Concept de Modèle Ecologique pour la Zone Humide Alaotra

The wet zone Alaotra consists of the largest lake of Madagascar with about 20,000 ha of open - water and up to 23,000 ha of marshes. This wet zone is unique by the presence of an endemic fauna, and its marshes consist of a monospecific vegetation. The local communities directly depend on this wet zone with fishing and agriculture being an integral part of the region’s economy. Consequently, various anthropological pressures such as burning of the vegetation, over - fishing, pollution of the lake by the use of weed - killers, and sedimentation of the watersheds due to heavy erosions of the surrounding hills, negatively impact on this ecosystem. The wet zone Alaotra has been classified as an official Ramsar wetland site since 2003 and also as a SAPM protected area in January 2007 because of its ecological importance and its various threats to this ecosystem. The objective of this article is to present and describe the ecological model, which consists of the identification of the various ecological entities as well as their interdependence, in order to justify the wetlands classification as both a Ramsar and a New Protected Area site. The model has been adopted from Ogden (2005), and its ecological entities integrated in the conceptual model are derived from various research works conducted on the wet zone Alaotra. The model will be critically important in convincing the local authorities as well as the local communities to work together with the researchers, in order to implement the best conservation practices and ensure the sustainable management of the wet zone Alaotra

Etude des écarts à l'équilibre thermique dans les plasmas d'arc

L'hypothèse de l'équilibre thermodynamique local (ETL) est souvent considérée dans l'étude des plasmas thermiques, bien qu'elle ne soit légitime que pour la description de la colonne du plasma. En effet l'équipartition de l'énergie peut être mise à défaut dans certaines zones du plasma telles que les zones périphériques ou le proche voisinage des électrodes. En vue de mettre en place une modélisation auto cohérente, une représentation globale du cœur du plasma et des zones en déséquilibre est nécessaire. Dans cette optique, ce travail décrit la mise en place d'un modèle hors ETL à deux températures (2T) sur une configuration " d'arc libre " où le milieu est décrit par deux équations de l'énergie : l'une pour les électrons Te, et l'autre pour les particules lourdes Th. Ces deux équations sont couplées par un terme d'échange d'énergie Eeh. Dans un premier temps la mise en place des données de base du plasma est réalisée. Cette partie englobe le calcul de la composition hors équilibre thermique d'un plasma d'argon. A partir des compositions hors ETL, les coefficients de transport, les propriétés thermodynamiques, et le terme d'échange d'énergie peuvent être déterminés. L'évolution de ces propriétés est présentée en fonction de Te et du rapport Te/Th. Un modèle unidimensionnel d'arc stabilisé par paroi est ensuite mis en place. La configuration simplifiée du modèle permet d'étudier le déséquilibre thermique entre la température électronique et la température des particules lourdes. Une étude paramétrique est réalisée et les résultats commentés. Dans une dernière partie l'étude est étendue à un cas bidimensionnel sur une configuration d'Arc libre dans l'Argon. La mise en place des équations de l'énergie pour la description à deux températures est détaillée. Une attention particulière est portée sur la programmation en vue d'une résolution via le logiciel @Fluent. Les résultats des modèles ETL et hors ETL sont confrontés à des résultats expérimentaux issus de la littérature. Une étude est alors réalisée au travers du paramètre intensité du courant.The assumption of local thermodynamic equilibrium (LTE) is often considered in the study of thermal plasmas, although it is legitimate only to describe the column of plasma. Indeed, the equipartition of energy may fail in some areas of the plasma such as peripheral zones or areas in the vicinity of the electrodes. In order to develop a self consistent model, a global representation of the plasma heart and areas in thermal imbalance is required. From this perspective, this work describes the development of a non-LTE two-temperature model on a "free arc" configuration where the gas is described by two energy equations: that of electrons Te and that of heavy particles Th. Those two equations are coupled by an energy exchange term Eeh. At first, the establishment of the plasma baseline data is performed. This section includes the calculation of non-equilibrium argon plasma composition. From the NETL compositions, the transport coefficients, the thermodynamic properties and the energy exchange term can be determined. The evolution of those properties according to Te and the ratio Te/Th is presented. A one-dimensional model of wall-stabilized arc is carried out. The simplified configuration of the model allows studying the thermal imbalance between the electrons temperature and the temperature of heavy particles. A parametric study is performed and the results are discussed. In a last section, the study is extended to a two-dimensional cas on a free argon arc configuration. The setting up of energy equations for the two-temperature description is detailed. Particular attention is paid to programming for resolution through the software @Fluent. Results of the LTE and NLTE models are confronted to experiment results from literature. A study is then conducted through the parameter current intensity

