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On the performance of radiocarbon and quartz OSL dating in macrotidal estuarine environments: Four case studies from Western France
No full textInternational audienceThe study of estuarine sedimentary archives provides valuable insights into their geomorphological evolution over the past two centuries, enhancing our understanding of estuarine responses to climate change. Establishing a reliable and precise geochronological framework is therefore essential for monitoring these changes. This study evaluates the performance of quartz Single-Aliquot Regenerative (SAR) OSL and AMS 14C dating in four estuaries along the western coast of France. The results are compared with cartographic data, serving as an independent age control. Of the 14 OSL dated samples, 10 yield depositional ages consistent with cartographic data, whereas the remaining 4 appear to overestimate ages by 20–100 years. In contrast, AMS 14C dating reveals numerous stratigraphic inversions, with at least 12 out of the 16 measured samples overestimating the depositional age in some cases by up to 5000 years, in total disagreement with cartographic data. The discrepancy between the OSL and radiocarbon ages reflects the constant reworking of allochthonous material, to which is added the further uncertainty associated with the local reservoir age. These factors fundamentally limit the reliability of 14C dating regardless of the material analyzed. By contrast, the OSL signal displays remarkable resilience, with any age overestimation linked to partial bleaching remaining minor (on the order of decades) compared with the errors affecting 14C ages. This underscores the capacity of OSL dating to resolve short-term environmental changes and positions it as the most reliable tool for constructing high-resolution chronologies of the last centuries in macrotidal estuarine settings
Le genre Chlorophytum Ker Gawl. (Asparagales, Asparagaceae) à Madagascar, avec la description de 12 nouvelles espèces, 4 nouvelles sous-espèces et 1 nouvelle variété
No full textPignal M., Phillipson P.B. & Bardot-Vaucoulon M. 2025. The genus Chlorophytum Ker Gawl. (Asparagales, Asparagaceae) in Madagascar, with the description of 12 new species, 4 new subspecies and 1 new variety. European Journal of TaxonomyThe genus Chlorophytum Ker Gawl. (Asparagaceae) is revised taxonomically for Madagascar. It is a palaeotropical genus of more than 200 species, all of which are geophytes that are distributed throughout Africa, the Arabian Peninsula (Oman), Southeast Asia, the Indian subcontinent, China and Australia. We recognise 39 endemic taxa for Madagascar (30 species, 4 subspecies, 3 varieties and 2 potential species not formally named due to incomplete material). Descriptions and geographical data are provided for all taxa, of which 17 are newly described in this revision: 12 species (C.Le genre Chlorophytum Ker Gawl (Asparagaceae) fait l'objet d'une révision taxonomique pour Madagascar. Il s'agit d'un genre paléotropical comptant plus de 200 espèces, toutes géophytes, réparties en Afrique, dans la péninsule arabique (Oman), en Asie du Sud.-Est., dans le sous-continent indien en Chine et en Australie. Nous reconnaissons 39 taxons endémiques à Madagascar (30 espèces, 4 sous-espèces 3 variétés et 2 espèces potentielles non nommées officiellement en raison d’un matériel incomplet). Les descriptions et les données géographiques sont fournies pour tous les taxons, dont 17 sont nouvellement décrits dans cette révision : 12 espèces, (C. albociliatum sp. nov., C. aspidistrifolium sp. nov., C. basivaginatum sp. nov., C. candelabrum sp. nov., C. darainense sp. nov., C. helvillae sp. nov., C. meridionale sp. nov., C. nigrogranulosum sp. nov., C. nusbaumeri sp. nov., C. ranirisonii sp. nov., C. ratovosonii sp. nov., C. tolyanum sp. nov.) ; 4 sous-espèces (C. sofiense subsp. gautieri subsp. nov., C. graniticum subsp. ambrense subsp. nov., C. meridionale subsp. ihoyense subsp. nov., C. meridionale subsp. tulearense subsp. nov.) et 1 variété. (C. madagascariense var. boinense var. nov.). Chlorophytum gramineum (Baker) H.Perrier, est basé sur un nom illégitime (Anthericum gramineum Baker), et est remplacé par le nom légitime postérieur, C. madagascariense Baker, que nous considérons comme un synonyme taxonomique. Nous conservons les variétés décrites par Perrier de la Bâthie au sein de cette espèce, en les transférant à C. madagascariense, et nous décrivons une variété supplémentaire : C. madagascariense var. pervillei. De plus, nous désignons un lectotype pour huit espèces C. decaryanum, C. decipiens, C. dianellifolium, C. geayanum, C. graniticum, C. namorokense H.Perrier, C. sofiense, C. subligulatum, et deux variétés : C. dianellifolium var. transiens et C. madagascariense var. sciaphilum comb. nov.) . Une clé d'identification et des évaluations préliminaires du statut de conservation selon les critères de la Liste rouge de l'UICN sont fournies pour toutes les espèces.Mots-clefs : Anthericum, Anthericaceae, Asparagacea
