Auteurs, date et publication :
Auteurs Michelle L Hart , Laura L Forrest , James A Nicholls , Catherine A Kidner
Publication : Taxon
Date : 2025
Volume : 65
Issue : 5
Pages : 1081-1092
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Gerhard Gottsberger
Publication : Acta Botanica Brasilica
Date : 2025
Volume : 30
Issue : 2
Pages : 313-325
Catégorie(s)
#CNRS #FORET NouraguesAuteurs, date et publication :
Auteurs Ryan A St Laurent , Carlos GC Mielke
Publication : ZooKeys
Date : 2025
Issue : 566
Pages : 117
Catégorie(s)
#⛔ No DOI found #CNRS #FORET NouraguesRésumé
In alpine and arctic ecosystems, the snowpack has been shown to insulate soils from the winter climatic harshness. Ongoing climate change modifies snowpack quantity and quality, but the consequences of these changes on the soil functioning remain largely unknown. We benefited from a subalpine landscape of the French Alps where, 700 years ago, agricultural practices led to the formation of terraces. Subsequently, on each terrace, snow thickness patterns significantly differed between the bank and the front areas inducing strong divergence in their soil microclimatic conditions. Using this framework, we measured abundances and activities of nitrifiers and denitrifiers, together with a set of environmental variables, on three grassland terraces between December and May to test the following hypotheses: (i) soil N-related microbial abundances and activities are sensitive to soil microclimatic variations and differ along the terrace snow depth gradient during winter, (ii) a thicker snowpack favors higher abundances and activities, and (iii) the driving forces for nitrification and denitrification abundances and activities vary along the snow depth gradient. Our results showed significantly and changing N-related microbial activities and abundances during winter despite partly frozen soils, and suggested the selection and/or adaptation of psychrophilic microbial communities. Moreover, activities as well as abundances of nitrifiers and denitrifiers were significantly higher under a weak or absent snowpack during winter, and mostly related to soil water content and soil surface temperature according to our models. We suggest that strongly variable soil abiotic conditions at the front stations enabled the release of nutrients from soil organic and inorganic compounds favoring psychrophilic bacterial abundances and activities. Contrastingly, a thicker and permanent snowpack maintained circum-zero soil temperatures during winter which limited the microbial community's turnover and release of organic and inorganic N. This created N-limited conditions and N-competition between microbial populations resulting in lower abundances and activities. Overall, changes in the snowpack depth strongly affect the soil microbial functioning of subalpine grasslands with potential consequences on nutrient dynamic and other trophic levels.
Auteurs, date et publication :
Auteurs My-Dung Jusselme , Patrick Saccone , Lucie Zinger , Mathieu Faure , Xavier Le Roux , Nadine Guillaumaud , Lionel Bernard , Jean-Christophe Clement , Franck Poly
Publication : Soil Biology and Biochemistry
Date : 2025
Volume : 92
Pages : 27-37
Catégorie(s)
#CNRS #Lautaret #UGARésumé
1. Empirical evidence and modelling both suggest that global changes may lead to an increased dominance of lianas and thus to an increased prevalence of liana-infested forest formations in tropical forests. The implications for tropical forest structure and the carbon cycle remain poorly understood. 2. We studied the ecological processes underpinning the structure and dynamics of a liana-infested forest in French Guiana, using a combination of long-term surveys (tree, liana, seedling and litter-fall), soil chemical analyses and remote-sensing approaches (LiDAR and Landsat). 3. At stand scale and for adult trees, the liana-infested forest had higher growth, recruitment and mortality rates than the neighbouring high-canopy forest. Both total seedling density and tree seedling recruitment were lower in the liana-infested forest. Stand scale above-ground biomass of the liana-infested forest was 58% lower than in the high-canopy forest. 4. Above-ground net primary productivity (ANPP) was comparable in the liana-infested and high-canopy forests. However, due to more abundant leaf production, the relative contribution of fast turnover carbon pools to ANPP was larger in the liana-infested forest and the carbon residence time was half that of the high-canopy forest. 5. Although soils of the liana-infested forest were richer in nutrients, soil elemental ratios suggest that liana-infested forest and high-canopy forest soils both derive from the same geological substrate. The higher nutrient concentration in the liana-infested forest may therefore be the result of a release of nutrients from vegetation after a forest blowdown. 6. Using small-footprint LiDAR campaigns, we show that the overall extent of the liana-infested forest has remained stable from 2007 to 2012 but about 10% of the forest area changed in forest cover type. Landsat optical imagery confirms the liana-infested forest presence in the landscape for at least 25 years. 7. Synthesis. Because persistently high rates of liana infestation are maintained by the fast dynamics of the liana-infested forest, liana-infested forests here appear to be the result of an arrested tropical forest succession. If the prevalence of such arrested succession forests were to increase in the future, this would have important implications for the carbon sink potential of Amazonian forests.
