Circuit court du marché des produits agricoles: pour une gestion efficace du paysage ouvert, cas du bassin-versant de Maningory, Madagascar

Separated by the Zahamena National park, smallholder farmers in the western part of the Maningory watershed largely rely on irrigated rice cropping, whereas those on the eastern front mainly rely on cash crops cultivated using slash and burn practices known as tavy in addition to rice cultivation. The watershed is made up of a mosaic of open landscapes, defined in this article as all grasslands, degraded cropland, and agricultural land. This mosaic is interspersed with the forests of the Zahamena National Park as well as those of eucalyptus reforestation, and Lake Alaotra’s marshlands. As cultivable rice parcels become increasingly scarce, farmers are pushed to extend their farming into the tanety and open landscape. This study aims to gain a better understanding of the role of local agricultural product markets commercialization in landscape changes. Two approaches were implemented to this end, namely companion modelling using role-playing games and personal interviews. Results show that small farming economy is largely based on local subsistence. Most of the agricultural production is used for personal consumption, leading to a weak resilience of the landscape and suggesting high vulnerability towards the market. The role of the market on land use strategies remains allusive and intrinsically linked to the product prices, as well as to the ease of access to locations. RésuméSéparés par le rideau forestier du Parc National Zahamena, les paysans du côté Ouest du bassin versant du Maningory vivent en grande partie de la riziculture irriguée, alors que sur le versant Est, la culture itinérante sur brûlis ou tavy caractérise les pratiques agricoles des paysans. Ils sont connus pour les cultures pluviales de riz, d’arachide, de haricot et les cultures de rente de girofle, de café, et de letchi. Le bassin versant est constitué de la forêt naturelle de l’Aire Protégée, de la forêt de reboisement d’eucalyptus et des zones marécageuses autour du Lac Alaotra. Cet ensemble forme une mosaïque de paysage ouvert—défini dans cet article comme l’ensemble des zones herbeuses et arbustives, des zones de culture sur formations dégradées, ainsi que des espaces cultivables en bas-fond et en bas de pente. Le constat est que les surfaces des rizières cultivables deviennent de plus en plus restreintes, incitant les paysans à coloniser les tanety ou le paysage ouvert pour les pratiques agricoles. Cet article tente de comprendre le rôle du circuit court de commercialisation des produits agricoles dans le changement d’occupation de ce paysage. Deux approches ont été utilisées à cette fin : la modélisation d’accompagnement à travers un jeu de rôle, et des entretiens individuels. Les résultats démontrent que l’économie paysanne est surtout basée sur une économie de subsistance. La plupart de la production agricole est destinée à l’autosubsistance, incitant ainsi une faible résilience du paysage et suggère une forte vulnérabilité face à l’économie de marché. Le rôle du marché dans les stratégies d’occupation du sol reste encore allusif mais intrinsèquement lié au prix des produits agricoles et à l’accessibilité des sites

Ecological variability and carbon stock estimates of mangrove ecosystems

Abstract: Mangroves are found throughout the tropics, providing critical ecosystem goods and services to coastal communities and supporting rich biodiversity. Despite their value, world-wide, mangroves are being rapidly degraded and deforested. Madagascar contains approximately 2% of the world's mangroves, >20% of which has been deforested since 1990 from increased extraction for charcoal and timber and conversion to small to large-scale agriculture and aquaculture. Loss is particularly prominent in the northwestern Ambaro and Ambanja bays. Here, we focus on Ambaro and Ambanja bays, presenting dynamics calculated using United States Geological Survey (USGS) national-level mangrove maps and the first localized satellite imagery derived map of dominant land-cover types. The analysis of USGS data indicated a loss of 7659 ha (23.7%) and a gain of 995 ha (3.1%) from 1990-2010. Contemporary mapping results were 93.4% accurate overall (Kappa 0.9), with producer's and user's accuracies ≥85%. Classification results allowed partitioning mangroves in to ecologically meaningful, spectrally distinct strata, wherein field measurements facilitated estimating the first total carbon stocks for mangroves in Madagascar. Estimates suggest that higher stature closed-canopy mangroves have average total vegetation carbon values of 146.8 Mg/ha (±10.2) and soil organic OPEN ACCESS Forests 2014, 5 178 carbon of 446.2 (±36.9), supporting a growing body of studies that mangroves are amongst the most carbon-dense tropical forests

Mapping to explore the challenges and opportunities for reconciling artisanal gem mining and biodiversity conservation

Artisanal and small-scale mining (ASM) provides a vitally important livelihood for millions of people in many low- and middle-income countries. ASM can result in habitat clearance, increased hunting pressure, pollution, and sedimentation of waterways. Consequently, where mineral and biological wealth coincide, there are trade-offs. Here, we combine geological data with four datasets capturing conservation priorities, to evaluate where, and to what extent, mining may impact biodiversity, and to explore opportunities for both to co-exist. We use Madagascar as a case study: a biodiversity hotspot rich in economically important minerals where artisanal gem mining has conflicted with biodiversity conservation. We identify areas of Madagascar most likely to host primary deposits of gems and find that 11%–14% of the most important area for biodiversity on the island could host primary gem deposits. However, we also identify 7 million hectares (80%) of potentially prospective land which is outside of these areas. Establishing decentralised, community-managed zones for licensed ASM in such areas could help to incentivise formalisation and minimise social and environmental trade-offs. Our mapping approach could be applied in other countries to encourage the establishment of designated zones for ASM in places where mining does not conflict with conservation

Rapport final: Aménagement participatif d'un bassin versant de la Mandraka, Madagascar

