Résumé
Atmospheric dioxygen (O2) concentration and isotopic composition are closely linked to the carbon cycle through anthropic carbon dioxide (CO2) emissions and biological processes such as photosynthesis and respiration. The measurement of the isotopic ratio of O2, trapped in ice core bubbles, brings information about past variation in the hydrological cycle at low latitudes, as well as past productivity. Currently, the interpretation of those variations could be drastically improved with a better (i.e., quantitative) knowledge of the oxygen isotopic fractionation that occurs during photosynthesis and respiration processes. This could be achieved, for example, during experiments using closed biological chambers. In order to estimate the isotopic fractionation coefficient with good precision, one of the principal limitations is the need for high-frequency online measurements of isotopic composition of O2, expressed as δ18O of O2 (δ18O(O2)) and O2 concentration. To address this issue, we developed a new instrument, based on the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, enabling high-temporal-resolution and continuous measurements of O2 concentration as well as δ18O(O2), both simultaneously. The minimum Allan deviation occurred between 10 and 20 min, while precision reached 0.002 % for the O2 concentration and 0.06 ‰ for δ18O(O2), which correspond to the optimal integration time and analytical precision before instrumental drift started degrading the measurements. Instrument accuracy was in good agreement with dual-inlet isotope ratio mass spectrometry (IRMS). Measured values were slightly affected by humidity, and we decided to measure δ18O(O2) and O2 concentration after drying the gas. On the other hand, a 1 % increase in O2 concentration increased the δ18O(O2) by 0.53 ‰. To ensure the good quality of O2 concentration and δ18O(O2) measurements we eventually proposed to measure the calibration standard every 20 min.
Auteurs, date et publication :
Auteurs Clément Piel , Daniele Romanini , Morgane Farradèche , Justin Chaillot , Clémence Paul , Nicolas Bienville , Thomas Lauwers , Joana Sauze , Kévin Jaulin , Frédéric Prié , Amaëlle Landais
Publication : Atmospheric Measurement Techniques
Date : 2024
Volume : 17
Issue : 22
Pages : 6647-6658
Catégorie(s)
#CNRS #Ecotron de MontpellierRésumé
Psychophysical work suggested that humans discriminate diel changes in natural soundscapes based on spectral cues. The present study extended this investigation by assessing human discrimination for diel variations in natural soundscapes using a database of scenes recorded in three distinct habitats (two temperate forests and a tropical forest) marginally affected by human activity and processed by a multi-band noise vocoder to degrade selectively spectral and temporal cues. The results confirm that auditory sensitivity to diel variations is high and is only affected by degradations to spectral cues. They also indicate that the resolution of these spectral cues depends on habitat.
Auteurs, date et publication :
Auteurs Karine Malysheva , Halyna Chernenko , Veronika Kondratieva , Anton Kurapov , Jérôme Sueur , Sylvain Haupert , Christian Lorenzi , Frédéric Apoux
Publication : JASA Express Letters
Date : 2025
Volume : 5
Issue : 10
Pages : 100001
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Tropical forest soils can act as sources or sinks of biogenic volatile organic compounds (BVOCs), especially terpenes, yet the impact of long-term nutrient deposition on these fluxes remains unclear. We aimed to assess how nitrogen (N), phosphorus (P), and combined (NP) fertilization affect soil-atmosphere terpene exchanges across seasons and topographical gradients in a tropical forest in French Guiana.