Inventaire et typologie floristique des milieux lentiques dans le district de Vohipeno

L’écologie des macrophytes (plantes aquatiques visibles à l’œil nu) est peu étudiée à Madagascar. L’écosystème aquatique du district de Vohipeno  (Région Vatovavy Fitovinany) n’a fait l’objet d’étude que pendant la période coloniale de 1921 à 1936. Les objectifs de cette étude sont d’améliorer la connaissance sur les macrophytes et d’établir une typologie floristique des zones humides malgaches. Au total, 43 espèces réparties entre 34  genres et 19 familles ont été recensées. Les valeurs de l’indice de Shannon Weaver ont montré une faible diversité mais une distribution hétérogène. L’analyse du coefficient de similarité de Sorensen a révélé une ressemblance entre certains sites. L’Analyse Factorielle des  Correspondances (AFC) met en exergue quatre groupements de végétaux appuyés par la Classification Ascendante Hiérarchique (CAH). The ecology of macrophytes (aquatic plants) has not been extensively studied in Madagascar. The aquatic ecosystem of the district of Vohipeno (Vatovavy Fitovinany) was last studied during the colonial period 1921 to 1936. The objectives of this study were to improve the knowledge on macrophytes and to make a floristic typology of Malagasy wetlands. In total 43 species distributed between 34 genera and 19 families were  recorded. The Shannon Weaver index showed low diversity but a heterogeneous distribution. The Sorensen coefficient analysis revealed  resemblances between certain sites. Correspondence Analysis (CA) highlighted four vegetation groups and was supported by Hierarchical  Clustering (HCPC)

Delivering Climate-Development Co-Benefits through Multi-Stakeholder Forestry Projects in Madagascar: Opportunities and Challenges

This paper explores multi-stakeholder perspectives on the extent to which forestry projects that pursue ecological restoration and rehabilitation in Madagascar engage with local communities and can co-deliver climate-development benefits. Drawing on mixed methods (policy analysis, semi-structured interviews, participatory site visits and focus groups) in two different forestry contexts, we show that by strengthening access to capital availability, projects can enhance local adaptive capacity and mitigation and deliver local development. We show that active consideration of ecological conservation and action plans early in project design and implementation can co-develop and support monitoring and reporting systems, needed to progress towards integrated climate-compatible development approaches. Climate mitigation benefits remain poorly quantified due to limited interest in, and low capacity to generate, carbon revenues. Monitoring alone does not ensure carbon benefits will materialize, and this research stresses that institutional considerations and strengthened engagement and cooperation between practitioners and communities are key in achieving both climate mitigation and community development impacts. Multiple benefits can be fostered by aligning objectives of multiple landscape actors (i.e., community needs and project developers) and by systematically linking project deliverables, outputs, outcomes and impacts over time, grounded in a theory of change focused on ensuring community buy-in and planning for delivery of tangible benefits

Method for evaluating perceptions about animals and plants among the inhabitants of the northwestern coastal zone of Madagascar

The evaluation of global perceptions about animal and plant species by villagers living in protected area including fragmented dry forests has been conducted in the northwestern coastal zone of Madagascar. The methodology used in field conditions is presented and discussed in relation to possible integration of the results into localized botanical and zoological surveys, which have been conducted during the same perio

A SURVEY OF MARCHANTIALES FROM MADAGASCAR

Based on the authors’ recent collections and on older herbarium specimens (PC, TAN, EGR), the species of Marchantiidae (Marchantiopsida, Marchantiophyta) of Madagascar are reported with their description based on Malagasy specimens. A distribution map for each taxon is provided. Among the fifteen taxa identified, six are newly recorded for the island, including a new synonymy: Asterella coronata (Steph.) H.A.Mill = Asterella bachmannii (Steph.) S.W. Arnell. Most of Marchantiidae live in xeric areas (Riccia species, Exormotheca pustulosa Mitt.) or in exposed, only temporarily wet stations (Plagiochasma, Asterella). This preliminary study shows the evidence of under-prospection of such areas in Madagascar for bryophytes and the need of taxonomic work to clarify some genera (Riccia, Asterella, Plagiochasma) and to confirm the species hitherto reported

