Auteurs, date et publication :
Auteurs N. Baghdadi , G. le Maire , J. Bailly , K. Ose , Y. Nouvellon , M. Zribi , C. Lemos , R. Hakamada
Publication : IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Date : 2025
Volume : 99
Pages : 1610
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
Dès son introduction à Madagascar, Eucalyptus robusta a été retenu comme espèce de reboisement pour sa remarquable capacité d'adaptation. L'extension de sa plantation par les populations rurales a abouti à la création d'un massif de près de 140 000 hectares autour d'Antananarivo. Son bois est devenu la principale source d'énergie utilisée par les ménages urbains et ruraux malgaches. Mais aujourd'hui, la production durable de cette ressource est gravement menacée. Le marché déficitaire et la pauvreté des populations rurales amènent les propriétaires forestiers à exploiter leurs taillis avec des rotations de plus en plus courtes, parfois inférieures à 2 ans. Cette surexploitation induit un gaspillage des éléments minéraux qui ne sont pas compensés par des apports extérieurs de nutriments. La production de charbon de bois se poursuit à partir de meules traditionnelles dont le rendement pondéral n'est que de 10 % environ. Le doublement de ce rendement par des méthodes simples permettrait pourtant de diminuer les superficies de forêt exploitées chaque année. À 6 ans, l'accroissement moyen annuel en volume commercial bois fort sur écorce des taillis anciens est de 18,8 m 3 /ha/an. Les meilleures provenances importées récemment permettent de doubler le volume moyen individuel des arbres à 9 ans. Des vergers à graines ont été plantés avec plusieurs provenances de l'aire naturelle pour créer des variétés composites. Cependant, des fécondations préférentielles intra-provenances et des pollutions par le pollen extérieur affectent fortement la qualité des variétés produites. Pour l'extension du massif d'eucalyptus, les populations rurales continuent à utiliser des graines locales ou planter des sauvageons. Ces plantations en E. robusta devront continuer à produire du bois malgré les modifications biotiques et abiotiques déjà constatés à Madagascar. Face à ces changements, les technologies modernes peuvent aider la recherche forestière à proposer un système durable de production de bois énergie autour des grands centres urbains. Cela aurait pour effet de maintenir un revenu régulier participant à la survie des populations rurales. (Résumé d'auteur)
Auteurs, date et publication :
Auteurs D. Verhaegen , H. Randrianjafy , H. Rakotondraoelina , M.-C. Trendelenburg Rakotonirina , N. Andriamampianina , P. Montagne , A. Rasamindisa , G. Chaix , J.-P. Bouillet , J.-M. Bouvet
Publication : Bois et Forêts des Tropiques
Date : 2025
Issue : 320
Pages : 15-30
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs Bini D , Alcantara dos Santos C , Bouillet J P , De Morais Gonçalves J L , Bran Nogueira Cardoso E J
Publication : Applied soil ecology
Date : 2025
Volume : 63
Pages : 57-66
Catégorie(s)
#CIRAD #FORET Itatinga #INRAERésumé
The association of N-2-fixing species (NFS) could be an attractive option for achieving a sustainable increase of Eucalyptus plantations (EP) productivity through a positive balance between facilitative effects and competition between species. A randomised block design was replicated at four sites (Cenibra, USP, Suzano and IP) in Southern Brazil and at one site in Congo. The development of mono-specific stands of Acacia mangium (100A) and Eucalyptus grandis or urophylla x grandis (100E), was compared with N fertilisation treatment (100E + N) and with mixed-species plantations in a 1:1 ratio (50A:50E), and in an additive series with varying densities of acacia for the same density of eucalypt (25A:100E, 50A:100E, 100A:100E). The objectives were to assess the effect of mixtures on tree growth and stand production, and the behaviour of the two species in contrasting soil and climatic conditions. Tree growth was monitored over stand rotation and the biomass of aboveground tree components estimated at mid-rotation and at harvesting age. Eucalyptus height was 13% higher in Brazil than in Congo. Favourable ecological conditions in Congo and Cenibra led to 50% higher Acacia tree height than at the other sites. A depressive effect of Eucalyptus neighbour trees on Acacia height and circumference growth, lower in Congo than in Brazil, was observed in the mixtures from age 1-2 years onwards. Depressive effects of acacia on eucalypt height and circumference growth were low in USP, Suzano and IP, high in Cenibra, and not observed in Congo, in 50A:50E and 25A:100E. A positive though insignificant response to N fertilisation was only found in USP and Congo. Complementarity for light and soil resource capture between Eucalyptus and Acacia trees resulted in mean annual increments in total stand stemwood biomass (MAI) that were 7-15%, 6-12%, and 40% higher in the additive series than for 100E in Cenibra, LISP and Congo, respectively at mid-rotation. Whilst lasting complementarity and facilitation in Congo led to 17-34% higher MAI in mixtures than for 100E at harvesting age, MAIs were not significantly higher in mixtures than for 100E in Brazil. Mixed-species plantations of Eucalyptus and A. mangium might enhance aboveground stand production on poor nutrient soils in warm and humid tropical climates with low water limitations. (c) 2012 Elsevier B.V. All rights reserved.
