Résumé
Multi-echo airborne laser scanner (ALS) has shown increasing utility for forestry applications in the two past decades. Among the numerous algorithms developed to process ALS data on forest environments some require to know actual sensor trajectory and deduced angles of incidence. However, sensor trajectory is not part of the ALS standard LAS file format and is often not delivered with point clouds. Scan angle is usually specified with a one byte precision or not given at all.This paper presents a method for the reconstruction of the sensor trajectory from a multi-echo ALS point cloud. It is based on the intersection of multi-echo pulses and was tested on three data sets acquired over a deciduous, a tropical and a mountainous forest, respectively. It allows sensor location estimate and scan angle estimate with less than 25 cm and 2-10-2° error.
Auteurs, date et publication :
Auteurs F. d Boissieu , M. Lang , J. Féret , J. Monnet , S. Durrieu
Date : 2019
Pages : 8964-8967
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Christopher Baraloto , Quentin Molto , Suzanne Rabaud , Bruno Hérault , Renato Valencia , Lilian Blanc , Paul V. A. Fine , Jill Thompson
Publication : Biotropica
Date : 2013
Volume : 45
Issue : 3
Pages : 288–298
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
The most unusual, and thus irreplaceable, functions performed by species in three different species-rich ecosystems are fulfilled by only the rare species in these ecosystems.
Auteurs, date et publication :
Auteurs David Mouillot , David R. Bellwood , Christopher Baraloto , Jerome Chave , Rene Galzin , Mireille Harmelin-Vivien , Michel Kulbicki , Sebastien Lavergne , Sandra Lavorel , Nicolas Mouquet , C. E. Timothy Paine , Julien Renaud , Wilfried Thuiller , Georgina M. Mace
Publication : PLoS Biology
Date : 2013
Volume : 11
Issue : 5
Pages : e1001569
Catégorie(s)
#CIRAD #CNRS #FORET Nouragues #FORET ParacouRésumé
Tree growth on weathered soils in lowland tropical forests is limited by low phosphorous (P) availability. However, nutrient manupulation experiments do not always increase the P content in these trees, which raises the question whether trees are taking up added P. In French Guianese lowland rainforest, we measured changes in nitrogen (N) and P availability before and up to two months after N and P fertilizer addition, in soils with intact root systems and in soils where roots and mycorrhizal fungi were excluded by root exclusion cylinders. When the root system was excluded, P addition increased P availability to a much greater extent and for a longer time than in soils with an intact root system. Soil N dynamics were unaffected by root presence/absence. These results indicate rapid P uptake, but not N uptake, by tree roots, suggesting a very effective P acquisition process in these lowland rainforests.
Auteurs, date et publication :
Auteurs Leandro Van Langenhove , Ivan A. Janssens , Lore Verryckt , Laetitia Brechet , Iain P. Hartley , Clement Stahl , Elodie Courtois , Ifigenia Urbina , Oriol Grau , Jordi Sardans , Guille Peguero , Albert Gargallo-Garriga , Josep Peñuelas , Sara Vicca
Publication : Soil Biology and Biochemistry
Date : 2020
Volume : 140
Pages : 107646
Catégorie(s)
#ANR-Citation #CIRAD #FORET ParacouRésumé
ABSTRACT Diclidurus scutatus is an aerial insectivore bat endemic of South America and considered rare throughout its distribution range. We present the first record of this species in Rondônia State, northern Brazil, expanding its distribution more than 1000 km into southwestern Amazonia. Including this record, D. scutatus is known for 20 localities from eight countries (Brazil, Colombia, Ecuador, French Guiana, Guyana, Peru, Suriname, Venezuela), and two biomes-Amazonia and Atlantic Forest.
