Dans les territoires de montagne en Europe, les paysages évoluent sous l’effet d’une double dynamique : l’augmentation du couvert forestier et l’intensification des paysages agricoles. A partir d’un cas d’étude, le Mont Lozère, nous montrons comment ces deux dynamiques peuvent rentrer en tension, en explorant la question des choix sociaux liés aux dynamiques paysagères. Nous développons dans cette thèse un cadre conceptuel original, qui associe le concept de service écosystémique avec celui de l’état de référence, que nous avons mis en oeuvre par une démarche compréhensive et un dispositif de recherche-action. A travers l’étude des représentations, nous avons mis à jour un glissement de l’état de référence au sein des paysages agricoles, perçu différemment par les acteurs. Nous avons ensuite révélé les mécanismes sous-jacents aux choix liés aux dynamiques des paysages agricoles, ce qui nous a permis d’identifier un besoin de concertation autour de l’état de référence. Nous y avons répondu par une proposition concrète à travers un jeu de rôles, destiné à mettre les acteurs en situation d’apprentissages et à les accompagner vers des choix plus concertés. Notre contribution porte à la fois sur la question de la conciliation de différents objectifs dans les aires protégées, le rôle de l’état de référence dans la gouvernance des paysages et la plus-value scientifique et opérationnelle du concept de service écosystémique. / In mountain areas in Europe, landscapes evolve under the effects of the dual dynamics of both an increase of forest cover and the intensification of farming landscapes. Based on a case study, on the Mont Lozère we show how these two dynamics can be caught in tension by studying the question of the social choices linked to such landscape dynamics. In this thesis, we develop an original conceptual framework combining the concepts of ecosystem services and baseline references into a comprehensive and a research-action approach. The analysis of representations revealed a shifting baseline on the perception of farming landscapes, which are diversely perceived by stakeholders. We then describe the mechanisms underlying the choices related to farming landscape dynamics, and identify the need for dialogue around this baseline. We respond to this need with a proposition from role playing games that may help foster social learning and encourage more concerted choices. Our contribution addresses both the question of reconciliating different objectives in protected areas, the role of the baseline in landscape governance and the scientific and operational added-value of the concept of ecosystem services.

À venir / The customary regime of NRM in Bhutan faces greater challenges from economic development, rapid transformation of social values, local institutions and traditional perceptions on NR. Although Bhutan is projected rich in water resource for hydropower potentials, water for agriculture and domestic use is fast becoming scarcer and highly contested. As the water becomes scarce the people living in highlands are most severely affected. A detail diagnostic study of two communities, Lingmuteychu depedent of irrigated rice and Kengkhar depedent on dryland farming presents two situations of water resource issues. In Lingmuteychu the conflict of irrigation water sharing for cultivation of rice among seven villages has been inflicting restentment in all aspect of society. In contrary, in Kengkhar has been facing drinking water scarcity as the natural spring ponds dry, which forces people to walk from more than five hours to fetch water from the river. In these two sites Companion Modelling was applied to enhance understanding of water resource management dynamics and improve shared communication and learning to facilitate adaptative management dynamics and improve shared communication and learning to facilitate adaptative management strategies. The study provides as comparison of the process followerd in two sites with analysis of impacts and effects from the process. The research illustrates fow ComMod process help develop trust and and commitment in the conflicting community and pave pathways to develop social capital for adaptive management of water resource. The process was able to foster shared learning and co-construct collective actions which were implementable. The research also revealed the important role of the researchers in furthering and sustaining newly achieved cooperation. The ABMs provided an opportunity to re-create different water resource management strategies which could be used as options for the community. The research also demonstrates the feasibility of applying the ComMod approach in different fields of NRM.

