Résumé
Several studies sustained the possibility that a photochemical reflectance index (PRI) directly obtained from satellite data can be used as a proxy for ecosystem light use efficiency (LUE) in diagnostic models of gross primary productivity. This modelling approach would avoid the complications that are involved in using meteorological data as constraints for a fixed maximum LUE. However, no unifying model predicting LUE across climate zones and time based on MODIS PRI has been published to date. In this study, we evaluate the effectiveness with which MODIS-based PRI can be used to estimate ecosystem light use efficiency at study sites of different plant functional types and vegetation densities. Our objective is to examine if known limitations such as dependence on viewing and illumination geometry can be overcome and a single PRI-based model of LUE (i.e. based on the same reference band) can be applied under a wide range of conditions. Furthermore, we were interested in the effect of using different faPAR (fraction of absorbed photosynthetically active radiation) products on the in-situ LUE used as ground truth and thus on the whole evaluation exercise. We found that estimating LUE at site-level based on PRI reduces uncertainty compared to the approaches relying on a maximum LUE reduced by minimum temperature and vapour pressure deficit. Despite the advantages of using PRI to estimate LUE at site-level, we could not establish an universally applicable light use efficiency model based on MODIS PRI. Models that were optimised for a pool of data from several sites did not perform well.
Auteurs, date et publication :
Auteurs A Goerner , M Reichstein , E Tomelleri , N Hanan , S Rambal , D Papale , D Dragoni , C Schmullius
Publication : Biogeosciences
Date : 2025
Volume : 8
Pages : 189-202
Catégorie(s)
#CNRS #FORET PuechabonAuteurs, date et publication :
Auteurs Sara Vicca , Manuela Balzarolo , Iolanda Filella , André Granier , Mathias Herbst , Alexander Knohl , Bernard Longdoz , Martina Mund , Zoltan Nagy , Krisztina Pintér , Serge Rambal , Jan Verbesselt , Aleixandre Verger , Achim Zeileis , Chao Zhang , Josep Peñuelas
Publication : Scientific Reports
Date : 2025
Volume : 6
Issue : 1
Catégorie(s)
#CNRS #FORET PuechabonRésumé
Intra-specific aggressive interactions play a prominent role in the life of many animals. While studies have found evidence for repeatability in boldness, activity, and exploration in amphibians, we know relatively little about consistent among-individual variation in aggressiveness, despite its importance for male-male competition and territoriality. Amphibians, and Neotropical poison frogs (Dendrobatidae) in particular, are highly suitable for investigating among-individual variation in aggressiveness, as most species exhibit strong territoriality in at least one of the sexes. In the present study, we aimed to fill this gap in knowledge, by investigating within- and between-individual variation in territorial aggression in a semi-natural population of the Neotropical poison frog Allobates femoralis (Dendrobatidae) in French Guiana. We conducted repeated, standardized behavioral tests to assess if the level of territorial aggression is consistent within and different between individuals. Further, we tested a possible link between body size and level of territorial aggression. We found moderate repeatability in territorial aggressiveness, but no link to age and/or body size. In conclusion, our study represents the first documentation of repeatable aggressive behavior in a territorial context in amphibians.
Auteurs, date et publication :
Auteurs Sarah Chaloupka , Mélissa Peignier , Susanne Stückler , Yimen Araya-Ajoy , Patrick Walsh , Max Ringler , Eva Ringler
Publication : Frontiers in Ecology and Evolution
Date : 2022
Volume : 10
Pages : 881387
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesRésumé
Longer-range movements of anuran amphibians such as mass migrations and habitat invasion have received a lot of attention, but fine-scale spatial behavior remains largely understudied. This gap is especially striking for species that show long-term site fidelity and display their whole behavioral repertoire in a small area. Studying fine-scale movement with conventional capture-mark-recapture techniques is difficult in inconspicuous amphibians: individuals are hard to find, repeated captures might affect their behavior and the number of data points is too low to allow a detailed interpretation of individual space use and time budgeting. In this study, we overcame these limitations by equipping females of the Brilliant-Thighed Poison Frog (Allobates femoralis) with a tag allowing frequent monitoring of their location and behavior. Neotropical poison frogs are well known for their complex behavior and diverse reproductive and parental care strategies. Although the ecology and behavior of the polygamous leaf-litter frog Allobates femoralis is well studied, little is known about the fine-scale space use of the non-territorial females who do not engage in acoustic and visual displays. We tracked 17 females for 6 to 17 days using a harmonic direction finder to provide the first precise analysis of female space use in this species. Females moved on average 1 m per hour and the fastest movement, over 20 m per hour, was related to a subsequent mating event. Traveled distances and activity patterns on days of courtship and mating differed considerably from days without reproduction. Frogs moved more on days with lower temperature and more precipitation, but mating seemed to be the main trigger for female movement. We observed 21 courtships of 12 tagged females. For seven females, we observed two consecutive mating events. Estimated home ranges after 14 days varied considerably between individuals and courtship and mating associated space use made up for ∼30% of the home range. Allobates femoralis females spent large parts of their time in one to three small centers of use. Females did not adjust their time or space use to the density of males in their surroundings and did not show wide-ranging exploratory behavior. Our study demonstrates how tracking combined with detailed behavioral observations can reveal the patterns and drivers of fine-scale spatial behavior in sedentary species.