Auteurs, date et publication :
Auteurs Kaijun Yang , Joan Llusià , Zhaobin Mu , Jordi Sardans , Catherine Preece , Iolanda Filella , Romà Ogaya , Albert Gargallo-Garriga , Guille Peguero , Laëtitia M. Bréchet , Clément Stahl , Leandro Van Langenhove , Lore T. Verryckt , Helena Vallicrosa , Laura Márquez , Pere-Roc Fernández , Laynara Lugli , Yu Tan , Juxiu Liu , Ivan A. Janssens
Publication : Plant and Soil
Date : 2025
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Human-induced inputs of nitrogen (N) and phosphorous (P) disrupt global biogeochemical cycles and life itself. And yet there is no consensus on whether micro- or macronutrients are the main drivers of soil community assemblages. Tropical forests allow us to trace the response of nutrients on highly weathered soils, where previous studies have already shown N and P limitation. To address this, we conducted an N, P and NP field fertilization experiment in two French Guiana tropical rainforests (the Nouragues and Paracou forests) to study the response of metabarcoded ground-dwelling Hexapoda communities to macronutrients, while also assessing the impact of micronutrient availability (calcium (Ca), potassium (K), magnesium (Mg) and sodium (Na)). We assessed the importance of these nutrients through their impact on the abundance, richness, and composition of ground hexapod communities using linear models, canonical correlation analyses and analyses of variance. Our findings revealed that experimental fertilization with nitrogen and/or phosphorous did not drive ground hexapod community structure. In contrast, Ca, Mg and Na were positively associated with hexapod abundance. Ca, K and Mg positively correlated with OTU richness. And Ca and Na shaped community composition. Our results argue against the widespread assumption that macronutrient imbalances drive ground-dwelling hexapods, and we suggest that micronutrients need much more attention to properly assess the impact of nutrient imbalances and excessive fertilization in soils.
Auteurs, date et publication :
Auteurs Miquel Ferrín , Josep Peñuelas , Dolores Asensio , Laëtitia Bréchet , Pere Fernàndez , Lucia Fuchslueger , Albert Gargallo-Garriga , Laynara F. Lugli , Joan Llusià , Laura Márquez , Jérôme Murienne , Romà Ogaya , Jérôme Orivel , Jordi Sardans , Helena Vallicrosa , Ivan A. Janssens , Guille Peguero
Publication : Applied Soil Ecology
Date : 2026
Volume : 217
Pages : 106604
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Mayaro virus (MAYV), an alphavirus found in Latin America related to the chikungunya virus, is transmitted primarily by sylvatic Hemagogus mosquitoes. Sporadic cases have been reported in French Guiana, with notable outbreaks occurring in 2020. In this study, a cluster of MAYV infections observed among European researchers in French Guiana in early 2024 is described. The study included individuals who stayed at the Nouragues Nature Reserve between January 1 and February 28, 2024. The case definitions were based on clinical symptoms and virological tests (polymerase chain reaction or IgM serology). Complementary investigations in asymptomatic exposed individuals were also conducted. Six European individuals developed acute fever, polyarthralgia, headache, or rash. Polymerase chain reaction testing was used to confirm two cases, and serology was used to identify two probable cases. Symptoms resolved within weeks for most, but two cases had chronic arthralgia that lasted more than 3 weeks. In addition to the six symptomatic individuals, 13 people stayed for more than one night at the scientific station, and all were asymptomatic. Five of them underwent anti-MAYV IgM serological testing between 4 and 8 weeks after their stay, and all results were negative. Entomological investigations had revealed Hemagogus janthinomys, a MAYV vector, in the area just a few months before. The cluster highlights the potential for sylvatic MAYV outbreaks among visitors to the Amazon rainforest. These findings highlight the need for greater awareness of MAYV symptoms and the potential for underdiagnosis.
Auteurs, date et publication :
Auteurs Loïc Epelboin , Stanislas Talaga , Antoine Enfissi , Anissa Desmoulin , Cyril Gaertner , Maximilian Gertler , Jean-Bernard Duchemin , Paul Le Turnier , Dominique Rousset
Date : 2025
Catégorie(s)
#CNRS #FORET NouraguesRésumé
The 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.
