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Liquid chromatography-ultraviolet-mass spectrometry analyses of hydroethanolic extracts of three wood species and their antioxidant and antifungal activities
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616222/)International audienceDegradation of wood and rot caused by wood-decaying fungi is a significant concern for countries such as Coˆte d'Ivoire, which has a substantial forest heritage. These pathogenic fungi have a negative effect on wood and other living organisms. Biological control agents could address environmental issues related to the large amount of wood waste in our environment and health issues linked to use of synthetic chemicals to combat wood-decaying fungi. This study examines the control of wood-destroying fungi Coniophora puteana, Pleurotus ostreatus, Poria placenta, Pycnoporus sanguineus, and Trametes versicolor using extracts from three durable woods of Coˆte d'Ivoire, Mansonia altissima (Bete), Milicia excelsa (Iroko), and Nauclea diderrichii (Badi). Wood sawdust comprises mixtures of sapwood and heartwood; for each wood species, evaluation of the hydroethanolic extracts obtained from sawdust with different sapwood : heartwood ratios is valuable. The studied sapwood–heartwood proportions were 5 percent : 95 percent, 15 percent : 85 percent, and 30 percent : 70 percent, with pure sapwood and pure heartwood extracts at 100 percent. Results showed that extracts from heartwood, sapwood, and sapwood–heartwood mixtures had fungicidal effects, with MFCs for Iroko of 1.25 mg mL 1 against C. puteana, P. ostreatus, and P. placenta. Bete extracts were more effective against P. sanguineus and T. versicolor, with minimum fungicidal concentrations of 4 mg mL 1 and 2.5 mg mL 1 , respectively. This study highlighted that the proportion of sapwood in sawdust (5%–30%), did not affect the fungicidal capacity or quality of the extracts. This research is of great significance for the large-scale valorization of wood sawdust and helps address a major environmental issue
Dynamics and environmental drivers of methane and nitrous oxide fluxes at the soil and ecosystem levels in a wet tropical forest
No full textInternational audienceTropical forests are critical for maintaining the global carbon balance and mitigating climate change, yet their exchange of greenhouse gases with the atmosphere remains understudied, particularly for methane (CH 4 ) and nitrous oxide (N 2 O). This study reports on continuous measurements of CH 4 and N 2 O fluxes at the ecosystem and soil levels, respectively through eddy covariance and an automated chamber technique, in a wet tropical forest in French Guiana over a period of 26 months. We studied the magnitude of CH 4 and N 2 O fluxes and their drivers (climatic variables) during the driest and wettest seasons. Seasonal ecosystem fluxes showed near-zero net CH 4 uptake during the driest season and emissions during the wettest season that were larger in magnitude than the uptake. Meanwhile, N 2 O emissions were of similar magnitudes in both seasons. Upland soils within the footprint of the eddy covariance tower emitted N 2 O in both seasons, although these fluxes were particularly small. In contrast, upland soils were characterised by CH 4 uptake. Overall, seasonal ecosystem and soil CH 4 and N 2 O fluxes were partially explained by seasonal variations in soil water content, soil temperature and global radiation. The magnitude and sign of the net ecosystem fluxes of CH 4 and N 2 O were likely due to outgassing from aboveground biomass and the presence of seasonally flooded areas within the footprint of the eddy covariance system. Further studies of other ecosystem compartments in different forest habitats are needed to better understand the temporal variations in CH 4 and N 2 O fluxes in wet tropical forests
Escaping a nomenclatural limbo caused by hybridization (and the challenges to measure it) in midwife toads (Alytidae: Alytes Wagler, 1829)
No full textInternational audienc
Environmental changes and risk of plague epidemics in Indonesia
No full textInternational audienceHistorical epidemiological data indicate that plague epidemics caused thousands of deaths in Indonesia between 1911 and 1956. During this period, silent phases of the disease were observed, followed by re-emergences several years or even decades later in certain regions. The Indonesian government, both at the regional and central levels (notably the Ministry of Health of the Republic of Indonesia), has undertaken decades of epidemic management efforts, including plague surveillance, medical treatments, vector control, and improvements in individual and environmental sanitation. There were a few sporadic outbreaks in 1968, 1987, and 2007. Since then, no further cases have occurred, but this could just be another silent phase. Methodology A literature search comprising articles and reports including published and unpublished dissertations, was performed using the PubMed online database, the Directorate General of Disease Prevention and Control, the Ministry of the Health Republic of Indonesia, Institute for Vector and Reservoir Control Research and