Résumé
Des essais de plantations forestières ont été menés en Guyane française depuis le début des années 1960 sur plus de 138 espèces (70 espèces natives et 68 espèces exotiques). Une étude récente sur la productivité de ces espèces en plantation (projet ForesTreeCulture, 2013-2015) a mis en avant le fort potentiel de production de trois espèces natives (Simarouba amara Aubl., Vochysia tomentosa (G. Mey.) DC., Bagassa guianensis (Aubl.)) et d'une espèce d'Afrique de l'Ouest (Tarrietia utilis Sprague) avec des volumes de bois produits supérieurs à 20 m3/ha/an. Cependant, les propriétés du bois de ces espèces commerciales ne sont connues qu'au travers d'arbres issus de forêt naturelle. Nous présentons les propriétés du bois de ces espèces en conditions de plantation – densité, retrait, élasticité, angle du fil, durabilité – et discutons de leurs potentiels et de leurs usages respectifs futurs. Une autre espèce, Cordia alliodora ((Ruiz et Pavon) Oken), a également été retenue bien qu'elle n'ait pas encore été plantée en Guyane française. Cette espèce, native de Guyane, est bien connue en Amérique latine pour son bois et son fort potentiel de croissance en milieu anthropisé. (Résumé d'auteur)
Auteurs, date et publication :
Auteurs Hélène Morel , Eric-André Nicolini , Julie Bossu , Lilian Blanc , Jacques Beauchêne
Publication : Bois et Forêts des Tropiques
Date : 2025
Volume : 334
Pages : 61–74
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Forests dominate carbon (C) exchanges between the terrestrial biosphere and the atmosphere on land. In the long term, the net carbon flux between forests and the atmosphere has been significantly impacted by changes in forest cover area and structure due to ecological disturbances and management activities. Current empirical approaches for estimating net ecosystem productivity (NEP) rarely consider forest age as a predictor, which represents variation in physiological processes that can respond differently to environmental drivers, and regrowth following disturbance. Here, we conduct an observational synthesis to empirically determine to what extent climate, soil properties, nitrogen deposition, forest age and management influence the spatial and interannual variability of forest NEP across 126 forest eddy-covariance flux sites worldwide. The empirical models explained up to 62% and 71% of spatio-temporal and across-site variability of annual NEP, respectively. An investigation of model structures revealed that forest age was adominant factor of NEP spatio-temporal variability in both space and time at the global scale as compared to abiotic factors, such as nutrient availability, soil characteristics and climate. These findings emphasize the importance of forest age in quantifying spatio-temporal variation in NEP using empirical approaches.
Auteurs, date et publication :
Auteurs S. Besnard , N. Carvalhais , M. A. Arain , A. Black , S. de Bruin , N. Buchmann , A. Cescatti , J. Q. Chen , Jgpw Clevers , A. R. Desai , C. M. Gough , K. Havrankova , M. Herold , L. Hortnagl , M. Jung , A. Knohl , B. Kruijt , L. Krupkova , B. E. Law , A. Lindroth
Publication : Environmental Research Letters
Date : 2018
Volume : 13
Issue : 12
Catégorie(s)
#CIRAD #FORET CoffeeFluxAuteurs, date et publication :
Auteurs Y. Nouvellon , J. P. Laclau , D. Epron , G. Le Maire , J. M. Bonnefond , L. M. J. Gonçalves , J. P. Bouillet
Publication : Tree Physiology
Date : 2025
Volume : 00
Pages : 1-16
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs Diarietou Sambakhe , Mathieu Fortin , Jean-Pierre Renaud , Christine Deleuze , Philippe Dreyfus , Nicolas Picard
Publication : Forest Science
Date : 2014
Volume : 60
Issue : 6
Pages : 1050–1059
Catégorie(s)
#CIRAD #FORET ParacouRésumé
We hypothesized that the nitrogen-fixing tree Acacia mangium could improve the growth and nitrogen nutrition of non-fixing tree species such as Eucalyptus. We measured the N-mineralization and respiration rates of soils sampled from plots covered with Acacia, Eucalyptus or native vegetation at two tropical sites (Itatinga in Brazil and Kissoko in the Congo) in the laboratory. We used a bioassay to assess N bioavailability to eucalypt seedlings grown with and without chemical fertilization for at least 6 months. At each site, Eucalyptus seedling growth and N bioavailability followed the same trends as the N-mineralization rates in soil samples. However, despite lower soil N-mineralization rates under Acacia in the Congo than in Brazil, Eucalyptus seedling growth and N bioavailability were much greater in the Congo, indicating that bioassays in pots are more accurate than N-mineralization rates when predicting the growth of eucalypt seedlings. Hence, in the Congo, planting Acacia mangium could be an attractive option to maintain the growth and N bioavailability of the non-fixing species Eucalyptus while decreasing chemical fertilization. Plant bioassays could help determine if the introduction of N-2-fixing trees will improve the growth and mineral nutrition of non-fixing tree species in tropical planted forests.