Win-win opportunities combining high yields with high multi-taxa biodiversity in tropical agroforestry

Resolving ecological-economic trade-offs between biodiversity and yields is a key challenge when addressing the biodiversity crisis in tropical agricultural landscapes. Here, we focused on the relation between seven different taxa (trees, herbaceous plants, birds, amphibians, reptiles, butterflies, and ants) and yields in vanilla agroforests in Madagascar. Agroforests established in forests supported overall 23% fewer species and 47% fewer endemic species than old-growth forests, and 14% fewer endemic species than forest fragments. In contrast, agroforests established on fallows had overall 12% more species and 38% more endemic species than fallows. While yields increased with vanilla vine density and length, non-yield related variables largely determined biodiversity. Nonetheless, trade-offs existed between yields and butterflies as well as reptiles. Vanilla yields were generally unrelated to richness of trees, herbaceous plants, birds, amphibians, reptiles, and ants, opening up possibilities for conservation outside of protected areas and restoring degraded land to benefit farmers and biodiversity alike

Concepte de Modèle Ecologique pour la Zone Humide Alaotra

The wet zone Alaotra consists of the largest lake of Madagascar with about 20,000 ha of open-water and up to 23,000 ha of marshes. This wet zone is unique by the presence of an endemic fauna, and its marshes consist of a monospecific vegetation. The local communities directly depend on this wet zone with fishing and agriculture being an integral part of the region’s economy. Consequently, various anthropological pressures such as burning of the vegetation, over-fishing, pollution of the lake by the use of weed-killers, and sedimentation of the watersheds due to heavy erosions of the surrounding hills, negatively impact on this ecosystem. The wet zone Alaotra has been classified as an official Ramsar wetland site since 2003 and also as a SAPM protected area in January 2007 because of its ecological importance and its various threats to this ecosystem. The objective of this article is to present and describe the ecological model, which consists of the identification of the various ecological entities as well as their interdependence, in order to justify the wetlands classification as both a Ramsar and a New Protected Area site. The model has been adopted from Ogden (2005), and its ecological entities integrated in the conceptual model are derived from various research works conducted on the wet zone Alaotra. The model will be critically important in convincing the local authorities as well as the local communities to work together with the researchers, in order to implement the best conservation practices and ensure the sustainable management of the wet zone Alaotra. RESUMELa zone humide d’Alaotra comprend le plus grand lac de Madagascar qui a une superficie de 20,000 ha ainsi qu’un marais d’une superficie de 23,000 ha. Elle est unique au monde par l’existence d’une faune endémique dont l’habitat est un marais composé d’une végétation mono-spécifique. La vie de la population dépend de cette zone humide, si on ne prend en compte que la pêche, l’agriculture, et l’économie de la région. Cependant, différentes pressions anthropiques affectent cet écosystème telles que la mise à feu du marais et la surpêche, la pollution du lac par l’utilisation des herbicides et la sédimentation à cause d’une forte érosion des bassins versants. Ces pressions causent des impacts sur la faune et la flore de la zone humide d’Alaotra. Cela entraîne un changement environnemental de l’Alaotra, comme la fragmentation du marais, constatée depuis plus de dix ans, et un danger pour la vie de la population aussi bien dans le présent que dans le futur. L’importance de cette zone humide ainsi que les différentes menaces dont elle est la cible, ont conduit a sa classification en tant que site Ramsar en 2003 et fait partie du Système Aire Protégée en janvier 2007. Cet article a pour objectif de décrire le concept de modèle écologique, qui consiste à identifier les différentes entités écologiques ainsi que leur interdépendance, afin de justifier son classement dans le site Ramsar et en Nouvelle Aire Protégée. Ces entités résultent des différents travaux de recherche effectués sur la zone humide Alaotra. Le modèle adopté est celui d’Ogden (2005). Le modèle écologique présent est une de clé principales de la restauration qui devrait permettre de convaincre les autorités locales ainsi que les villageois à assurer ensemble avec les chercheurs la meilleure conservation et la gestion durable de la zone humide Alaotra.