Auteurs, date et publication :
Auteurs J.-P. Bouillet , J.-P. Laclau , J.-L. de Moraes Goncalves , M. Voigtlaender , J.-L. Gava , F.-P. Leite , R. Hakamada , L. Mareschal , A. Mabiala , F. Tardy , J. Levillain , P. Deleporte , D. Epron , Y. Nouvellon
Publication : Forest Ecology and Management
Date : 2013
Volume : 301
Pages : 89-101
Catégorie(s)
#CIRAD #FORET Itatinga #INRAEAuteurs, date et publication :
Auteurs A. Bar-Hen , J. Chadø euf , H. Dessard , P. Monestiez
Publication : Statistics and Computing
Date : 2013
Volume : 23
Issue : 3
Pages : 297–309
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Leaf mass per area (LMA) and leaf equivalent water thickness (EWT) are key leaf functional traits providing information for many applications including ecosystem functioning modeling and fire risk management. In this paper, we investigate two common conclusions generally made for LMA and EWT estimation based on leaf optical properties in the near-infrared (NIR) and shortwave infrared (SWIR) domains: (1) physically-based approaches estimate EWT accurately and LMA poorly, while (2) statistically-based and machine learning (ML) methods provide accurate estimates of both LMA and EWT. Using six experimental datasets including broadleaf species samples of >150 species collected over tropical, temperate and boreal ecosystems, we compared the performances of a physically-based method (PROSPECT model inversion) and a ML algorithm (support vector machine regression, SVM) to infer EWT and LMA based on leaf reflectance and transmittance. We assessed several merit functions to invert PROSPECT based on iterative optimization and investigated the spectral domain to be used for optimal estimation of LMA and EWT. We also tested several strategies to select the training samples used by the SVM, in order to investigate the generalization ability of the derived regression models. We evidenced that using spectral information from 1700 to 2400 nm leads to strong improvement in the estimation of EWT and LMA when performing a PROSPECT inversion, decreasing the LMA and EWT estimation errors by 55% and 33%, respectively. The comparison of various sampling strategies for the training set used with SVM suggests that regression models show limited generalization ability, particularly when the regression model is applied on data fully independent from the training set. Finally, our results demonstrate that, when using an appropriate spectral domain, the PROSPECT inversion outperforms SVM trained with experimental data for the estimation of EWT and LMA. Thus we recommend that estimation of LMA and EWT based on leaf optical properties should be physically-based using inversion of reflectance and transmittance measurements on the 1700 to 2400 nm spectral range.