Development, The Ministry of Health of Indonesia, Provincial Health Offices, Google Scholar, Science Direct, Medicus Index for the Southeast Asian Region (IMSEAR) and co.IMSEAR), and others. All literature referring to plague in Indonesia (1923–2019) was used as a reference for this article. The Global Land Cover 1992–2020 from the European Space Agency database was used to monitor land cover changes with a spatial resolution of 300 meters. The Esri Sentinel-2 Land Cover Explorer database, created by ESRI (Environmental Systems Research Institute, Redland, California, USA) using Sentinel-2 satellite imagery was also used. This database shows global land cover change between 2017 and 2023, using only 2023 data. Seven land cover classes were identified: Water, Forest, Flooded fields, Fields, Urban, Bare ground, and Pasture. Findings Environmental changes, essentially land conversion, have occurred in regions where plague outbreaks were previously recorded, with the exception of Eastern Java. Land conversion, increased human population density, and the heightened risk of human–rodent interactions could contribute to a resurgence of plague epidemics in Indonesia. Vectors and rodent hosts of Yersina pestis are still present in all regions but one with a higher human population density and thus a higher risk of contact. In Eastern Java, the environment remained the same as when plague outbreaks previously occurred. Conclusions We conclude that the historical areas of plague outbreaks have a potential for silent periods of plague transmission which could last decades. Furthermore, land conversion and the development of human settlements in these regions have led to a higher human presence, thus potentially increasing the risk of contact and transmission. There is therefore today a risk of plague resurgence in Indonesia and the current plague-free period might just be a silent period. In order to prevent outbreaks of plague after a period of silence and to implement an early alert system of plague transmission from animals to humans via fleas, the monitoring of potential Y. pestis circulation in sylvatic areas also needs to be intensified
Circulations, mobility, exchanges and transfers between French colonial women artistsand women artists from the colonies (Africa and Antilles) (1920-1950)
No full textInternational audienc
East Amazon forest understory temperatures reached a record high in 2023–2024
No full textInternational audienceThe Amazon forest was struck by an El Niño event with record heat and drought during the second semester 2023, and again in 2024. However, it remains unclear whether this extreme event impacted the forest understory because long-term in situ measurements are rare. Here, we present a time series of understory air temperatures over the 2014-2024 period based on a compilation of 114 ground-based measurements in the Eastern Amazon. We found that understory temperatures increased by up to 1.6 °C in 2023-2024 relative to the 2014-2022 reference period. Understory temperatures increased by 0.04 ± 0.03 °C/yr over 2014-2024, but this increasing trend was mostly driven by the 2023-2024 extreme event. For instance, hourly distributions were significantly warmer than the reference period, reaching + 25% during the 2024 wet season. Monthly mean understory air temperature ranged from 21 to 24 °C across sites, elevation being the main driver of this spatial variability. Using locally debiased ERA5-Land 2 m air temperature, we showed that forest canopies buffered monthly mean temperatures by -2.0 ± 0.5 °C and maximum temperatures by -4.6 ± 1 °C, albeit did not prevent the 2023-2024 anomaly. The observed increase by ~ 1 °C of understory air temperature in 2023-2024 relative to the 2014-2022 period constitutes a substantial perturbation of understory species' theoretical thermal niche, particularly threatening ectotherms.</div
L’espèce incertaine et les taxons flous
No full textInternational audienceLa « bonne » définition de l’espèce est régulièrement remise en question par les progrès des connaissances sur l’évolution et la spéciation. Cette question est loin d’être résolue parce que la spéciation est à l’œuvre dans la biodiversité actuelle et que les taxons de rang spécifique ne sont donc pas des espèces certaines, mais plutôt des hypothèses d’espèces qui doivent être testées. Darwin mettait déjà l’accent sur l’importance des « espèces douteuses » pour son argumentation sur la variation. Nous illustrons cette propriété du vivant à résister à la classification par l’exemple des taxons flous. Ceux-ci peuvent être résumés en deux grands types, le syngaméon et les espèces naissantes. La fréquence des flux de gènes entre taxons de rang spécifique, et le rôle écologique et évolutif de l’introgression, montrent que l’espèce incertaine constitue un aspect majeur des problématiques de la biodiversité
Les risques naturels à Mayotte dans le contexte du réchauffement climatique.
No full textPrésentation dans le cadre du COMEX « Gestion de crise et risque naturel » de l’association Mlézi Maore, Cavani, Mayotte
Ressources hydriques futures et sécheresses dans l’Atlas (Maroc) dans un scénario climatique à hautes émissions.
