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| Author |
Marcon, E.; Herault, B. |
| Title |
Decomposing phylodiversity |
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Journal Article |
| Year |
2015 |
Publication |
Methods in Ecology and Evolution |
Abbreviated Journal |
Methods in Ecology and Evolution |
| Volume |
6 |
Issue |
3 |
Pages |
333-339 |
| Keywords |
Biodiversity; Entropy; Functional diversity; Phylogenetic diversity |
| Abstract |
Measuring functional or phylogenetic diversity is the object of an active literature. The main issues to address are relating measures to a clear conceptual framework, allowing unavoidable estimation-bias correction and decomposing diversity along spatial scales. We provide a general mathematical framework to decompose measures of species-neutral, phylogenetic or functional diversity into α and β components. We first unify the definitions of phylogenetic and functional entropy and diversity as a generalization of HCDT entropy and Hill numbers when an ultrametric tree is considered. We then derive the decomposition of diversity. We propose a bias correction of the estimates allowing meaningful computation from real, often undersampled communities. Entropy can be transformed into true diversity, that is an effective number of species or communities. Estimators of α- and β-entropy, phylogenetic and functional entropy are provided. Proper definition and estimation of diversity is the first step towards better understanding its underlying ecological and evolutionary mechanisms. © 2015 British Ecological Society. |
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Cirad, UMR EcoFoG, BP 709Kourou, French Guiana |
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Export Date: 31 March 2015 |
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EcoFoG @ webmaster @ |
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590 |
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Zhang, T.; Bai, S.-L.; Bardet, S.; Almeras, T.; Thibaut, B.; Beauchene, J. |
| Title |
Radial variations of vibrational properties of three tropical woods |
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Journal Article |
| Year |
2011 |
Publication |
Journal of Wood Science |
Abbreviated Journal |
J. Wood Sci. |
| Volume |
57 |
Issue |
5 |
Pages |
377-386 |
| Keywords |
Damping coefficient; Dynamic modulus; Extractives; Microfibril angle; Tropical woods |
| Abstract |
The radial trends of vibrational properties, represented by the specific dynamic modulus (E′/ρ) and damping coefficient (tan δ), were investigated for three tropical rainforest hardwood species (Simarouba amara, Carapa procera, and Symphonia globulifera) using free-free flexural vibration tests. The microfibril angle (MFA) was estimated using X-ray diffraction. Consistent patterns of radial variations were observed for all studied properties. E′/ρ was found to decrease from pith to bark, which was strongly related to the increasing pith-bark trend of MFA. The variation of tan δ along the radius could be partly explained by MFA and partly by the gradient of extractives due to heartwood formation. The coupling effect of MFA and extractives could be separated through analysis of the log(tan δ) versus log(E′/ρ) diagram. For the species studied, the extractive content putatively associated with heartwood formation generally tends to decrease the wood damping coefficient. However, this weakening effect of extractives was not observed for the inner part of the heartwood, suggesting that the mechanical action of extractives was reduced during their chemical ageing. © 2011 The Japan Wood Research Society. |
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CIRAD, UMR Ecofog, BP 701, 97387 Kourou Cedex, Guyane Française, France |
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14350211 (Issn) |
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Export Date: 26 October 2011; Source: Scopus; Coden: Jwscf; doi: 10.1007/s10086-011-1189-7; Language of Original Document: English; Correspondence Address: Bai, S.-L.; Department of Advanced Materials and Nanotechnology, College of Engineering, Peking University, Beijing 100871, China; email: slbai@pku.edu.cn |
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363 |
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Bossu, J.; Beauchene, J.; Estevez, Y.; Duplais, C.; Clair, B. |
| Title |
New insights on wood dimensional stability influenced by secondary metabolites: The case of a fast-growing tropical species Bagassa guianensis aubl |
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Journal Article |
| Year |
2016 |
Publication |
PLoS ONE |
Abbreviated Journal |
PLoS ONE |
| Volume |
11 |
Issue |
3 |
Pages |
e0150777 |