Auteurs, date et publication :
Auteurs J. -B. Féret , G. le Maire , S. Jay , D. Berveiller , R. Bendoula , G. Hmimina , A. Cheraiet , J. C. Oliveira , F. J. Ponzoni , T. Solanki , F. de Boissieu , J. Chave , Y. Nouvellon , A. Porcar-Castell , C. Proisy , K. Soudani , J. -P. Gastellu-Etchegorry , M. -J. Lefèvre-Fonollosa
Publication : Remote Sensing of Environment
Date : 2019
Volume : 231
Pages : 110959
Catégorie(s)
#ANR-Citation #CIRAD #CNRS #FORET ItatingaAuteurs, date et publication :
Auteurs Quentin Molto , Vivien Rossi , Lilian Blanc , Robert Freckleton
Publication : Methods in Ecology and Evolution
Date : 2013
Volume : 4
Issue : 2
Pages : 175–183
Catégorie(s)
#CIRAD #FORET ParacouRésumé
entropart is a package for R designed to estimate diversity based on HCDT entropy or similarity-based entropy. It allows calculating species-neutral, phylogenetic and functional entropy and diversity, partitioning them and correcting them for estimation bias.
Auteurs, date et publication :
Auteurs Eric Marcon , Bruno Hérault
Publication : Journal of Statistical Software
Date : 2015
Volume : 67
Issue : 8
Pages : 1–26
Catégorie(s)
#CIRAD #FORET ParacouRésumé
We tested the hypothesis that trees have measurable effects on infiltrability, macroporosity, and pref- erential flows in agrosilvopastoral systems. Managing agricultural systems for water conservation is a critical component of sustainable systems. We investigated the relationship between infiltrability and the distance to the nearest tree, and whether differences in macroporosity can account for differences in infiltrability. In both systems, preferential soil water flows were dominant compared to matrix flow. Trees in the pasture landscape improved infiltrability and preferential flow but had no significant effect in the coffee agroforestry system. After comparing rainfall intensity and frequency data to the measured infiltrability values, we conclude that trees in the pasture system reduce surface runoff at the highest observed rainfall intensities (>50 mm h − 1 ). The volcanic soils of the coffee plantation are less degraded and their high natural permeability has been maintained. Since the coffee plants at this site are established (40 years) perennial vegetation with substantial residues and extensive root systems like trees, they improve soil physical properties similarly to trees. Trees increase hydrologic services in pasture lands, a rapidly expanding land use type across Latin America, and therefore may be a viable land management option for mitigating some of the negative environmental impacts associated with land clearing and animal husbandry. However, in land manage- ment practices where understorey perennial vegetation makes up a large proportion of the cover, such as for coffee agroforestry systems, the effect of trees on infiltration-related ecosystem services could be less pronounced
Auteurs, date et publication :
Auteurs L. Benegas , U. Ilstedt , O. Roupsard , J. Jones , A. Malmer
Publication : Agriculture, Ecosystems & Environment
Date : 2025
Volume : 183
Pages : 185-196
Catégorie(s)
#CIRAD #FORET CoffeeFluxRésumé
A basic understanding of nutrition effects on the mechanisms involved in tree response to drought is essential under a future drier climate. A large-scale throughfall exclusion experiment was set up in Brazil to gain an insight into the effects of potassium (K) and sodium (Na) nutrition on tree structural and physiological adjustments to water deficit. Regardless of the water supply, K and Na supply greatly increased growth and leaf area index (LAI) of Eucalyptus grandis trees over the first 3yr after planting. Excluding 37% of throughfall reduced above-ground biomass accumulation in the third year after planting for K- supplied trees only. E.grandis trees were scarcely sensitive to drought as a result of the utilization of water stored in deep soil layers after clear-cutting the previous plantation. Trees coped with water restriction through stomatal closure (isohydrodynamic behavior), osmotic adjustment and decrease in LAI. Additionally, droughted trees showed higher phloem sap sugar concentrations. K and Na supply increased maximum stomatal conductance, and the high water requirements of fertilized trees increased water stress during dry periods. Fertilization regimes should be revisited in a future drier climate in order to find the right balance between improving tree growth and limiting water shortage.
Auteurs, date et publication :
Auteurs P. Battie-Laclau , J.-P. Laclau , J.-C. Domec , M. Christina , J.-P. Bouillet , M.-C. Piccolo , J.-L. de Moraes Goncalves , R. Moreira e Moreira , A.-V. Krusche , J.-M. Bouvet , Y. Nouvellon
Publication : New Phytologist
Date : 2014
Volume : 203
Issue : 2
Pages : 401-413