Auteurs, date et publication :
Auteurs Blaise Tymen , Maxime Rejou-Mechain , James W. Dalling , Sophie Fauset , Ted R. Feldpausch , Natalia Norden , Oliver L. Phillips , Benjamin L. Turner , Jerome Viers , Jerome Chave
Publication : JOURNAL OF ECOLOGY
Date : 2016
Volume : 104
Issue : 1
Pages : 149-159
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesRésumé
Un ensemble coordonné de plateformes ouvertes la recherche internationale en écotoxicologie : Analyse et Expérimentation sur les Ecosystèmes – France. Colloque « Construire le réseau ANTIOPES 2.0 - La toxicologie et l’écotoxicologie prédictives : de l’appliqué à l’opérationnel »
Auteurs, date et publication :
Auteurs Christian Mougin , Didier Azam , Thierry Caquet , Nathalie Cheviron , Samuel Dequiedt , Jean-François Le Galliard , Olivier Guillaume , Sabine Houot , Gérard Lacroix , Francois Lafolie , Pierre-Alain Maron , Radika Michniewicz , Christian Pichot , Lionel Ranjard , Jacques Roy , Bernhard ZELLER , Jean Clobert , Andre Chanzy
Date : 2016
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENS #PLANAQUARésumé
Plant responses to natural enemies include formation of secondary metabolites acting as direct or indirect defenses. Volatile terpenes represent one of the most diverse groups of secondary metabolites. We aimed to explore evolutionary patterns of volatile terpene emission. We measured the composition of damage-induced volatile terpenes from 202 Amazonian tree species, spanning the angiosperm phylogeny. Volatile terpenes were extracted with solid-phase micro extraction and desorbed in a gas chromatography-mass spectrometry for compound identification. The chemical diversity of the terpene blend showed a strong phylogenetic signal as closely related species emitted a similar number of compounds. Closely related species also tended to have compositionally similar blends, although this relationship was weak. Meanwhile, the ability to emit a given compound showed no significant phylogenetic signal for 200 of 286 compounds, indicating a high rate of diversification in terpene synthesis and/or great variability in their expression. Three lineages (Magnoliales, Laurales, and Sapindales) showed exceptionally high rates of terpene diversification. Of the 70 compounds found in >10% of their species, 69 displayed significant correlated evolution with at least one other compound. These results provide insights into the complex evolutionary history of volatile terpenes in angiosperms, while highlighting the need for further research into this important class of compounds.
Auteurs, date et publication :
Auteurs Elodie A. Courtois , Kyle G. Dexter , Charles Eliot Timothy Paine , Didier Stien , Julien Engel , Christopher Baraloto , Jerome Chave
Publication : ECOLOGY AND EVOLUTION
Date : 2016
Volume : 6
Issue : 9
Pages : 2854-2864
Catégorie(s)
#ANR-Citation #CNRS #FORET NouraguesRésumé
Developing and improving methods to monitor forest carbon in space and time is a timely challenge, especially for tropical forests. The next European Space Agency Earth Explorer Core Mission BIOMASS will collect synthetic aperture radar (SAR) data globally from employing a multiple baseline orbit during the initial phase of its lifetime. These data will be used for tomographic SAR (TomoSAR) processing, with a vertical resolution of about 20m, a resolution sufficient to decompose the backscatter signal into two to three layers for most closed-canopy tropical forests. A recent study, conducted in the Paracou site, French Guiana, has already shown that TomoSAR significantly improves the retrieval of forest aboveground biomass (AGB) in a high biomass forest, with an error of only 10% at 1.5-ha resolution. However, the degree to which this TomoSAR approach can be transferred from one site to another has not been assessed. We test this approach at the Nouragues site in central French Guiana (ca 100km away from Paracou), and develop a method to retrieve the top-of-canopy height from TomoSAR. We found a high correlation between the backscatter signal and AGB in the upper canopy layer (i.e. 20–40m), while lower layers only showed poor correlations. The relationship between AGB and TomoSAR data was found to be highly similar for forests at Nouragues and Paracou. Cross validation using training plots from Nouragues and validation plots from Paracou, and vice versa, gave an error of 16–18% of AGB using 1-ha plots. Finally, using a high-resolution LiDAR canopy model as a reference, we showed that TomoSAR has the potential to retrieve the top-of-canopy height with an error to within 2.5m. Our analyses show that the TomoSAR-AGB retrieval method is accurate even in hilly and high-biomass forest areas and suggest that our approach may be generalizable to other study sites, having a canopy taller than 30m. These results have strong implications for the tomographic phase of the BIOMASS spaceborne mission.
