Search results for "Global changes"
showing 10 items of 533 documents
Date de semis du mil et variabilité intrasaisonnière des précipitations au Niger
2012
Le rôle du déterminisme pluviométrique, et plus spécifiquement du démarrage de la saison des pluies, sur les pratiques agricoles a été évalué à partir de l'exemple de la culture du mil dans la région de Niamey parce que celle-ci y occupe une place prépondérante. Cette analyse, à l'interface du climat et des sociétés, a été réalisée à partir d'enquêtes agronomiques conduites en milieu paysan sur l'observatoire AMMA-CATCH Niger sur un carré de100 km x 100 km au NE de Niamey entre 2004 et 2007. Par ailleurs, le démarrage de la saison des pluies repose sur des considérations subjectives qui dépendent fortement de l'utilisateur. Ainsi, ce dernier est de nature équivoque dans ces régions semi-ari…
SURCOTES MARINES DANS LE GOLFE DU LION ET FORCAGES ATMOSPHERIQUES : VARIABILITE CONTEMPORAINE ET FUTURE (1950-2100)
2010
Sea surges in the Gulf of Lions are mainly forced by southerly and south-easterly winds. This regional-scale atmospheric circulation is leading by a strong zonal gradient between low pressure system over the Bay of Biscay and high pressure over central Europe. This synoptic-scale circulation mostly happens during “Greenland Above” weather regime. In the second half of the 20th century, a slow increase of the sea-level pressure over central Europe increased the probability of having “Greenland Above” weather types associated with a southerly atmospheric circulation in the Gulf of Lions, thus leading to strong surges. A linear regression is used to simulate the interannual variability of high…
Le paysage nocturne de montagne, nouvelle identité visuelle et outil d’action collective pour des territoires en transitions ?
2017
Global-Scale Environmental Niche and Habitat of Blue Shark (Prionace glauca) by Size and Sex: A Pivotal Step to Improving Stock Management
2022
25 pages, 10 figures, 2 tables, supplementary material https://www.frontiersin.org/articles/10.3389/fmars.2022.828412/full#supplementary-material.-- Data Availability Statement: The blue shark habitat data are available on the JRC Data Catalogue (https://data.jrc.ec.europa.eu/dataset?q=fish%20habitat) (or upon request) and habitat maps are available online (https://fishreg.jrc.ec.europa.eu/web/fish-habitat/habitatmapping). Chlorophyll-a data are available online (https://oceancolor.gsfc.nasa.gov/cgi/l3). The abiotic environmental and mesopelagic micronekton data are available online (https://marine.copernicus.eu/access-data).
Zones d'ammonites et de foraminifères du Vraconnien au Turonien : Une comparasion entre les domaines boréal et téthysien (NW Europe / Tunisie central…
2008
International audience; Depuis la fin du 19ème siècle, l'intervalle comprenant l'Albien supérieur élevé, le Cénomanien, le Turonien et le Coniacien basal a été subdivisé d'abord en zones d'ammonites puis, à partir du milieu du 20ème siècle, en zones de foraminifères planctoniques, deux groupes de macro- et de microfossiles particulièrement efficaces en bio-chronostratigraphie grâce à leur taux d'évolution rapide. Toutefois, des différences de compositions fauniques entre le domaine boréal (Europe du Nord-Ouest) et le domaine téthysien (Méditerranée) ont longtemps empêché des corrélations précises entre ces deux domaines. Aujourd'hui, dans un intervalle de temps couvrant environ 16 millions …
Approche d'un territoire de montagne : occupations humaines et contexte pédo-sédimentaire des versants du col du Petit-Saint-Bernard, de la Préhistoi…
2014
As part of a multi-year programme, survey campaigns have been carried out on both slopes of the Petit-Saint-Bernard pass (2188 m, western Alps), at an altitude of between 750 and 3000 m. The method employed abandons ground-based surveying in favour of multiple manual surveys carried out on selected topographic contexts down to the base of the Holocene fill. The results obtained document the longterm development of the pedo-sedimentary dynamic and the occupation of the different altitude stages. The significance of the archaeological data collected is discussed in relation to the state of knowledge in a comparison area including the neighbouring valleys of the western Alps, to existing settl…
Stepping up to genome scan allows stock differentiation in the worldwide distributed blue shark Prionace glauca
2023
The blue shark Prionace glauca is a top predator with one of the widest geographic distributions of any shark species, yet classified as critically endangered in the Mediterranean Sea, and Near Threatened globally. Previous genetic studies did not reject the null hypothesis of a single global population across the worldwide species range. Blue shark situation was proposed as a possible archetype of the ‘grey zone of population differentiation’, coined to designate cases where population structure may be too recent or too faint to be detected using a limited set of markers. Here, blue shark samples collected throughout its global range were sequenced using a specific ddRAD method (DArTseq; G…
Phytoplankton in the physical environment: beyond nutrients, at the end, there is some light
2009
This article summarizes the outcomes of the 15th Workshop of the International Association for Phytoplankton Taxonomy and Ecology. Four major issues dealing with the role of physical factors in phytoplankton ecology were addressed in the articles of this special volume: global change and its likely impacts on phytoplankton, the role of physical factors in the autecology of particular species, impacts on the inocula for the following years, and the role of light in shaping phytoplankton dynamics. Case studies from different types of aquatic environments (rivers, deep and shallow lakes, floodplain lakes, wetlands, oxbows, and even the deep ocean) and from diverse geographical locations (not o…
Fluid-pressure controlled soft-bed deformation sequence beneath the surging Breiðamerkurjökull (Iceland, Little Ice Age).
2009
16 pages; International audience; The general subject of this paper is subglacial deformation beneath Breiðamerkurjökull, a surging Icelandic glacier. More specifically it discusses the evolution and the role of fluid pressure on the behaviour of subglacial sediments during deformation. During Little Ice Age maximum, the two outcrops studied, North Jökulsarlon (N-Jk) and Brennhola-Alda (BA), were located at 2550 m and 550 m respectively from the front of the Breiðamerkurjökull. Sedimentological analysis at the forefield of the glacier shows thick, coarse glaciofluvial deposits interbedded with thin, fine-grained shallow lacustrine/swamp deposits, overlain by a deformed till unit at N-Jk. BA…
Evaporite karst in Italy: A review
2017
none 16 si Although outcropping rarely in Italy, evaporite (gypsum and anhydrite) karst has been described in detail since the early 20th century. Gypsum caves are now known from almost all Italian regions, but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum mines in Piedmont. During the late 80s and 90s several multidisciplinary studies were carried out in many gypsum areas, resulting in a comprehensive overview, promoting further research in these special karst regions. More recent and detailed studies focused…