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Challenging evaluation of tropical forest biodiversity requires the reporting of taxonomic diversity but also the systematic characterization of wood properties in order to discover new promising species for timber industry. Among wood properties, the dimensional stability is regarded as a major technological characteristic to validate whether a wood species is adapted to commercial uses. Cell structure and organization are known to influence the drying shrinkage making wood density and microfibrils angle markers of choice to predict wood dimensional stability. On the contrary the role of wood extractive content remains unclear. This work focuses on the fast-growing tropical species Bagassa guianensis and we report herein a correlation between heartwood drying shrinkage and extractive content. Chemical extractions and shrinkage experiments were performed on separate wood twin samples to better evaluate correctly how secondary metabolites influence the wood shrinkage behaviour. Extractive content were qualitatively and quantitatively analysed using HPLC and NMR spectroscopy. We found that B guianensis heartwood has a homogeneous low shrinkage along its radius that could not be explained only by its basic density. In fact the low drying shrinkage is correlated to the high extractive content and a corrected model to improve the prediction of wood dimensional stability is presented. Additionally NMR experiments conducted on sapwood and heartwood extracts demonstrate that secondary metabolites biosynthesis occurs in sapwood thus revealing B. guianensis as a Juglans-Type heartwood formation. This work demonstrates that B. guianensis, a fast-growing species associated with high durability and high dimensional stability, is a good candidate for lumber production and commercial purposes. © 2016 Bossu et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
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Cirad, UMR EcoFoG, AgroParisTech, CNRS, INRA, Université des Antilles, Université de Guyane, Kourou, France |
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Export Date: 18 April 2016 |
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EcoFoG @ webmaster @ |
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673 |
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Goulamoussene, Y.; Bedeau, C.; Descroix, L.; Linguet, L.; Herault, B. |
| Title |
Environmental control of natural gap size distribution in tropical forests |
Type |
Journal Article |
| Year |
2017 |
Publication |
Biogeosciences |
Abbreviated Journal |
Biogeosciences |
| Volume |
14 |
Issue |
2 |
Pages |
353-364 |
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Natural disturbances are the dominant form of forest regeneration and dynamics in unmanaged tropical forests. Monitoring the size distribution of treefall gaps is important to better understand and predict the carbon budget in response to land use and other global changes. In this study, we model the size frequency distribution of natural canopy gaps with a discrete power law distribution. We use a Bayesian framework to introduce and test, using Monte Carlo Markov chain and Kuo-Mallick algorithms, the effect of local physical environment on gap size distribution. We apply our methodological framework to an original light detecting and ranging dataset in which natural forest gaps were delineated over 30 000 ha of unmanaged forest. We highlight strong links between gap size distribution and environment, primarily hydrological conditions and topography, with large gaps being more frequent on floodplains and in wind-exposed areas. In the future, we plan to apply our methodological framework on a larger scale using satellite data. Additionally, although gap size distribution variation is clearly under environmental control, variation in gap size distribution in time should be tested against climate variability. © Author(s) 2017. |
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Cirad, UMR EcoFoG, AgroParisTech, CNRS, Inra, Univ Antilles, Univ Guyane, Kourou, French Guiana |
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Export Date: 7 February 2017 |
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EcoFoG @ webmaster @ |
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729 |
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| Author |
Vincent, G.; Caron, F.; Sabatier, D.; Blanc, L. |
| Title |
LiDAR shows that higher forests have more slender trees |
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Journal Article |
| Year |
2012 |
Publication |
Bois et Forets des Tropiques |
Abbreviated Journal |
Bois Forets Tropiques |
| Volume |
66 |
Issue |
314 |
Pages |
51-56 |
| Keywords |
Competition; Fertility; French Guiana; LiDAR; Tree allometry |