Auteurs, date et publication :
Auteurs Gabriel Hes , Vincyane Badouard , Benoit Burban , Jocelyn Cazal , Elodie A. Courtois , Géraldine Derroire , Léa Francoise , Jean-Yves Goret , Ariane Mirabel , Petrus Naisso , Jérôme Ogée , Laetitia Proux , Elodie Schloesing , Sylvain Schmitt , Giacomo Sellan , Clément Stahl , Jérôme Chave
Publication : Scientific Reports
Date : 2025
Volume : 15
Issue : 1
Pages : 43423
Catégorie(s)
#CNRS #FORET NouraguesRésumé
Atmospheric dioxygen (O2) concentration and isotopic composition are closely linked to the carbon cycle through anthropic carbon dioxide (CO2) emissions and biological processes such as photosynthesis and respiration. The measurement of the isotopic ratio of O2, trapped in ice core bubbles, brings information about past variation in the hydrological cycle at low latitudes, as well as past productivity. Currently, the interpretation of those variations could be drastically improved with a better (i.e., quantitative) knowledge of the oxygen isotopic fractionation that occurs during photosynthesis and respiration processes. This could be achieved, for example, during experiments using closed biological chambers. In order to estimate the isotopic fractionation coefficient with good precision, one of the principal limitations is the need for high-frequency online measurements of isotopic composition of O2, expressed as δ18O of O2 (δ18O(O2)) and O2 concentration. To address this issue, we developed a new instrument, based on the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, enabling high-temporal-resolution and continuous measurements of O2 concentration as well as δ18O(O2), both simultaneously. The minimum Allan deviation occurred between 10 and 20 min, while precision reached 0.002 % for the O2 concentration and 0.06 ‰ for δ18O(O2), which correspond to the optimal integration time and analytical precision before instrumental drift started degrading the measurements. Instrument accuracy was in good agreement with dual-inlet isotope ratio mass spectrometry (IRMS). Measured values were slightly affected by humidity, and we decided to measure δ18O(O2) and O2 concentration after drying the gas. On the other hand, a 1 % increase in O2 concentration increased the δ18O(O2) by 0.53 ‰. To ensure the good quality of O2 concentration and δ18O(O2) measurements we eventually proposed to measure the calibration standard every 20 min.
Auteurs, date et publication :
Auteurs Clément Piel , Daniele Romanini , Morgane Farradèche , Justin Chaillot , Clémence Paul , Nicolas Bienville , Thomas Lauwers , Joana Sauze , Kévin Jaulin , Frédéric Prié , Amaëlle Landais
Publication : Atmospheric Measurement Techniques
Date : 2024
Volume : 17
Issue : 22
Pages : 6647-6658
Catégorie(s)
#CNRS #Ecotron de MontpellierRésumé
Atmospheric dioxygen (O2) concentration and isotopic composition are closely linked to the carbon cycle through anthropic carbon dioxide (CO2) emissions and biological processes such as photosynthesis and respiration. The measurement of the isotopic ratio of O2, trapped in ice core bubbles, brings information about past variation in the hydrological cycle at low latitudes, as well as past productivity. Currently, the interpretation of those variations could be drastically improved with a better (i.e., quantitative) knowledge of the oxygen isotopic fractionation that occurs during photosynthesis and respiration processes. This could be achieved, for example, during experiments using closed biological chambers. In order to estimate the isotopic fractionation coefficient with good precision, one of the principal limitations is the need for high-frequency online measurements of isotopic composition of O2, expressed as δ18O of O2 (δ18O(O2)) and O2 concentration. To address this issue, we developed a new instrument, based on the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, enabling high-temporal-resolution and continuous measurements of O2 concentration as well as δ18O(O2), both simultaneously. The minimum Allan deviation occurred between 10 and 20 min, while precision reached 0.002 % for the O2 concentration and 0.06 ‰ for δ18O(O2), which correspond to the optimal integration time and analytical precision before instrumental drift started degrading the measurements. Instrument accuracy was in good agreement with dual-inlet isotope ratio mass spectrometry (IRMS). Measured values were slightly affected by humidity, and we decided to measure δ18O(O2) and O2 concentration after drying the gas. On the other hand, a 1 % increase in O2 concentration increased the δ18O(O2) by 0.53 ‰. To ensure the good quality of O2 concentration and δ18O(O2) measurements we eventually proposed to measure the calibration standard every 20 min.