The BIOMASP+ project on biosphere-atmosphere exchanges and their role in air pollution in the subtropical megacity of São Paulo: motivations, methods and preliminary observations
No full textInternational audienceAir pollution, especially in urban areas, is the result of a complex mixture of natural and anthropogenic emissions and their atmospheric processing. It causes millions of premature deaths worldwide and affects plant metabolism, which in turn alters the emissions of Biogenic Volatile Organic Compound (BVOCs) by plants. By taking the subtropical Metropolitan Area of São Paulo (MASP) as a natural laboratory, the BIOMASP+ project (BIOsphere-atmosphere interactions in the Metropolitan Area of São Paulo - plus) a ims to evaluate the interplay between the biosphere and secondary pollution (ozone and SOA formation and aging). The Brazilian Atlantic Forest (Mata Atlântica) is the target ecosystem as the fifth biodiversity hotspot in the world. Here we present the scientific motivations of the project, its methodology and the preliminary observations from the Special Observation Periods of year 2023 (SOP1, 2, 3 and 4). BIOMASP+ is (i) integrative, by combining in-situ/remote/laboratory observations andmodeling, (ii) multidisciplinary, addressing micrometeorology, urban climate, atmospheric chemistry and biology. The project involves multiple nested scales: from leaf to above-canopy levels, from very short time (microseconds) to multi-year scale, from few millimeters (turbulence scale) to synoptic scale. In particular, the experimental effort relies on the implementation of two contrasting supersites (primary forest and urban forest) with a 30-m and 20-m flux towers, respectively, and a variety of state-of-the-art instruments. Ambient observations and the quantification of BVOC emissions have highlighted the complex interactions between meteorology, atmospheric composition of pollution, biogenic emissions of representative remnants of the Atlantic Forest and anthropogenic emissions
Synchronous Miocene radiations and geographic-dependent diversification of pantropical Xylopia (Annonaceae).
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Louis de Mas Latrie, historien de Chypre et de la Grèce franques: Actes du colloque organisé à Nicosie, Université de Chypre, 30-31 octobre 2024
No full textInternational audienceThis volume brings together the contributions presented at the colloquium in Nicosia dedicated to the founder of Cypriot medieval studies, Louis de Mas Latrie.Cet ouvrage réunit les contributions données à l'occasion du colloque de Nicosie consacré au fondateur de la médiévistique chypriote, Louis de Mas Latrie
L’État pharaonique: historiographie, pensée juridique, enjeux archéologiques et histoire sociale
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Holocene climatic changes in the Kerguelen archipelago (South Indian Ocean) based on marine and lacustrine palaeoclimatic archives
No full textInternational audienceClimatic variability in the Southern Hemisphere is largely controlled by the latitudinal position of the Southern Hemisphere Westerly Winds (SHW), whose migration influences precipitation, temperature, and Antarctic upwelling. This study presents the results of analyses of two lacustrine sediment cores from Lake Armor, located on the subantarctic Kerguelen Islands (49 • 15′S, 69 • 10′E), within the SHW belt. Lipid biomarkers (Glycerol Dialkyl Glycerol Tetraethers, n-alkanes, and their hydrogen isotopes) were used to reconstruct mean annual air temperature above freezing (MAF) and humidity conditions. These records are compared with a high-resolution diatom-based summer sea surface temperature (SST) reconstruction from marine core MD11-3353, situated 150 km southwest of Lake Armor. In the late glacial and Early Holocene, our results reveal a period of warm air temperature, comparable to current values and very warm sea surface temperature, 5°C above the current values. Around 9000 cal a BP, an abrupt transition occurred, marked