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High-density Airborne Laser Scanning was used to derive the Canopy Height Model (CHM) of an experimental forest site in the neotropics (Paracou, French Guiana). Individual tree heights were computed by manually segmenting tree crowns on the CHM and then extracting the local maximum canopy height. Three hundred and ninety-six (396) height estimates were matched from dominant or emergent trees with the corresponding ground records of stem diameters sampled in two plots with different mean canopy heights (28.1 m vs. 31.3 m). Tree slenderness was found to be positively and very significantly correlated with mean canopy height at the plot level. The same correlation was observed at the species population level for the three species adequately sampled. It can therefore be concluded that stratification by canopy height is to be recommended when deriving allometric relationships in order to avoid bias in Above Ground Biomass estimations. |
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CIRAD, UMR Ecofog, 97300 Kourou, France |
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0006579x (Issn) |
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Export Date: 5 June 2013; Source: Scopus; Language of Original Document: English; Correspondence Address: IRD, UMR AMAP, 34000 Montpellier, France |
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EcoFoG @ webmaster @ |
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490 |
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Laybros, A.; Aubry-Kientz, M.; Féret, J.-B.; Bedeau, C.; Brunaux, O.; Derroire, G.; Vincent, G. |
| Title |
Quantitative airborne inventories in dense tropical forest using imaging spectroscopy |
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Journal Article |
| Year |
2020 |
Publication |
Remote Sensing |
Abbreviated Journal |
Remote Sens. |
| Volume |
12 |
Issue |
10 |
Pages |
1577 |
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Hyperspectral; LiDAR; Species diversity; Tropical forest; Cost effectiveness; Discriminant analysis; Infrared devices; Infrared radiation; Logistic regression; Remote sensing; Tropics; Classification accuracy; Classification performance; Linear discriminant analysis; Operational applications; Regularized discriminant analysis; Remote sensing technology; Short wave infrared bands; Visible and near infrared; Forestry |
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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). © 2020 by the authors. |
| Address |
Cirad, UMR EcoFoG (AgroParistech, CNRS, INRAE, Université des Antilles, Université de la Guyane), Kourou, French Guiana, 97379, France |
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Mdpi Ag |
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20724292 (Issn) |
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no |
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EcoFoG @ webmaster @ |
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969 |
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Sardans, J.; Urbina, I.; Grau, O.; Asensio, D.; Ogaya, R.; Peñuelas, J. |
| Title |
Long-term drought decreases ecosystem C and nutrient storage in a Mediterranean holm oak forest |
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Journal Article |
| Year |
2020 |
Publication |
Environmental and Experimental Botany |
Abbreviated Journal |
Environ. Exp. Bot. |
| Volume |
177 |
Issue |
104135 |
Pages |
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Aridity; Carbon stocks; Climate change; Nitrogen; Phosphorus; Potassium; Stoichiometry; carbon sequestration; deciduous forest; drought; experimental study; forest soil; long-term change; Mediterranean environment; net ecosystem exchange; nutrient cycling; shrub; stoichiometry; Mediterranean Sea; Phillyrea latifolia |
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Aridity has increased in recent decades in the Mediterranean Basin and is projected to continue to increase in the coming decades. We studied the consequences of drought on the concentrations, stoichiometries and stocks of carbon (C), nitrogen (N), phosphorus (P) and potassium (K) in leaves, foliar litter of a three dominant woody species and soil of a Mediterranean montane holm oak forest where soil-water content was experimentally reduced (15 % lower than the control plots) for 15 years. Nitrogen stocks were lower in the drought plots than in the control plots (8.81 ± 1.01 kg ha−1 in the forest canopy and 856 ± 120 kg ha−1 in the 0−15 cm soil layer), thus representing 7 and 18 % lower N stocks in the canopy and soil respectively. δ15N was consistently higher under drought conditions in all samples, indicating a general loss of N. Foliar C and K stocks were also lower but to a lesser extent than N. Decreases in biomass and C and N stocks due to drought were smallest for the most dominant tall shrub, Phillyrea latifolia, so our results suggest a lower capacity of this forest to store C and nutrients but also substantial resulting changes in forest structure with increasing drought. © 2020 Elsevier B.V. |
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Cirad, UMR EcoFoG (AgroParisTech, CNRS, Inra, Univ Antilles, Univ Guyane), Campus Agronomique, Kourou, 97310, French Guiana |
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Elsevier B.V. |
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00988472 (Issn) |
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EcoFoG @ webmaster @ |
