity to behave politically by signing a petition for environmental protection prior to stating their private preferences in a standard contingent valuation exercise. We show that signing has the potential to influence respondents' willingness to pay values. Results indicate that even market-like situations are not immune to citizen behavior.

Comment les individus valorisent-ils les décès associés à la pollution atmosphérique ? Une comparaison de trois scénarios hypothétiquesJournal articleDominique Ami, Frédéric Aprahamian, Olivier Chanel and Stéphane Luchini, Économie et Statistique, Volume 460-461, Issue 1, pp. 107-128, 2013

[fr] La valorisation économique d’une diminution du risque de mortalité recourt de plus en plus fréquemment aux techniques d’évaluation contingente. Celles‑ci consistent à interroger un échantillon d’individus sur leur «consentement à payer » (CAP) pour réduire ce risque à partir de scénarios hypothétiques. Les CAP dépendent toutefois de nombreux facteurs et notamment de la nature du risque sous‑jacent et du scénario proposé pour le réduire. Cet article s’intéresse à la diminution du risque de mortalité associé à une exposition à la pollution atmosphérique et teste l’effet d’une modification du contexte d’évaluation hypothétique à travers trois scénarios : un nouveau médicament, un déménagement et de nouvelles réglementations. Pour analyser les CAP déclarés dans les différents scénarios, nous définissons un cadre d’analyse unifié, théorique puis économétrique, qui prend en compte les préférences des participants pour le présent, ainsi que celles des autres membres du ménage. Deux résultats en découlent. Les taux d’actualisation implicites estimés, spécifiques à chacun des scénarios hypothétiques, se révèlent significativement différents. De l’ordre de 7 % pour le scénario «déménagement » , ils sont respectivement de 24 % et 26 % pour les scénarios «médicament » et «réglementation » . Il en résulte des «valeurs d’évitement d’un décès » (VED) moyennes très différentes entre le scénario «déménagement » (801 000) d’une part, et les scénarios «médicament » (299 000) et «réglementation » (252 000) d’autre part.
[en] The economic value placed on a reduction in the risk of mortality relies more and more frequently on contingent assessment techniques. These consist in questioning a sample of individuals on their “ willingness to pay” (WTP) in order to reduce this risk, on the basis of hypothetical scenarios. These WTP nevertheless depend on many factors, especially the nature of the underlying risk and the scenario proposed to reduce it. This article deals with reducing the risk of mortality associated with exposure to atmospheric pollution and tests the effect of a change in the hypothetical context of assessment through three scenarios : a new drug, a house move and new regulations. To analyse the “ willingness to pay” stated in the different scenarios, we define a unified, theoretical then econometric framework of analysis, taking into account the preferences of the participants at present, and also those of other household members. There are two main results. The estimated implicit updating rates, specific to each hypothetical scenario, were seen to differ significantly. They were about 7% for the “ move” scenario and 24% and 26% for the “ drugs” and “ regulations” scenarios respectively. Results showed that the average “ values set for avoiding death” differed greatly between the “ move” scenario (801,000) on the one hand, and the “ drugs” (299,000) and “ regulations” (252,000) scenarios on the other hand.

A Test of Cheap Talk in Different Hypothetical Contexts: The Case of Air PollutionJournal articleDominique Ami, Frédéric Aprahamian, Olivier Chanel and Stéphane Luchini, Environmental & Resource Economics, Volume 50, Issue 1, pp. 111-130, 2011

We explore the influence of a neutral cheap talk script in three typical scenarios used in the CV literature devoted to the valuation of air pollution effects. We show that cheap talk has a differentiated effect depending on the scenario implemented. It decreases protest responses with no effect on WTP values in the scenario based on a new drug. When a move to a less polluted city is involved, it has no effect on protest responses but decreases WTP values. Surprisingly, cheap talk increases protest responses but decreases WTP values when new regional air pollution regulations are at stake.

Vers un renouveau encore fragile des méthodes de préférences déclarées (Commentaire sur l'article de Bénédicte Rulleau, Jeoffrey Dehez et Patrick Point "Approche multidimensionnelle de la valeur économique des loisirs de natureJournal articleDominique Ami and Olivier Chanel, Économie et Statistique, Issue 421, pp. 47-51, 2009