No full textInternational audienceUntersuchungsgebiet: Marokko, Nordafrika. Diese Studie untersucht 36 Gebirgs-Einzugsgebiete, die den Großteil des Oberflächenwassers des Landes bereitstellen.Ziel der Studie: Bewertung der potenziellen Auswirkungen des Klimawandels auf die Abflussverhältnisse in Marokko. Zwei hydrologische Modelle – World Wide HYPE und GR4J-CemaNeige – wurden in Kombination mit Ausgaben von neun bias-korrigierten regionalen Klimamodellen eingesetzt. Die zukünftigen Abflüsse wurden für ein Szenario mit hohen Emissionen (RCP8.5) für die Mitte des Jahrhunderts (2040–2060) und das Ende des Jahrhunderts (2070–2100) projiziert. Durch die Anwendung eines modernen Modellierungsansatzes an zahlreichen repräsentativen Standorten bietet die Studie einen robusten Rahmen zur Bewertung von Veränderungen hydrologischer Prozesse und der Wasserverfügbarkeit.Neue hydrologische Erkenntnisse für die Region: Die Ergebnisse zeigen deutliche Veränderungen in der Schneedynamik: Aufgrund steigender Temperaturen wird eine Abnahme des maximalen Schneespeichers um mehr als 50 % erwartet. Infolgedessen wird der Beitrag der Schneeschmelze zum Abfluss erheblich zurückgehen. Diese schneebedingten Veränderungen führen bis zum Ende des Jahrhunderts (2070–2100) zu einer durchschnittlichen Abflussreduktion von etwa −55 %. Diese Verringerung ist in erster Linie auf einen deutlichen Rückgang der Niederschläge (bis zu −43 %) in Verbindung mit einer starken Zunahme der potenziellen Evapotranspiration (bis zu +38 %) zurückzuführen. Darüber hinaus werden hydrologische Dürren häufiger und länger andauern, was die dringende Notwendigkeit von angepassten, einzugsspezifischen Wasserbewirtschaftungsstrategien unterstreicht.Study Region: Morocco, North Africa. This study examines 36 mountainous basins that supply most of the country's surface water. Study Focus: This study aims to evaluate the potential impacts of climate change on discharge in Morocco. Two hydrological models, World Wide HYPE and GR4J-CemaNeige, were used in combination with outputs from nine bias-corrected regional climate models. Future discharge was projected under the high-emission RCP8.5 scenario for the mid-century (2040-2060) and late-century (2070-2100). By implementing a state-of-the-art modeling approach on numerous representative sites, the study provides a robust framework for assessing changes in hydrological processes and water availability. New Hydrological Insights for the Region: This research identifies critical changes in snow dynamics, with peak snow storage projected to decrease by over 50 % due to rising temperatures. Consequently, the contribution of snowmelt to discharge will significantly diminish. These snow-related shifts are heading to an average reduction in discharge of − 55 % by the late century (2070-2100). This reduction is primarily driven by significant decreases in precipitation (up to − 43 %) combined with substantial increases in potential evapotranspiration (up to +38 %). Additionally, hydrological droughts are expected to become more frequent and prolonged, underscoring the urgent need for adaptive water management strategies specifically designed to address basin-specific characteristics.Région d’étude : Maroc, Afrique du Nord. Cette étude porte sur 36 bassins versants montagneux qui fournissent l’essentiel des ressources en eau de surface du pays.Objectif de l’étude : Évaluer les impacts potentiels du changement climatique sur les débits au Maroc. Deux modèles hydrologiques, World Wide HYPE et GR4J-CemaNeige, ont été utilisés en combinaison avec les sorties de neuf modèles climatiques régionaux corrigés du biais. Les débits futurs ont été projetés selon le scénario d’émissions élevées RCP8.5, pour la moitié du siècle (2040-2060) et la fin du siècle (2070-2100). En appliquant une méthodologie de modélisation de pointe sur un large ensemble de sites représentatifs, l’étude offre un cadre robuste pour évaluer les changements des processus hydrologiques et de la disponibilité en eau.Nouveaux éclairages hydrologiques pour la région : Cette recherche met en évidence des changements critiques dans la dynamique de la neige, avec une diminution de plus de 50 % du stockage neigeux maximal en raison de l’augmentation des températures. Par conséquent, l’apport de la fonte nivale aux débits diminuera fortement. Ces modifications liées à la neige devraient entraîner une réduction moyenne des débits d’environ −55 % d’ici la fin du siècle (2070-2100). Cette baisse est principalement due à une diminution marquée des précipitations (jusqu’à −43 %) combinée à une augmentation substantielle de l’évapotranspiration potentielle (jusqu’à +38 %). Par ailleurs, les sécheresses hydrologiques deviendront plus fréquentes et plus prolongées, soulignant l’urgence d’adopter des stratégies de gestion de l’eau adaptées aux spécificités de chaque bassin