Auteurs, date et publication :
Auteurs Roberto Leonan Morim Novaes , Vinícius Cardoso Claudio , Adriana Akemi Kuniy
Publication : Acta Amazonica
Date : 2017
Volume : 47
Issue : 4
Pages : 359–364
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Ivan Scotti , William Montaigne , Klára Cseke , Stéphane Traissac
Publication : Annals of Forest Science
Date : 2013
Volume : 70
Issue : 6
Pages : 631–635
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Key message: Positive radial trends in WSG were common among light-demanding species, and were mainly explained by radial shift in fiber and parenchyma traits. Abstract: Trees can modify their wood structure in response to changes in mechanical, hydraulic and storage demands during their life-cycles. Thus, examining radial variations in wood traits is important to expand our knowledge of tree functioning and species ecological strategies. Yet, several aspects of radial changes in wood functional traits are still poorly understood, especially in angiosperm trees from tropical humid forests. Here, we examined radial shifts in wood traits in trunks of tropical forest species and explored their potential ecological implications. We first examined radial variations in wood specific gravity (WSG). Then, we asked what anatomical traits drove radial variations in WSG, and whether WSG, vessel fraction and specific hydraulic conductivity vary independently from each other along the radius gradients. We measured WSG and eight wood anatomical traits, at different radial positions along the trunks, in 19 tree species with contrasting shade-tolerance from a lowland tropical forest in eastern Amazonia. Most species had significant radials shifts in WSG. Positive radial gradients in WSG (i.e., increments from pith to bark) were common among shade-intolerant species and were explained by different combinations of fiber and parenchyma traits, while negative radial shifts in WSG (e.g., decreases towards the bark) were present in shade-tolerants, but were generally weakly related to anatomical traits. We also found that, in general, WSG was unrelated to vessel fraction and specific hydraulic conductivity in any radial position. This study illustrates the contrasting radial variations in wood functional traits that occur in tree species from a humid lowland tropical forest. In particular, our results provide valuable insights into the anatomical traits driving WSG variations during tree development. These insights are important to expand our knowledge on tree ecological strategies by providing evidence on how wood allocation varies as trees grow, which in turn can be useful in studying trait-demography associations, and in estimating tree above-ground biomass.
Auteurs, date et publication :
Auteurs Andrés González-Melo , Juan Manuel Posada , Jacques Beauchêne , Romain Lehnebach , Sébastien Levionnois , Katherine Rivera , Bruno Clair
Publication : Trees - Structure and Function
Date : 2022
Volume : 36
Issue : 2
Pages : 569–581
Catégorie(s)
#CIRAD #FORET ParacouAuteurs, date et publication :
Auteurs Tian Zhang , Shu-Lin Bai , Sandrine Bardet , Tancrède Alméras , Bernard Thibaut , Jacques Beauchêne
Publication : Journal of Wood Science
Date : 2011
Volume : 57
Issue : 5
Pages : 377–386
Catégorie(s)
#CIRAD #FORET ParacouRésumé
Tropical forests have exceptional floristic diversity, but their characterization remains incomplete, in part due to the resource intensity of in-situ assessments. Remote sensing technologies can provide valuable, cost-effective, large-scale insights. This study investigates the combined use of airborne LiDAR and imaging spectroscopy to map tree species at landscape scale in French Guiana. Binary classifiers were developed for each of 20 species using linear discriminant analysis (LDA), regularized discriminant analysis (RDA) and logistic regression (LR). Complementing visible and near infrared (VNIR) spectral bands with short wave infrared (SWIR) bands improved the mean average classification accuracy of the target species from 56.1% to 79.6%. Increasing the number of non-focal species decreased the success rate of target species identification. Classification performance was not significantly affected by impurity rates (confusion between assigned classes) in the non-focal class (up to 5% of bias), provided that an adequate criterion was used for adjusting threshold probability assignment. A limited number of crowns (30 crowns) in each species class was sufficient to retrieve correct labels effectively. Overall canopy area of target species was strongly correlated to their basal area over 118 ha at 1.5 ha resolution, indicating that operational application of the method is a realistic prospect (R2 = 0.75 for six major commercial tree species).
Auteurs, date et publication :
Auteurs Anthony Laybros , Mélaine Aubry-Kientz , Jean-Baptiste Féret , Caroline Bedeau , Olivier Brunaux , Géraldine Derroire , Grégoire Vincent
Publication : Remote Sensing
Date : 2020
Volume : 12
Issue : 10
Pages : 1577
Catégorie(s)
#CIRAD #FORET ParacouRésumé
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