Search results for " change"
showing 10 items of 3731 documents
Dynamique sédimentaire des dépôts post-rift du bassin intérieur du Gabon.
2006
14 pages; International audience
Synthèse préliminaire des travaux menés sur le bassin de Benguela (Sud Angola) : implications sédimentologiques, paléontologiques et structurales.
2006
12 pages; International audience; Les travaux menés dans le bassin de Benguela ont apporté une moisson de nouvelles données de terrain quant à la période apto-albienne de ce secteur ouest africain. Outre les résultats majeurs obtenus en ce qui concerne les faunes d'ammonites jusqu'alors peu étudiées dans ce bassin, et qui ont permis des corrélations indispensables pour la compréhension du fonctionnement de la sédimentation, cette étude a permis de mettre en évidence une compartimentation remarquable de la sédimentation et des structures de tectonique salifère. Des tels résultats ont une portée à la fois fondamentale et appliquée. En effet, il paraît que le bassin de Benguela soit un des rar…
The role of slabs and oceanic plate geometry in the net rotation of the lithosphere, trench motions, and slab return flow
2012
International audience; [1] Absolute plate motion models with respect to a deep mantle reference frame (e.g., hot spots) typically contain some net rotation (NR) of the lithosphere. Global mantle flow models for the present-day plate setting reproduce similarly oriented NRs but with amplitudes significantly smaller than those found in some high NR Pacific hot spot reference frames. It is therefore important to understand the mechanisms of NR excitation, which we attempt here with two-dimensional cylindrical models of an idealized Pacific domain. We study the influence of slab properties, oceanic ridge position, continental keels, and a weak asthenospheric layer on NR and trench migration. F…
Impacts of Integrated Weed management in cropping systems on N2O emissions from soils
2014
International audience
Drought affects weed emergence in cover crops of no-till systems
2014
Session 7 - Crop science in changing environmentsEAEcolDur; International audience
Très longs épisodes secs hivernaux dans le bassin méditerranéen : variabilité spatio-temporelle et impact sur la production céréalière en Espagne.
2018
This study concerns the long winter sequences without rain at the whole Mediterraneanbasin scale. Objectives are (i) to define theses extreme events as geographical and climatological objectscharacterized by a location, a spatial extension and a temporal length and (ii) measured impacts of these eventson the cereal production in Spain. 76 events of very long dry spells (eVLDS) are detected over the 1957-2013period. These eVLDS are grouped into 4 typical recurrent configurations at the Mediterranean basin scale: North-East, West, Scattered & Localised and South-East. The eVLDS have a greater impact on barley, wheat and oatyields (winter crops grown through rainfed agriculture) than rainfall …
Phenological model performance to warmer conditions: application to Pinot noir in Burgundy.
2014
<p style="text-align: justify;"><strong>Aim</strong>: The current work aims to assess the performance of two phenological models - a linear model (<em>Grapevine Flowering</em> <em>Véraison</em> model, <em>GFV</em>) and a curvilinear model (<em>Wang and</em> <em>Engel</em> model, <em>WE</em>) - to warmer temperature conditions for the grapevine variety Pinot noir in Burgundy.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Simulations using historical data from the 1973-2005 period were similar between models and consistent with observations. To mimic pot…
Etude des interactions plantes-microbes et microbes-microbes au sein de la rhizosphère, sous un aspect coûts-bénéfices, dans un contexte de variation…
2013
Understanding the interactions that bind plants and soil microorganisms is an essential step for the sustainable management of ecosystems, especially in agriculture. The ecosystem services resulting from such interactions include plant productivity which responds, in part, to the food requirements of the world's population and the regulation of biogeochemical cycles. These ecosystem services depend on trophic links between the two partners in the interaction and can be represented by a tradeoff between the costs and benefits for each partner. Plants, being autotrophic organisms or primary producers, are key organisms which introduce carbon into the ecosystem, through photosynthesis. Part of…
Impacts of climate change on the performance of an insect pest and associated consequences for tritrophic interactions
2019
Global warming poses a major challenge to living organisms, particularly for ectothermic animals like insects, whose physiology and behaviour are closely related with direct thermal surroundings. This thesis aims at experimentally investigating the impacts of climate change on the overall performance of a major grapevine pest, the European grapevine moth (Lobesia botrana), and the associated consequences for interactions involving this phytophagous insect and adjacent trophic levels, more specifically natural enemies (parasitoids). The experiments conducted focus on three facets of climate change: an increase in mean temperature, an alteration of daily thermal range, and the occurrence of h…
Cropping system dynamics, climate variability, and seed losses among East African smallholder farmers: a retrospective survey.
2014
Abstract Climate variability directly affects traditional low input and rain-fed farming systems, but few studies have paid attention retrospectively to the cropping system’s ability to mitigate climate risk. This study analyzes the impacts of rainfall variability on farmers’ seed variety losses over time, considering changes in smallholder farming systems. The cropping system dynamics, in favoring maize at the expense of sorghum and pearl millet, have induced an increasing risk of seed loss during drought. Combining ecological anthropology and climatology, a retrospective survey asking farmers about the period 1961–2006 was carried out at three altitudinal levels (750, 950, and 1100 m) on …