Auteurs, date et publication :
Auteurs Clément Piel , Daniele Romanini , Morgane Farradèche , Justin Chaillot , Clémence Paul , Nicolas Bienville , Thomas Lauwers , Joana Sauze , Kévin Jaulin , Frédéric Prié , Amaëlle Landais
Publication : Atmospheric Measurement Techniques
Date : 2024
Volume : 17
Issue : 22
Pages : 6647-6658
Catégorie(s)
#CNRS #Ecotron de MontpellierRésumé
Atmospheric dioxygen (O2) concentration and isotopic composition are closely linked to the carbon cycle through anthropic carbon dioxide (CO2) emissions and biological processes such as photosynthesis and respiration. The measurement of the isotopic ratio of O2, trapped in ice core bubbles, brings information about past variation in the hydrological cycle at low latitudes, as well as past productivity. Currently, the interpretation of those variations could be drastically improved with a better (i.e., quantitative) knowledge of the oxygen isotopic fractionation that occurs during photosynthesis and respiration processes. This could be achieved, for example, during experiments using closed biological chambers. In order to estimate the isotopic fractionation coefficient with good precision, one of the principal limitations is the need for high-frequency online measurements of isotopic composition of O2, expressed as δ18O of O2 (δ18O(O2)) and O2 concentration. To address this issue, we developed a new instrument, based on the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, enabling high-temporal-resolution and continuous measurements of O2 concentration as well as δ18O(O2), both simultaneously. The minimum Allan deviation occurred between 10 and 20 min, while precision reached 0.002 % for the O2 concentration and 0.06 ‰ for δ18O(O2), which correspond to the optimal integration time and analytical precision before instrumental drift started degrading the measurements. Instrument accuracy was in good agreement with dual-inlet isotope ratio mass spectrometry (IRMS). Measured values were slightly affected by humidity, and we decided to measure δ18O(O2) and O2 concentration after drying the gas. On the other hand, a 1 % increase in O2 concentration increased the δ18O(O2) by 0.53 ‰. To ensure the good quality of O2 concentration and δ18O(O2) measurements we eventually proposed to measure the calibration standard every 20 min.
Auteurs, date et publication :
Auteurs Clément Piel , Daniele Romanini , Morgane Farradèche , Justin Chaillot , Clémence Paul , Nicolas Bienville , Thomas Lauwers , Joana Sauze , Kévin Jaulin , Frédéric Prié , Amaëlle Landais
Publication : Atmospheric Measurement Techniques
Date : 2024
Volume : 17
Issue : 22
Pages : 6647-6658
Catégorie(s)
#CNRS #Ecotron de MontpellierRésumé
Atmospheric dioxygen (O2) concentration and isotopic composition are closely linked to the carbon cycle through anthropic carbon dioxide (CO2) emissions and biological processes such as photosynthesis and respiration. The measurement of the isotopic ratio of O2, trapped in ice core bubbles, brings information about past variation in the hydrological cycle at low latitudes, as well as past productivity. Currently, the interpretation of those variations could be drastically improved with a better (i.e., quantitative) knowledge of the oxygen isotopic fractionation that occurs during photosynthesis and respiration processes. This could be achieved, for example, during experiments using closed biological chambers. In order to estimate the isotopic fractionation coefficient with good precision, one of the principal limitations is the need for high-frequency online measurements of isotopic composition of O2, expressed as δ18O of O2 (δ18O(O2)) and O2 concentration. To address this issue, we developed a new instrument, based on the optical-feedback cavity-enhanced absorption spectroscopy (OF-CEAS) technique, enabling high-temporal-resolution and continuous measurements of O2 concentration as well as δ18O(O2), both simultaneously. The minimum Allan deviation occurred between 10 and 20 min, while precision reached 0.002 % for the O2 concentration and 0.06 ‰ for δ18O(O2), which correspond to the optimal integration time and analytical precision before instrumental drift started degrading the measurements. Instrument accuracy was in good agreement with dual-inlet isotope ratio mass spectrometry (IRMS). Measured values were slightly affected by humidity, and we decided to measure δ18O(O2) and O2 concentration after drying the gas. On the other hand, a 1 % increase in O2 concentration increased the δ18O(O2) by 0.53 ‰. To ensure the good quality of O2 concentration and δ18O(O2) measurements we eventually proposed to measure the calibration standard every 20 min.
Auteurs, date et publication :
Auteurs Clément Piel , Daniele Romanini , Morgane Farradèche , Justin Chaillot , Clémence Paul , Nicolas Bienville , Thomas Lauwers , Joana Sauze , Kévin Jaulin , Frédéric Prié , Amaëlle Landais
Publication : Atmospheric Measurement Techniques
Date : 2024
Volume : 17
Issue : 22
Pages : 6647-6658