by a cooling of 5°C in SST and 1.5°C in MAF, interpreted as a northward migration of the SHW and associated oceanic fronts. The Mid-to-Late Holocene period is characterized by pronounced MAF variability, including a notably warm interval between 3000 and 2000 cal a BP, when n-alkane dD suggests the prevalence of wetter conditions. Since ~250 cal a BP, a southward migration of the SHW has produced a 2.5°C rise in MAF. Our findings are overall consistent with previous studies from the Indian Ocean, but permit us to go a step further as by comparing SSTs and air temperatures. This suggests that SST is not a reliable predictor of air temperature on the Kerguelen Islands, particularly during the Early Holocene. We hence argue that Kerguelen air temperature is predominantly controlled by the position of westerly winds, as an indicator of reorganisations in air mass trajectories
Le genre Chlorophytum Ker Gawl. (Asparagales, Asparagaceae) à Madagascar, avec la description de 12 nouvelles espèces, 4 nouvelles sous-espèces et 1 nouvelle variété
No full textInternational audienceThe genus Chlorophytum Ker Gawl. (Asparagaceae) is revised taxonomically for Madagascar. It is a palaeotropical genus of more than 200 species, all of which are geophytes that are distributed throughout Africa, the Arabian Peninsula (Oman), Southeast Asia, the Indian subcontinent, China and Australia. We recognise 39 endemic taxa for Madagascar (30 species, 4 subspecies, 3 varieties and 2 potential species not formally named due to incomplete material). Descriptions and geographical data are provided for all taxa, of which 17 are newly described in this revision: 12 species (C. albociliatum sp. nov., C. aspidistrifolium sp. nov., C. basivaginatum sp. nov., C. candelabrum sp. nov., C. darainense sp. nov., C. helvillae sp. nov., C. meridionale sp. nov., C. nigrogranulosum sp. nov., C. nusbaumeri sp. nov., C. ranirisonii sp. nov., C. ratovosonii sp. nov., C. tolyanum sp. nov.); 4 subspecies (C. sofiense subsp. gautieri subsp. nov., C. graniticum subsp. ambrense subsp. nov., C. meridionale subsp. ihosyense subsp. nov., C. meridionale subsp. tulearense subsp. nov.); and 1 variety (C. madagascariense var. boinense var. nov.). Chlorophytum gramineum (Baker) H.Perrier, is based on an illegitimate name (Anthericum gramineum Baker), and is replaced by the later legitimate name, C. madagascariense Baker, that we consider to be a taxonomic synonym. We retain the varieties described by Perrier de la Bâthie within this species, transferring them to C. madagascariense, and we give a new name – C. madagascariense var. pervillei nom. nov. Furthermore, we lectotypify eight species: C. decaryanum, C. decipiens, C. dianellifolium, C. geayanum, C. graniticum, C. namorokense H.Perrier, C. sofiense, C. subligulatum, and two varieties: C. dianellifolium var. transiens and C. madagascariense var. sciaphilum comb. nov.). An identification key and preliminary conservation status assessments following IUCN Red List criteria are provided for all species
Early warfare in ancient Egypt, from the Predynastic to the First Intermediate Period (ca. 3500-2050 BC)
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Drivers of viral prevalence in landscape‐scale pollinator networks across Europe: honey bee viral density, niche overlap with this reservoir host and network architecture.
No full textInternational audienceViral transfer from managed pollinators potentially threatens wild pollinators and may be exacerbated by land‐use changes. Our causal models and plant‐pollinator network data from 48 European urban and agricultural landscapes revealed the ecological mechanisms underpinning viral transmission. Host identity, network architecture and land‐use modulated viral dynamics (black queen cell virus, BQCV; deformed wing virus, DWV‐A and DWV‐B). Viral prevalence in wild pollinators was driven by viral density in the reservoir host: honey bees, and secondarily by trophic niche overlap with these managed pollinators. Modular networks limited BQCV prevalence, which was driven by reduced honey bee niche overlap, suggesting minimal onward transmission among wild pollinators. Landscapes supporting greater wild pollinator abundance diluted DWV‐B transmission; in urban landscapes managed honey bees and wild pollinators experienced higher and lower BQCV prevalence, respectively. Disease in managed bee colonies and land‐use changes that concentrate pollinator foraging interactions present potential viral risks to wild pollinator health