How does climate change Impact island rainforests: first measurements in The Lesser Antilles archipelago

International audienceRainforests in tropical islands are characterized by high endemism and unusual structures. Canopies are lower than in continental areas with a similar climate, but the number of trees per hectare is much higher. It is likely that these structural attributes are due to the frequency of hurricanes but also more generally to some peculiarities of island climates.Recent works show that in areas where plants are subject to seasonal drought, the metabolism of tropical trees negatively responds to rising temperatures and rainfall reduction. Given the particularities of island ecosystems, we wanted to study the behavior of forests growing in climates without true dry season.The results obtained on four 1-hectare plots (4312 trees) show that during the last nine years, tree growth has accelerated and at the same time, tree mortality has increased - although the estimation of mortality is more uncertain. These joint trends reflect a significant acceleration in the turnover of tree stands.The measurements carried out thanks to the "Forest Ecosystems Observatory" put in place since 2010, demonstrate that the Caribbean island rainforests are impacted by the current climate change and that they respond in a singular way. The results obtained do not provide information on changes in biodiversity or loss of endemic species, but they suggest that Lesser-Antilles rainforests are reducing their carbon storage capacity

Frugivory and Seed Dispersal by Terrestrial Mammals

International audienc

Typologie des ripisylves des rivières de Guadeloupe, un premier pas vers le développement de techniques de génie végétal avec des espèces locales

National audienceThe PROTÉGER project aims to promote soil bioengineering techniques to preserve the extreme biodiversity of Guadeloupe's riparian environments, while protecting the population and their property from the risks incurred during river floods and cyclonic events. The first phase of the project consisted in describing the archipelago's riparian zones, in order to know their natural patterns and to be able to draw inspiration from them to develop nature-based solutions. Out of the 270 banks sampled, 302 species, 231 of which were native, were encountered, representing 10% of the local flora, reflecting the highly forested nature of the archipelago and its exceptional diversity. The analysis of these surveys allowed us to define 12 types of riparian vegetation, and to document 80 species that could potentially be used in soil bioengineering. The study presents 30 of them in the form of individual sheets available on the project website with their description, phenology, protection status, ecology, use and conditions of implementation. Beyond the typology and the specific sheets, this work also showed the alarming state of the Guadeloupe’s riparian forests, in particular on the downstream part of the rivers, with habitats degraded by pollution and the presence of invasive alien species.Le projet PROTÉGER vise à promouvoir les techniques de génie végétal pour préserver l’extrême biodiversité des milieux rivulaires de Guadeloupe, tout en protégeant la population et leurs biens, des risques encourus lors des crues de rivière et des évènements cycloniques. La première phase du projet a consisté à décrire les ripisylves de l’archipel, afin d’en connaitre les modèles naturels et de pouvoir s’en inspirer pour développer des solutions fondées sur la nature. Sur les 270 berges échantillonnées, 302 espèces dont 231 indigènes ont été rencontrées, soit 10 % de la flore locale, reflétant la nature très forestière de l’archipel et son exceptionnelle diversité. L’analyse de ces relevés a permis de définir 12 types de ripisylves, et de documenter 80 espèces potentiellement utilisables en génie végétal. L’étude présente 30 d'entre elles sous forme de fiches individuelles disponibles sur le site internet du projet avec leur description, leur phénologie, leur statut de protection, leur écologie, leur usage et leur condition d’utilisation. Au-delà de la typologie et des fiches spécifiques, ce travail a aussi montré l’état alarmant des ripisylves de Guadeloupe, notamment sur la partie aval des cours d‘eau, avec des habitats dégradés par la pollution et la présence d’espèces exotiques envahissantes

