Résumé
Tropical soils are a major contributor to the balance of greenhouse gas (GHG) fluxes in the atmosphere. Models of tropical GHG fluxes predict that both the frequency of drought events and changes in atmospheric deposition of nitrogen (N) will significantly affect dynamics of soil carbon dioxide (CO2) and methane (CH4) production and consumption. In this study, we examined the combined effect of a reduction in precipitation and an increase in nutrient availability on soil CO2 and CH4 fluxes in a primary French Guiana tropical forest. Drought conditions were simulated by intercepting precipitation falling through the forest canopy with tarpaulin roofs. Nutrient availability was manipulated through application of granular N and / or phosphorus (P) fertilizer to the soil. Soil water content (SWC) below the roofs decreased rapidly and stayed at continuously low values until roof removal, which as a consequence roughly doubled the duration of the dry season. After roof removal, SWC slowly increased but remained lower than in the control soils even after 2.5 months of wet-season precipitation. We showed that drought-imposed reduction in SWC decreased the CO2 emissions (i.e CO2 efflux), but strongly increased the CH4 emissions. N, P and N × P (i.e. NP) additions all significantly increased CO2 emission but had no effect on CH4 fluxes. In treatments where both fertilization and drought were applied, the positive effect of N, P and NP fertilization on CO2 efflux was reduced. After roof removal, soil CO2 efflux was more resilient in the control plots than in the fertilized plots while there was only a modest effect of roof removal on soil CH4 fluxes. Our results suggest that a combined increase in drought and nutrient availability in soil can locally increase the emissions of both CO2 and CH4 from tropical soils, for a long term.
Auteurs, date et publication :
Auteurs Laëtitia Bréchet , Elodie A. Courtois , Thomas Saint-Germain , Ivan A. Janssens , Dolores Asensio , Irene Ramirez-Rojas , Jennifer L. Soong , Leandro Van Langenhove , Erik Verbruggen , Clément Stahl
Publication : Frontiers in Environmental Science
Date : 2025
Volume : 7
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Volatile terpenes are among the most diverse class of defensive compounds in plants, and they are implicated in both direct and indirect defense against herbivores. In terpenes, both the quantity and the diversity of compounds appear to increase the efficiency of defense as a diverse blend of compounds provides a more efficient protection against a broader range of herbivores and limits the chances that an enemy evolves resistance. Theory predicts that plant defensive compounds should be allocated differentially among tissues according to the value of the tissue, its cost of construction and the herbivore pressure on it. We collected volatile terpenes from bark and leaves of 178 individual tree belonging to 55 angiosperm species in French Guiana and compare the kind, amount, and diversity of compounds in these tissues. We hypothesized that in woody plants, the outermost part of the trunk should hold a more diverse blend of volatile terpenes. Additionally, as herbivore communities associated with the leaves is different to the one associated with the bark, we also hypothesized that terpene blends should be distinct in the bark vs. the leaves of a given species. We found that the mixture of volatile terpenes released by bark is different and more diverse than that released by leaves, both in monoterpenes and sesquiterpenes. This supports our hypothesis and further suggests that the emission of terpenes by the bark should be more important for trunk defense than previously thought.
Auteurs, date et publication :
Auteurs Elodie A. Courtois , Christopher Baraloto , C.E. Timothy Paine , Pascal Petronelli , Pierre-Alain Blandinieres , Didier Stien , Emeline Höuel , Jean-Marie Bessière , Jérôme Chave
Publication : Phytochemistry
Date : 2012
Volume : 82
Pages : 81–88
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Tropical rainforests harbor a particularly high plant diversity. We hypothesize that potential causes underlying this high diversity should be linked to distinct overall functionality (defense and growth allocation, anti-stress mechanisms, reproduction) among the different sympatric taxa. In this study we tested the hypothesis of the existence of a metabolomic niche related to a species-specific differential use and allocation of metabolites. We tested this hypothesis by comparing leaf metabolomic profiles of 54 species in two rainforests of French Guiana. Species identity explained most of the variation in the metabolome, with a species-specific metabolomic profile across dry and wet seasons. In addition to this “homeostatic” species-specific metabolomic profile significantly linked to phylogenetic distances, also part of the variance (flexibility) of the metabolomic profile was explained by season within a single species. Our results support the hypothesis of the high diversity in tropical forest being related to a species-specific metabolomic niche and highlight ecometabolomics as a tool to identify this species functional diversity related and consistent with the ecological niche theory.