Auteurs, date et publication :
Auteurs Dinh Ho Tong Minh , Thuy Le Toan , Fabio Rocca , Stefano Tebaldini , Ludovic Villard , Maxime Réjou-Méchain , Oliver L. Phillips , Ted R. Feldpausch , Pascale Dubois-Fernandez , Klaus Scipal , Jérôme Chave
Publication : Remote Sensing of Environment
Date : 2016
Volume : 175
Pages : 138–147
Catégorie(s)
#ANR-Citation #CIRAD #CNRS #FORET NouraguesRésumé
Fungi are the main organisms responsible for plant biomass degradation in soils. While many studies have evaluated the impact of tree species on the taxonomic diversity of soil fungi, very few of them have addressed their functional gene diversity. In the present study, we assessed the impact of tree species, differing with respect to litter quality, and sampling dates on the diversity of four expressed fungal gene families: one housekeeping gene used as taxonomic marker and three others encoding key enzymes implicated in lignocellulose degradation selected as functional markers. This was performed by the high throughput sequencing of gene-fragments amplified from forest soil mRNA using fungal specific primers. Messenger RNAs were extracted from 10 soil samples collected over two seasons in plots planted with either the conifer Picea abies or the angiosperm Fagus sylvatica in a common garden experiment. Independently of the gene-family, less than 20% of the fungal transcripts were identified in both forest types. For all four fungal gene-families, variance partitioning identified the tree species and its interaction with the sampling plot as the factors that contributed most to global gene diversity (between 29% and 32%), while the sampling dates accounted for less than 9%. Further analysis of the contribution of soil proprieties revealed that the tree species-generated C/N ratio is the most important factor driving functional gene distribution (between 6% and 29% of the variation explained). Similarly, for each fungal gene family, statistical analyses identified tree species as the main factor responsible for variations in similarity between samples (as estimated by the Bray-Curtis beta diversity index). These results highlight that tree species, differing with respect to litter quality, selected different soil fungal communities expressing different set of genes involved in plant organic matter degradation. (C) 2016 Elsevier Ltd. All rights reserved.
Auteurs, date et publication :
Auteurs Florian Barbi , Elsa Prudent , Laurent Vallon , Marc Buee , Audrey Dubost , Arnaud Legout , Roland Marmeisse , Laurence Fraissinet-Tachet , Patricia Luis
Publication : Soil Biology and Biochemistry
Date : 2016
Volume : 100
Pages : 149-159
Catégorie(s)
#CNRS #Ecotron IleDeFrance #ENS #FORET BreuilRésumé
The rapidly growing number of grassroots ecological research networks demonstrates that ecologists have embraced distributed data collection and experimentation as a new tool for addressing global questions. A clear advantage of these networks is the ability to gather data at larger spatial and temporal scales and at relatively lower cost than could be typically accomplished by a single research team. However, a challenge arising from this structure is the need to merge distributed datasets into a coherent whole. The Nutrient Network, a coordinated distributed experiment entering its tenth year of data collection, has records from over 90 sites worldwide to date. In this paper I present lessons learned about data management from this project, focusing on such issues as standardization, storage, updates, and distribution of data within the network. I provide a relational database schema and associated workflow that could be generalized to many distributed ecological experiments or networked data observatories, especially those with need for taxonomic reconciliation of species occurrences. The success of distributed data collection efforts, especially long-term networks, will be proportional to the ability to coordinate and effectively combine project datasets.
Auteurs, date et publication :
Auteurs Eric M. Lind
Publication : Ecological Informatics
Date : 2016
Volume : 36
Pages : 231-236