L’information économique, XVIe-XIXe siècle

Coûteuse, inégalement partagée, l’information est une arme décisive face à l’incertitude. Les travaux économiques récents, s’éloignant de l’orthodoxie néo-classique, ont mis en valeur le rôle central de l’information dans le fonctionnement des marchés. De fait, du XVIe au XIXe siècle, quand s’intensifient les circulations et les relations commerciales, les différents acteurs marquent leur appétit d’information, et agissent ensuite en fonction de ce qu’ils croient savoir. Ainsi, l’information recueillie sur l’économie joue elle-même un rôle dans l’économie. Elle est donc un élément intrinsèque du fonctionnement même des marchés, une donnée des jeux de l’échange. Les études réunies ici, à la suite de deux journées d’études réalisées en 2004 et 2006 et rassemblant les meilleurs spécialistes, nous emmènent des correspondances marchandes et circulaires commerciales aux Affiches, Annonces et autres feuilles d’information. Mais elles soulignent aussi l’action d’un autre acteur : depuis les initiatives de Colbert jusqu’à l’essor de la Statistique générale de la France, l’État s’est affirmé comme un grand collecteur mais aussi producteur d’information économique. De sorte que, aussi libérale que fût devenue sa politique, au XIXe siècle, il a continué de jouer un rôle crucial, quand lui seul pouvait rassembler des données dispersées. En avoir ou pas : depuis l’époque moderne, chacun était conscient de l’enjeu que représentait l’information économique. Là encore, le passé éclaire notre présent

CARIB-COAST caribbean network for coastal risks related with climate change

International audienc

Villes et districts industriels en Europe occidentale (XVIIe-XXe siècle)

Au moment où les pays occidentaux redécouvrent les avantages de la production flexible et des communautés territoriales d'entreprises, ce livre s'interroge sur le rôle de la ville dans le fonctionnement des systèmes productifs locaux. Il étudie la place de la ville et des municipalités dans l'organisation du district industriel et l'effet, en retour, de la présence du district sur le développement de la ville. Il met en lumière le rôle des valeurs et des institutions urbaines comme éléments constitutifs du district (coopération entre firmes, consensus social et mobilité). Il analyse enfin les mécanismes d'adaptation qui ont souvent permis aux districts de survivre aux mutations industrielles que l'Europe a connues depuis l'époque moderne

Pre-assessments of plant conservation status in islands: the case of French Overseas Territories

International audienceAssessment methods have been developed to estimate a preliminary conservation status for species and subsequently to facilitate the building of Red Lists. Such pre-assessment methods could be particularly useful in the French Overseas Territories (FOTs) where Red Lists tend to be outdated or absent and where a high number of endemic species face detrimental anthropogenic pressures. We first aimed to conduct a preliminary assessment (hereafter, pre-assessment) of the conservation status of endemic plants from Guadeloupe, Martinique, Réunion, Mayotte, French sub-Antarctic islands, New Caledonia, and Scattered Islands. We then compared the various methods used in conducting the pre-assessment and discussed ways to adapt these methods to small territories. We compiled occurrence data of endemic species identified thanks to a previous taxonomic work and pre-assessed their conservation status under Red List criteria A and B and the use of a Random Forest algorithm. We then measured the accuracy, specificity, and sensitivity of each method based on existing Red Lists. The Random Forest algorithm and a method based on range-size performed best at correctly attributing conservation status. Using these pre-assessment methods, we estimated that up to 60% of the endemic flora of the FOTs is potentially threatened. Range restriction but also anthropogenic pressures were key factors that explained these risks. Pre-assessment methods are useful tools to get a first measure of species conservation status. These methods should be adapted to the territories considered and their conservation issues in order to reach a good performance

Pre-assessments of plant conservation status in islands: the case of French Overseas Territories

International audienceAssessment methods have been developed to estimate a preliminary conservation status for species and subsequently to facilitate the building of Red Lists. Such pre-assessment methods could be particularly useful in the French Overseas Territories (FOTs) where Red Lists tend to be outdated or absent and where a high number of endemic species face detrimental anthropogenic pressures. We first aimed to conduct a preliminary assessment (hereafter, pre-assessment) of the conservation status of endemic plants from Guadeloupe, Martinique, Réunion, Mayotte, French sub-Antarctic islands, New Caledonia, and Scattered Islands. We then compared the various methods used in conducting the pre-assessment and discussed ways to adapt these methods to small territories. We compiled occurrence data of endemic species identified thanks to a previous taxonomic work and pre-assessed their conservation status under Red List criteria A and B and the use of a Random Forest algorithm. We then measured the accuracy, specificity, and sensitivity of each method based on existing Red Lists. The Random Forest algorithm and a method based on range-size performed best at correctly attributing conservation status. Using these pre-assessment methods, we estimated that up to 60% of the endemic flora of the FOTs is potentially threatened. Range restriction but also anthropogenic pressures were key factors that explained these risks. Pre-assessment methods are useful tools to get a first measure of species conservation status. These methods should be adapted to the territories considered and their conservation issues in order to reach a good performance