Auteurs, date et publication :
Auteurs Albert Gargallo-Garriga , Jordi Sardans , Victor Granda , Joan Llusià , Guille Peguero , Dolores Asensio , Romà Ogaya , Ifigenia Urbina , Leandro Van Langenhove , Lore T. Verryckt , Jérome Chave , Elodie A. Courtois , Clément Stahl , Oriol Grau , Karel Klem , Otmar Urban , Ivan A. Janssens , Josep Peñuelas
Publication : Scientific Reports
Date : 2020
Volume : 10
Issue : 1
Pages : 6937
Catégorie(s)
#ANR-Citation #CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs J.-P. Laclau , J.-L. de Moraes Gonçalves , R. Moreira e Moreira , J.-P. Bouillet , Y. Nouvellon
Publication : Série Técnica IPEF
Date : 2025
Volume : 18
Issue : 39
Pages : 19625
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
The chemical investigations of Dicorynia guianensis heartwood led to the isolation of four new indole alkaloids for the first time in this plant. Compound (1) identified as spiroindolone 2′,3′,4′,9′-tetrahydrospiro [indoline-3,1′pyrido[3,4-b]-indol]-2-one, and compound (3) described as nitrone 1-methyl-4,9-dihydro-3H-pyrido [3,4-b] indole 2-oxide and were isolated for the first time as natural products. ABTS antioxidant activity guided their isolation.
Auteurs, date et publication :
Auteurs Jean-Baptiste Say Anouhe , Augustin Amissa Adima , Florence Bobelé Niamké , Didier Stien , Brise Kassi Amian , Pierre-Alain Blandinières , David Virieux , Jean-Luc Pirat , Seraphin Kati-Coulibaly , Nadine Amusant
Publication : Phytochemistry Letters
Date : 2015
Volume : 12
Pages : 158–163
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Sanna Olsson , Pedro Seoane-Zonjic , Rocío Bautista , M. Gonzalo Claros , Santiago C. González-Martínez , Ivan Scotti , Caroline Scotti-Saintagne , Olivier J. Hardy , Myriam Heuertz
Publication : Molecular Ecology Resources
Date : 2017
Volume : 17
Issue : 4
Pages : 614–630
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Barbara R. V. Meyer-Sand , Celine Blanc-Jolivet , Malte Mader , Kathelyn Paredes-Villanueva , Niklas Tysklind , Alexandre M. Sebbenn , Erwan Guichoux , Bernd Degen
Publication : Conservation Genetics Resources
Date : 2017
Pages : 1–3
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Clément Stahl , Bruno Hérault , Vivien Rossi , Benoit Burban , Claude Bréchet , Damien Bonal
Publication : Oecologia
Date : 2013
Volume : 173
Issue : 4
Pages : 1191–1201
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Elisa Adriano , Jean-Paul Laclau , João Domingos Rodrigues
Publication : Trees
Date : 2025
Volume : 31
Issue : 1
Pages : 285-297
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Understanding the mechanisms that drive the change of biotic assemblages over space and time is the main quest of community ecology. Assessing the relative importance of dispersal and environmental species selection in a range of organismic sizes and motilities has been a fruitful strategy. A consensus for whether spatial and environmental distances operate similarly across spatial scales and taxa, however, has yet to emerge. We used censuses of four major groups of organisms (soil bacteria, fungi, ground insects, and trees) at two observation scales (1-m2 sampling point vs. 2,500-m2 plots) in a topographically standardized sampling design replicated in two tropical rainforests with contrasting relationships between spatial distance and nutrient availability. We modeled the decay of assemblage similarity for each taxon set and site to assess the relative contributions of spatial distance and nutrient availability distance. Then, we evaluated the potentially structuring effect of tree composition over all other taxa. The similarity of nutrient content in the litter and topsoil had a stronger and more consistent selective effect than did dispersal limitation, particularly for bacteria, fungi, and trees at the plot level. Ground insects, the only group assessed with the capacity of active dispersal, had the highest species turnover and the flattest nonsignificant distance−decay relationship, suggesting that neither dispersal limitation nor nutrient availability were fundamental drivers of their community assembly at this scale of analysis. Only the fungal communities at one of our study sites were clearly coordinated with tree composition. The spatial distance at the smallest scale was more important than nutrient selection for the bacteria, fungi, and insects. The lower initial similarity and the moderate variation in composition identified by these distance-decay models, however, suggested that the effects of stochastic sampling were important at this smaller spatial scale. Our results highlight the importance of nutrients as one of the main environmental drivers of rainforest communities irrespective of organismic or propagule size and how the overriding effect of the analytical scale influences the interpretation, leading to the perception of greater importance of dispersal limitation and ecological drift over selection associated with environmental niches at decreasing observation scales.
Auteurs, date et publication :
Auteurs Guille Peguero , Miquel Ferrín , Jordi Sardans , Erik Verbruggen , Irene Ramírez-Rojas , Leandro Van Langenhove , Lore T. Verryckt , Jerome Murienne , Amaia Iribar , Lucie Zinger , Oriol Grau , Jerome Orivel , Clément Stahl , Elodie A. Courtois , Dolores Asensio , Albert Gargallo-Garriga , Joan Llusià , Olga Margalef , Romà Ogaya , Andreas Richter
Publication : Ecology
Date : 2025
Volume : 103
Issue : 2
Pages : e03599