67 research outputs found
Relationships between hydraulic traits and habitat preference for six Acer species occurring in the French Alps
Xylem hydraulic properties and vulnerability to cavitation were studied in six Acer species which occur, in the French Alps, along a soil moisture gradient from the moist valleys to the drier mountain stands. The results obtained suggest that a relationship existed between hydraulic properties and the species moisture preference. Maples located in dry zones (A. opalus, A. monspessulanum) proved more resistant to drought-induced cavitation than species that occurred in an irrigated area (A. negundo, A. pseudoplatanus, A. platanoides, A. campestre). The most vulnerable species to cavitation (A. negundo, A. pseudoplatanus, A. platanoides, A. campestre) showed the highest hydraulic conductances, whereas more cavitation-resistant species (A. opalus, A. monspessulanum) had the lowest conductances. This suggests a tradeoff between hydraulic efficiency and cavitation vulnerability. The possible ecological significances of these data are discussed in relation to the distribution of Acer species in their natural habitats
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PMIP4-CMIP6: the contribution of the Paleoclimate Modelling Intercomparison Project to CMIP6
The goal of the Palaeoclimate Modelling Intercomparison Project (PMIP) is to understand the response of the climate system to changes in different climate forcings and to feedbacks. Through comparison with observations of the environmental impacts of these climate changes, or with climate reconstructions based on physical,
chemical or biological records, PMIP also addresses the issue of how well state-of-the-art models simulate climate changes. Palaeoclimate states are radically different from those of the recent past documented by the instrumental record and thus provide an out-of-sample test of the models used for future climate projections and
a way to assess whether they have the correct sensitivity to forcings and feedbacks. Five distinctly different periods have been selected as focus for the core palaeoclimate experiments that are designed to contribute to the objectives of the sixth phase of the Coupled Model Intercomparison Project (CMIP6). This manuscript describes
the motivation for the choice of these periods and the design of the numerical experiments, with a focus upon their novel features compared to the experiments performed in previous phases of PMIP and CMIP as well as the benefits of common analyses of the models across multiple climate states. It also describes the information
needed to document each experiment and the model outputs required for analysis and benchmarking
Drivers of Holocene palsa distribution in North America
Palsas and peat plateaus are climatically sensitive landforms in permafrost peatlands. Climate envelope models have previously related palsa/peat plateau distributions in Europe to modern climate, but similar bioclimatic modelling has not been attempted for North America. Recent climate change has rendered many palsas/peat plateaus in this region, and their valuable carbon stores, vulnerable. We fitted a binary logistic regression model to predict palsa/peat plateau presence for North America by relating the distribution of 352 extant landforms to gridded modern climate data. Our model accurately classified 85.3% of grid cells that contain observed palsas/peat plateaus and 77.1% of grid cells without observed palsas/peat plateaus. The model indicates that modern North American palsas/peat plateaus are supported by cold, dry climates with large seasonal temperature ranges and mild growing seasons. We used palaeoclimate simulations from a general circulation model to simulate Holocene distributions of palsas/peat plateaus at 500-year intervals. We constrained these outputs with timings of peat initiation, deglaciation, and postglacial drainage across the continent. Our palaeoclimate simulations indicate that this climate envelope remained stationary in western North America throughout the Holocene, but further east it migrated northwards during 11.5–6.0 ka BP. However, palsa extents in eastern North America were restricted from following this moving climate envelope by late deglaciation, drainage and peat initiation. We validated our Holocene simulations against available palaeoecological records and whilst they agree that permafrost peatlands aggraded earliest in western North America, our simulations contest previous suggestions that late permafrost aggradation in central Canada was climatically-driven
Hommage à Camille Peyre, décédé le 23 avril 2015, à l'âge de 76 ans
Michalet Richard, Peltier Jean-Paul. Hommage à Camille Peyre, décédé le 23 avril 2015, à l'âge de 76 ans. In: Ecologia mediterranea, tome 41 n°1, 2015. p. 91
Traitement de la schizophrénie (les antipsychotiques à l'officine)
DIJON-BU MĂ©decine Pharmacie (212312103) / SudocSudocFranceF
Hommage à Camille Peyre, décédé le 23 avril 2015, à l'âge de 76 ans
Michalet Richard, Peltier Jean-Paul. Hommage à Camille Peyre, décédé le 23 avril 2015, à l'âge de 76 ans. In: Ecologia mediterranea, tome 41 n°1, 2015. p. 91
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