Dynamique de la mangrove de la région du Sud-ouest de Madagascar face aux actions anthropiques et au changement climatique. L’exemple des formations à palétuviers

Cette étude a pour objectifs l’identification et la cartographie des aires de répartition des mangroves de la région de Toliara dans le sud-ouest de Madagascar, le diagnostic de l’état actuel de la mangrove ainsi que sa dynamique d’évolution durant les sept dernières décennies, afin de déterminer les différents facteurs d’évolution. Pour atteindre ces objectifs, et ainsi combler l’insuffisance des connaissances de ces milieux dans cette région, deux approches ont été adoptées : la télédétection satellitaire d’une part et les recherches sur terrain  d’autre part. La télédétection se base sur l’analyse diachronique d’images Spot de 1987, 2012 et 2014, et de photographies aériennes (1949). Les résultats montrent une évolution contrastée entre progression, stabilité et régression. Les régressions sont liées à des dynamiques géomorphologiques et hydrologiques  et aussi à l’action de l’homme par coupes, feux, divagation de bétail, etc

Les changements d’occupation et d’usage du sol, des processus multidimensionnels complexes qui affectent la biodiversité

Différents exemples localisés en Afrique de l’Ouest montrent l’intérêt de combiner des approches des dimensions humaine et physique et des entrées par le paysage, c’est-à-dire en combinant les dimensions matérielle et sensible, pour approfondir l’analyse de l’occupation des sols et de leurs dynamiques d’évolution. Ils montrent aussi l’intérêt de l’analyse des changements à différentes échelles d’étude, et la nécessité de définir la résolution des données en adéquation avec l’objectif social ou écologique de l’analyse spatiale. Les conclusions qui diffèrent profondément de celles qui, par exemple, sont purement orientées par l’écologie de la conservation et habituellement énoncées sur les transformations des milieux et des paysages. Ces approches permettent de réaliser la distinction impérative entre usage et occupation des sols « remettant en cause les états de référence à travers une lecture dynamique des processus environnementaux », aidées en cela par l’utilisation combinée de données discrètes et continues, et ouvrant ainsi de nouvelles voies à la modélisation LULCC

Vegetation maps based on remote sensing are informative predictors of habitat selection of grassland birds across a wetness gradient

Vegetation is a major environmental factor influencing habitat selection in bird species. High resolution mapping of vegetation cover is essential to model the distribution of populations and improve the management of breeding habitats. However, the task is challenging for grassland birds because microhabitat variations relevant at the territory scale cannot be measured continuously over large areas to delineate areas of higher suitability. Remote sensing may help to circumvent this problem. We addressed this issue by using two methods. We (i) mapped the continuous Ellenberg index of moisture and (ii) identified 5 vegetation classes distributed accross the wetness gradient. These two methods produced consistent output maps, but they also provided more information about vegetation structure, and possibly trophic resources. In spite of the apprent uniformity of meadows, our data show that birds do not settle randomly along the moisture and vegetation gradients. Overall birds tend to avoid the driest vegetation classes, i.e. the highest grounds. Thus, vegetation maps based on remote sensing could be valuable tools to study habitat selection and niche partition in grassland bird communities. It is also a valuable tool for conservation and habitat management

Changes in corticospinal excitability and the direction of evoked movements during motor preparation: A TMS study

BACKGROUND: Preparation of the direction of a forthcoming movement has a particularly strong influence on both reaction times and neuronal activity in the primate motor cortex. Here, we aimed to find direct neurophysiologic evidence for the preparation of movement direction in humans. We used single-pulse transcranial magnetic stimulation (TMS) to evoke isolated thumb-movements, of which the direction can be modulated experimentally, for example by training or by motor tasks. Sixteen healthy subjects performed brisk concentric voluntary thumb movements during a reaction time task in which the required movement direction was precued. We assessed whether preparation for the thumb movement lead to changes in the direction of TMS-evoked movements and to changes in amplitudes of motor-evoked potentials (MEPs) from the hand muscles. RESULTS: When the required movement direction was precued early in the preparatory interval, reaction times were 50 ms faster than when precued at the end of the preparatory interval. Over time, the direction of the TMS-evoked thumb movements became increasingly variable, but it did not turn towards the precued direction. MEPs from the thumb muscle (agonist) were differentially modulated by the direction of the precue, but only in the late phase of the preparatory interval and thereafter. MEPs from the index finger muscle did not depend on the precued direction and progressively decreased during the preparatory interval. CONCLUSION: Our data show that the human corticospinal movement representation undergoes progressive changes during motor preparation. These changes are accompanied by inhibitory changes in corticospinal excitability, which are muscle specific and depend on the prepared movement direction. This inhibition might indicate a corticospinal braking mechanism that counteracts any preparatory motor activation

The Confidence Database

Understanding how people rate their confidence is critical for the characterization of a wide range of perceptual, memory, motor and cognitive processes. To enable the continued exploration of these processes, we created a large database of confidence studies spanning a broad set of paradigms, participant populations and fields of study. The data from each study are structured in a common, easy-to-use format that can be easily imported and analysed using multiple software packages. Each dataset is accompanied by an explanation regarding the nature of the collected data. At the time of publication, the Confidence Database (which is available at https://osf.io/s46pr/) contained 145 datasets with data from more than 8,700 participants and almost 4 million trials. The database will remain open for new submissions indefinitely and is expected to continue to grow. Here we show the usefulness of this large collection of datasets in four different analyses that provide precise estimations of several foundational confidence-related effects