Auteurs, date et publication :
Auteurs Kittima Waithaisong , Agnes Robin , Louis Mareschal , Jean-Pierre Bouillet , Jean-Michel Harmand , Bruno Bordron , Jean-Paul Laclau , Jose Leonardo Moraes Goncalves , Claude Plassard
Publication : PLANTS-BASEL
Date : 2023
Volume : 12
Issue : 4
Catégorie(s)
#ANR-Citation #CIRAD #FORET ItatingaRésumé
Synthetic Aperture Radar (SAR) texture has been demonstrated to have the potential to improve forest biomass estimation using backscatter. However, forests are 3D objects with a vertical structure. The strong penetration of SAR signals means that each pixel contains the contributions of all the scatterers inside the forest canopy, especially for the P-band. Consequently, the traditional texture derived from SAR images is affected by forest vertical heterogeneity, although the influence on texture-based biomass estimation has not yet been explicitly explored. To separate and explore the influence of forest vertical heterogeneity, we introduced the SAR tomography technique into the traditional texture analysis, aiming to explore whether TomoSAR could improve the performance of texture-based aboveground biomass (AGB) estimation and whether texture plus tomographic backscatter could further improve the TomoSAR-based AGB estimation. Based on the P-band TomoSAR dataset from TropiSAR 2009 at two different sites, the results show that ground backscatter variance dominated the texture features of the original SAR image and reduced the biomass estimation accuracy. The texture from upper vegetation layers presented a stronger correlation with forest biomass. Texture successfully improved tomographic backscatter-based biomass estimation, and the texture from upper vegetation layers made AGB models much more transferable between different sites. In addition, the correlation between texture indices varied greatly among different tomographic heights. The texture from the 10 to 30 m layers was able to provide more independent information than the other layers and the original images, which helped to improve the backscatter-based AGB estimation.
Auteurs, date et publication :
Auteurs Zhanmang Liao , Binbin He , Xingwen Quan
Publication : International Journal of Applied Earth Observation and Geoinformation
Date : 2020
Volume : 88
Pages : 102049
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Climate change is expected to increase the frequency of droughts in most tropical regions in the coming decades. A passive phenomenon called hydraulic redistribution (HR) allows some plant species to take up water from deep and wet soil layers and redistribute it in the upper dry layers where other plants and soil biota can benefit from it. In addition, soil fertilization, particularly potassium (K), may also affect drought-adaptive mechanisms and increase water use efficiency (WUE) on poor and acidic tropical soils. The present study aimed at quantifying the role of HR and K fertilization on both wood productivity and WUE for stemwood production (WUEp) of Eucalyptus grandis plantations in Brazil under ambient and reduced (-37%) throughfall conditions. Tree transpiration was measured using trunk sap flow sensors over 21 months, and HR was estimated from the reverse sap flow (RF) observed in shallow roots over 18 months. Tree biomass, hydraulic conductance, soil water storage from surface to the water table (down to 17 m), and leaf photosynthetic capacity were also assessed. Significant HR was detected over the whole year, even during the rainy seasons. Neither potassium fertilization nor throughfall exclusion affected the velocity of water transported by HR, probably because most trees reached water table. Nonetheless, some photosynthetic capacity parameters, including the maximum photosynthetic rate (A(max)), increased in treatments with K addition. This higher A(max) combined with an increased sapwood area index, was associated with an increase in water uptake by 30 %-50 % and WUEp by 300% relative to K-deficient trees. We postulate that the increase in WUEp promoted by potassium fertilization was partly driven by an increase in biomass allocation to wood, at the expense of foraging organs (leaves and roots), because K addition alleviated constraints on light and water use. Our results indicate that fertilizing E. grandis plantations with K is beneficial to both wood biomass production and WUEp.