Auteurs, date et publication :
Auteurs Marie-Therese Fischer , Max Ringler , Eva Ringler , Andrius Pašukonis , Nikolay Poyarkov
Publication : PeerJ
Date : 2025
Volume : 8
Pages : e8920
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Dinh Ho Tong Minh , Thuy Le Toan , Fabio Rocca , Stefano Tebaldini , Mauro Mariotti d'Alessandro , Ludovic Villard
Publication : IEEE Transactions on Geoscience and Remote Sensing
Date : 2025
Volume : 52
Issue : 2
Pages : 967-979
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Backgrounds and Aims Leaf functional traits have been used as a basis to categoize plants across a range of resource-use specialization, from those that conserv
Auteurs, date et publication :
Auteurs Fabrice Grassein , Servane Lemauviel-Lavenant , Sandra Lavorel , Michael Bahn , Richard D. Bardgett , Marie Desclos-Theveniau , Philippe Laîné
Publication : Annals of Botany
Date : 2015
Volume : 115
Issue : 1
Pages : 107-115
Catégorie(s)
#CNRS #Lautaret #UGARésumé
According to theories on cave adaptation, cave organisms are expected to develop a lower metabolic rate compared to surface organisms as an adaptation to food scarcity in the subterranean environments. To test this hypothesis, we compared the oxygen consumption rates of the surface and subterranean populations of a surface-dwelling species, the newt Calotriton asper, occasionally found in caves. In this study, we designed a new experimental setup in which animals with free movement were monitored for several days in a respirometer. First, we measured the metabolic rates of individuals from the surface and subterranean populations, both maintained for eight years in captivity in a natural cave. We then tested individuals from these populations immediately after they were caught and one year later while being maintained in the cave. We found that the surface individuals that acclimated to the cave significantly reduced their oxygen consumption, whereas individuals from the subterranean population maintained in the cave under a light/dark cycle did not significantly modify their metabolic rates. Second, we compared these metabolic rates to those of an obligate subterranean salamander (Proteus anguinus), a surface aquatic Urodel (Ambystoma mexicanum), and a fish species (Gobio occitaniae) as references for surface organisms from different phyla. As predicted, we found differences between the subterranean and surface species, and the metabolic rates of surface and subterranean C. asper populations were between those of the obligate subterranean and surface species. These results suggest that the plasticity of the metabolism observed in surface C. asper was neither directly due to food availability in our experiments nor the light/dark conditions, but due to static temperatures. Moreover, we suggest that this adjustment of the metabolic level at a temperature close to the thermal optimum may further allow individual species to cope with the food limitations of the subterranean environment.
Auteurs, date et publication :
Auteurs Olivier Guillaume , Marine Deluen , Allan Raffard , Olivier Calvez , Audrey Trochet
Publication : Ecology and Evolution
Date : 2025
Volume : 10
Issue : 23
Pages : 12983-12989
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENS #PLANAQUARésumé
Abstract
Animal personality traits are sometimes linked to an individual’s degree of plasticity, with certain personality types being more plastic than others. In territorial species, consistently high levels of aggression might increase the risk of harmful fights, while consistently low aggression might lead to the loss of a territory. Consequently, reacting plastically with an appropriate territorial response should be beneficial to avoid these risks. An integrative investigation of both personality traits and plasticity can help us better understand the dynamics of aggressive interactions during male-male competition. Here, we used a free-ranging Neotropical poison frog population to investigate the role of plasticity in male territorial aggression towards intruders. We conducted repeated standardized territorial intrusion experiments mimicking frogs of different body sizes via playback calls with different peak frequencies. We found individual repeatability for the latency to reach and approach a simulated intruder and observed that both aggressive and less aggressive males decreased their level of aggression towards big intruders. However, our results do not support a correlation between personality and plasticity in the context of male territory defense during the breeding season. We discuss how such a correlation between personality and plasticity might be conditional on the costs and benefits across contexts.
Auteurs, date et publication :
Auteurs Mélissa Peignier , Lauriane Bégué , Max Ringler , Birgit Szabo , Eva Ringler
Publication : Scientific Reports
Date : 2023
Volume : 13
Issue : 1
Pages : 3435
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Jerome Chave , D Navarrete , S Almeida , E Alvarez , Luiz EOC Aragão , Damien Bonal , P Châtelet , JE Silva-Espejo , J-Y Goret , P von Hildebrand
Publication : Biogeosciences
Date : 2025
Volume : 7
Issue : 1
Pages : 43-55
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Leandro Van Langenhove , Thomas Depaepe , Sara Vicca , Joke van den Berge , Clement Stahl , Elodie Courtois , James Weedon , Ifigenia Urbina , Oriol Grau , Dolores Asensio
Publication : Plant and Soil
Date : 2025
Pages : 1-18