Les Objectifs de Développement Durable visent d'ici 2030 un « accès pour tous à des services d'assainissement et d'hygiène adéquats, en mettant fin à la défécation à l'air libre ». Un service d'assainissement peut-être défini par ses composantes techniques et sociales, et leurs interactions. Dans l'optique de proposer des pistes d'améliorations des services d'assainissement en zone tropicale, les travaux de cette thèse ont porté à la fois sur des infrastructures de traitement et sur l'implication de l'ensemble des acteurs dans la définition du service. L'analyse croisée des contextes des départements d'outre-mer (DOM) français et du Sénégal a permis d'identifier des contraintes qui pèsent sur le secteur de l'assainissement en zone tropicale. Du point de vue des infrastructures de traitement, ces contraintes nous ont amenées à proposer des procédés issus de la famille des Filtres Plantés de Végétaux (FPV) comme solutions à priori pertinentes. Cette thèse présente leurs adaptations à la zone tropicale, en détaillant les choix retenus pour le dimensionnement, la conception des filtres et le choix des végétaux. Une centaine de campagnes de suivi ont été réalisées sur 7 stations pilotes en tailles réelles, à travers les 5 DOM. Les résultats montrent que malgré une plus grande compacité, le dimensionnement proposé permet de conserver des niveaux de traitement au moins comparables à ceux observés en climat tempéré. Compte tenu des contraintes climatiques et organisationnelles en milieu tropical, une analyse de leur résilience à des perturbations et de leur fiabilité de traitement a été réalisée par une étude statistique sur les données produites par l'autosurveillance réglementaire. Elle montre que les FPV sont également plus fiables que les procédés de traitement conventionnel les plus répandus pour les petites collectivités. Ce qui s'explique à la fois par la barrière physique que représente ces procédés de cultures fixées sur support fin ainsi que par des besoins en entretien plus réduits. Le deuxième axe de recherche part du constat d'un manque de concertation entre acteurs au moment de la planification de l'assainissement, étape qui préside à la construction du système d'assainissement. En particulier, les utilisateurs, leurs besoins et leurs contraintes sont très peu et mal pris en compte. La modélisation d'accompagnement pourrait permettre de créer à la fois un support (le modèle) permettant de discuter des choix techniques et de leurs conséquences, ainsi que le cadre dans lequel les différents acteurs pourraient échanger leurs points de vue et trouver un consensus soutenable. Un processus de modélisation d'accompagnement a été conçu et mis en place sur la planification de l'assainissement dans 2 zones (urbaine et rurale) du Sénégal. Il nécessitait, pour proposer des scénarios viables, d'intégrer une part non négligeable de connaissances expertes. Centré sur les populations, ce processus a permis la création d'un premier modèle générique sur l'accès à l'assainissement qui prend la forme d'un jeu de rôle. La pertinence de tels outils dans la caractérisation des besoins des usagers a été évaluée. Par ailleurs, l'attention a été portée sur l'acceptation par les usagers du service proposé et sa traduction en volonté de contribution / Sustainable Develoment Goals aim by 2030, to « achieve access to adequate and equitable sanitation and hygiene for all and end open defecation », by « using safely managed sanitation services ». Sanitation service can be defined by its technical and social components, and their interactions. This thesis focuses on both treatment infrastructures and involvement of all the stakeholders into service definition. Cross analysis of French Overseas Territories (FOT) and Senegal contexts, has identified common constraints that weigh on sanitation sector in tropical areas. From treatment infrastructure point of view, these constraints lead to suggest treatment wetlands systems and particularly French vertical-flow treatment wetland (FS-VFTW) to easier sludge managment, as a relevant solution. Their adaptation for tropical climate is the subjet of the first axis of our work. It aimed at defining their adaptation in terms of design, plant choices and defining the treatment wetlands type to implement according to outlet requirements. A hundred of 24h sampling campains were performed on 7 full scale demonstration plants, accross the 5 FOTs. Results show that despite more compacity, the proposed design allows maintaining performances at least similar to those observed in temperate climate. Due to climatic and organizational constraints inn tropical climate, a statistical analysis has been done to point out the resilience and reliability of the systems based on regulatory selfmonitoring data. It highlights the fact that FS-VFTWs are more reliable than most of the conventional treatment processes when applied for small size communities. Their physical barrier (filter) and their lower maintenance requirement explain this observation. The second axis of our research is based on an observed lack of consultation between stakeholders during the sanitation planning phase, which is responsible for the construction of the sanitation system. In particular, the users, their needs and their constraints are poorly and badly taken into account. Companion modeling approach could create both a support (the model) for discussing technical choices, as well as the framework within which the stakeholders could exchange points of view and find a sustainable consensus. Such a process has been developed and implemented for sanitation planning in 2 areas (urban and rural) of Senegal. Focused on household population, this process has led to create a generic model for sanitation access, embodied as a role playing game, which include a significant part of expert knowledge. The relevance of such tools in the characterization of user needs has been evaluated. In addition, attention was paid to users' acceptance of the proposed service and its translation into a willingness to contribute

The effectiveness of land sharing and land sparing (LS/LS) approaches to conservation in the face of rising agricultural demands has been widely debated. While numerous studies have investigated the LS/LS framework from an ecological lens (yield-biodiversity relationship) the relevance of the framework to real life depends on broader considerations. Some of the key caveats include: i) limited knowledge regarding the feasibility of interventions given diverse stakeholders’ interests, ii) the social acceptability (uptake) of these contrasting strategies to direct land users, and iii) limited knowledge regarding their impacts on individuals’ livelihoods and food security. Without considering these social science dimensions proponents of the framework risk an incomplete picture that is not grounded in local realities and can paradoxically force into opposition the very conservation and development interests they seek to reconcile. Using a Companion Modelling approach, which comprises the development of a role-playing game (RPG) and an agent-based model (ABM), this thesis addressed these caveats. The research was based in the Nilgiris of Western Ghats India, a tropical agricultural system at the forest frontier. The main findings show that through engaging local stakeholders in a participatory process, plausible land use strategies that align with their objectives could be identified. Stakeholders proposed three land use interventions. Two of them resemble a form of land sparing (‘monofunctional’ landscapes) on the farms: sparing land for Wildflower Meadows or Tree Plantations while increasing yield on the remaining land. The third intervention asks farmers to accept yield penalties for Intercropping more trees on their farms, a form of land sharing (‘integrated’ landscapes). In terms of decision-making regarding the adoption of these three interventions by direct land users, the study reveals several findings. Firstly there are three main types of motivations that influence farmers’ decision to adopt interventions, in order of importance: monetary benefits, pro-environmental motivations and social norms. Secondly, land use, the type of management preferred on the farm and whether land users accept trees on the farm or not are factors that influence what type of interventions is socially acceptable on individual farms. These factors have been detected in the in-depth household survey and also validated by the RPG. When assessing the adoption of the three interventions, ex ante their implementation, using an ABM, there are some important differences observed between the interventions. Wildflower Meadows is the intervention adopted by the largest number of households, whereas Intercropping is adopted across the largest area of land. Forest Plantations is significantly more unpopular than the other two interventions. The third line of investigation, about the outcomes of adoption, has important policy implications. Adding a socioeconomic dimension to the ecological one adds a level of complexity and creates a less straightforward choice between the LS/LS strategies. None of the three interventions can provide optimal outcomes for production, aspects of biodiversity conservation, livelihoods and food security. Each intervention has indicators that score better compared to the other two interventions. The findings demonstrate that the ecological focus of the LS/LS framework is insufficient to deal with real-world complexities and lends itself to overly simplistic policy prescriptions. More meaningful policies could be achieved when bridging natural and social sciences to better understand the merits and limitations of the LS/LS approaches.