Les protéines intrinsèquement désordonnées (IDP), pendant longtemps ignorées, s’avèrent d’un grand intérêt biologique. En effet, malgré leur manque de structure secondaire, ces protéines ont une activité et sont impliquées dans de nombreuses interactions protéine-protéine ou protéine-ligand, notamment en ce qui concerne les maladies neurodégénératives. L'étude des IDP devient un enjeu majeur afin de comprendre cette partie de la biologie, méconnue jusqu'à il y a peu. Malheureusement, une grande majorité des outils développés en biologie pour les protéines repliées ne sont pas applicables aux IDP puisqu'elles supposent la présence d'une structure tertiaire. Bien que de plus en plus de groupes de recherches s'intéressent à ces protéines et aux façons de les étudier, il est nécessaire de créer ou de découvrir de nouveaux moyens d'analyser les IDP. Trois grandes méthodes d'analyse des IDP ont été développées durant cette thèse. Dans un premier temps, nous parlerons de la détermination de la dimension fractale des protéines afin de connaître leur comportement hydrodynamique. Nous avons pour cela utilisé une méthode propre à la chimie des polymères que nous avons appliqué à des peptides polyproline ainsi qu'à une IDP salivaire riche en proline. Dans un deuxième temps, nous décrirons comment prédire ces conformations à partir des déplacements chimiques. Cette réflexion a menée à l’écriture de deux logiciels gratuits RamaDA/RamaDP. Enfin, le dernier point donnera un aperçu de l'étude complète de l’interaction entre une protéine structurée et son partenaire désordonné à partir de multiples données expérimentales, des outils précédents et d'un générateur aléatoire de conformations.Intrinsically disordered proteins (IDP), ignored for a long time, turn out to be of biological interest. Indeed, although they lak of secondary structure, these proteins have an activity and are implicated in numerous protein-protein or protein-ligand interactions, in particular concerning neurodegenerative diseases. The study of IDP becomes a major issue in order to understand this part of biology, unknown until lately. Unfortunately, a vast majority of already developped tools in biology for folded proteins can not be applied to IDP because this tools are based on the presence of secondary structure. Though more and more research groups are interested in these proteins and in the ways of studying them, it is necessary to create or discover new means of analysing IDP. Three important analyse methods of IDP have been developped during this PhD. First, we will talk about the determination of the proteins’ fractal dimension in order to know their hydrodynamic behaviour. We have used a method dedicated to polymers that we have applied on polyproline peptides and on a proline-rich salivary IDP. Then, we will describe how to predict conformations from the protein chemical shifts. This discussion led to the development of two freely available softwares RamaDA/RamaDP. Finally, the last chapter will give an overview of the complete study of the interaction between a folded protein and its disordered partner, thanks to various expérimental data, the previous tools and a random conformation generator

Bioclimatic envelope models predict a decrease in tropical forest carbon stocks with climate change in Madagascar

Recent studies have underlined the importance of climatic variables in determining tree height and biomass in tropical forests. Nonetheless, the effects of climate on tropical forest carbon stocks remain uncertain. In particular, the application of process-based dynamic global vegetation models has led to contrasting conclusions regarding the potential impact of climate change on tropical forest carbon storage. Using a correlative approach based on a bioclimatic envelope model and data from 1771 forest plots inventoried during the period 1996–2013 in Madagascar over a large climatic gradient, we show that temperature seasonality, annual precipitation and mean annual temperature are key variables in determining forest above-ground carbon density. Taking into account the explicative climate variables, we obtained an accurate (R2 = 70% and RMSE = 40 Mg ha−1) forest carbon map for Madagascar at 250 m resolution for the year 2010. This national map was more accurate than previously published global carbon maps (R2 ≤ 26% and RMSE ≥ 63 Mg ha−1). Combining our model with the climatic projections for Madagascar from 7 IPCC CMIP5 global climate models following the RCP 8.5, we forecast an average forest carbon stock loss of 17% (range: 7–24%) by the year 2080. For comparison, a spatially homogeneous deforestation of 0.5% per year on the same period would lead to a loss of 30% of the forest carbon stock. Synthesis. Our study shows that climate change is likely to induce a decrease in tropical forest carbon stocks. This loss could be due to a decrease in the average tree size and to shifts in tree species distribution, with the selection of small-statured species. In Madagascar, climate-induced carbon emissions might be, at least, of the same order of magnitude as emissions associated with anthropogenic deforestation

The Mangroves of Ambanja and Ambaro Bays, Northwest Madagascar: Historical Dynamics, Current Status and Deforestation Mitigation Strategy

Madagascar contains Africa’s fourth largest extent of mangroves, representing approximately 2% of the global distribution. Since 1990, more than 20% of Madagascar’s mangrove ecosystems have been heavily degraded or deforested due primarily to increased harvest for charcoal and timber and the expansion of agriculture and aquaculture. Anthropogenic-driven loss is particularly prominent in the north-western Ambanja and Ambaro Bays (AAB). At over 24,000 ha, AAB is one of Madagascar’s largest mangrove ecosystems, including prominent estuaries fed by rivers and streams originating in the country’s highest mountain range. Similar to the national rate, AAB has experienced approximately 20% loss since 1990, driven primarily by over-harvesting for charcoal and timber. Continued loss threatens the livelihoods and wellbeing of thousands of residents who rely on the many goods and services provided by a healthy, relatively intact mangrove ecosystem. To combat this loss, Blue Ventures (BV), in partnership with local communities and the University of Antananarivo, is working to protect, restore and encourage the sustainable use of mangroves. BVs’ Blue Forests project aims to help maintain and diversify local livelihoods and to sustainably manage mangroves and their associated biodiversity in AAB, as well as throughout western Madagascar. This chapter provides an overview of the biophysical characteristics, historic dynamics and current status of the AAB mangrove ecosystem, and mitigation strategies being implemented through BVs’ Blue Forests project