Auteurs, date et publication :
Auteurs Veronica Asensio , Jean-Christophe Domec , Yann Nouvellon , Jean-Paul Laclau , Jean-Pierre Bouillet , Lionel Jordan-Meille , Jose Lavres , Juan Delgado Rojas , Joannes Guillemot , Cassio H. Abreu-Junior
Publication : ENVIRONMENTAL AND EXPERIMENTAL BOTANY
Date : 2020
Volume : 176
Catégorie(s)
#ANR-Citation #CIRAD #FORET ItatingaAuteurs, date et publication :
Auteurs P. Battie Laclau , Delgado-Rojas J-S , Christina M , Nouvellon Y , Bouillet J-P , De Cassia Piccolo M , Moreira Marcelo Z , De Moraes Gonçalves J-L , Roupsard O , J.-P. Laclau
Publication : Forest Ecology and Management,
Date : 2025
Volume : 364
Pages : 77-89
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Potassium (K) is essential for a wide range of physiological functions in plants, and a limiting element for wood productivity in numerous forest ecosystems. However, the contribution of each of the K-sensitive physiological processes to the limitation of wood productivity is poorly known. In trees, K deficiency acts both on the source and the sinks of carbon making it difficult to disentangle its effects on wood productivity. Here, we review the literature dealing with the influence of K-limitation on tree physiological processes. Results from extensively studied tropical Eucalyptus plantations are used to illustrate the physiological processes the most impacted by K deficiency. We identify the main processes that limit the availability of K to the trees and influence the circulation of K ions in the ecosystem. Then, we describe the influence of K bioavailability on carbon assimilation, the water economy of trees, and carbon partitioning. We conclude this review by identifying the main priorities towards the process-based modelling of the influence of K on the carbon and water cycles in forest ecosystems. For each process modelling priority, we identify options that could be used in the current conceptual framework of most eco-physiological models.
Auteurs, date et publication :
Auteurs Ivan Cornut , Guerric Le Maire , Jean-Paul Laclau , Joannes Guillemot , Louis Mareschal , Yann Nouvellon , Nicolas Delpierre
Publication : FOREST ECOLOGY AND MANAGEMENT
Date : 2021
Volume : 494
Catégorie(s)
#ANR-Citation #CIRAD #FORET ItatingaRésumé
Tropical rainforests host exceptional biodiversity and provide important ecosystem services, but they are facing anthropogenic and climatic threats. Preserving the genetic diversity of forest tree populations is essential for their capacity to adapt and exhibit resilience to environmental changes and anthropogenic pressures. Here, we collected conservation genetic baseline information for the heavily exploited timber tree Dicorynia guianensis Amshoff (Fabaceae) at the regional and local levels in French Guiana. Based on genotyping at five microsatellite loci in 1566 individuals collected in 23 forest locations, we documented the genetic differentiation of locations from the West of French Guiana and identified distinctive genetic diversity patterns with higher genetic diversity and some bottlenecked sites in the East and inland. The regional population genetic structure is likely the result of past population isolation in distinct Pleistocene refuges and different demographic histories potentially influenced by Holocene drought periods or palaeofires. Assessment of spatial genetic structure (Sp from 0 to 0.028) in five intensively sampled locations yielded estimates of Wright’s neighborhood size of 35 to 313, indicative of restricted dispersal and local metapopulation dynamics, and useful as baseline information to assess the effects of selective logging for conservation management. These results support the current management strategies with low impact extraction of D. guianensis in three zones of the French Guiana permanent forest domain and allow us to make recommendations for further research and management to best preserve its genetic diversity and adaptive potential.
Auteurs, date et publication :
Auteurs Julien Bonnier , Niklas Tysklind , Valérie Troispoux , Ivan Scotti , Stéphanie Barthe , Olivier Brunaux , Stéphane Guitet , Stéphane Traissac , Myriam Heuertz
Publication : Tree Genetics & Genomes
Date : 2025
Volume : 20
Issue : 1
Pages : 2