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954 |
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Thevenin, J.-M.; Rossi, V.; Ducamp, M.; Doare, F.; Condina, V.; Lachenaud, P. |
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Numerous clones resistant to Phytophthora palmivora in the “Guiana” genetic group of Theobroma cacao L |
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Journal Article |
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2012 |
Publication |
PLoS ONE |
Abbreviated Journal |
PLoS ONE |
| Volume |
7 |
Issue |
7 |
Pages |
e40915 |
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Cocoa black pod rot, a disease caused by Stramenopiles of the genus Phytophthora, and particularly by the pan-tropical species P. palmivora, causes serious production losses worldwide. In order to reduce the impact of these pests and diseases, preference is given to genetic control using resistant varieties and, to that end, breeders seek sources of resistance in wild cocoa trees. For instance, surveys of spontaneous cocoa trees in French Guiana between 1985 and 1995 led to the collection of abundant plant material forming a particular genetic group (the “Guiana” group). Following numerous one-off studies demonstrating the merits of this group as a source of resistance to Phytophthora, this article presents the results of a comprehensive study assessing the resistance of 186 “Guiana” clones in relation to the Guianan strain (GY 27) of P. palmivora. This study, undertaken in French Guiana, using an efficient methodology (ten series of tests and a statistical test adapted to the ordinal nature of the data) confirmed that the “Guiana” genetic group does indeed constitute an important source of resistance to P. palmivora, though with some variations depending on the demes of origin. Numerous clones (59) proved to be as resistant as the SCAVINA 6 resistance control, whilst nine were statistically more resistant. The “Resistant” and “Moderately Resistant” Guianan clones totalled 108 (58% of the total tested). Some of the clones more resistant than SCAVINA 6 could be incorporated into numerous cocoa breeding programmes, particularly those that also display other notable qualities. The same applies for numerous other clones equivalent to SCAVINA 6, especially the “elite”' clones GU 134-B, GU 139-A and GU 285-A. © 2012 Thevenin et al. |
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CIRAD, UMR BGPI, Montpellier, France |
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19326203 (Issn) |
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Export Date: 16 August 2012; Source: Scopus; Art. No.: e40915; doi: 10.1371/journal.pone.0040915; Language of Original Document: English; Correspondence Address: Thevenin, J.-M.; CIRAD, UPR Bioagresseurs: Analyse et Maîtrise du Risque, Kourou, Guyane, France; email: jean-marc.thevenin@cirad.fr |
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EcoFoG @ webmaster @ |
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423 |
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Mathieu, A.; Letort, V.; Cournède, P.H.; Zhang, B.G.; Heuret, P.; De Reffye, P. |
| Title |
Oscillations in functional structural plant growth models |
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Journal Article |
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2012 |
Publication |
Mathematical Modelling of Natural Phenomena |
Abbreviated Journal |
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7 |
Issue |
6 |
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47-66 |
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Cecropia trees; Cucumber plant; Dynamic system of plant growth; Functional-structural plant models; GreenLab |
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The dynamic model of plant growth GreenLab describes plant architecture and functional growth at the level of individual organs. Structural development is controlled by formal grammars and empirical equations compute the amount of biomass produced by the plant, and its partitioning among the growing organs, such as leaves, stems and fruits. The number of organs initiated at each time step depends on the trophic state of the plant, which is evaluated by the ratio of biomass available in plant to the demand of all the organs. The control of the plant organogenesis by this variable induces oscillations in the simulated plant behaviour. The mathematical framework of the GreenLab model allows to compute the conditions for the generation of oscillations and the value of the period according to the set of parameters. Two case-studies are presented, corresponding to emergence of oscillations associated to fructification and branching. Similar alternating patterns are commonly reported by botanists. In this article, two examples were selected: alternate patterns of fruits in cucumber plants and alternate appearances of branches in Cecropia trees. The model was calibrated from experimental data collected on these plants. It shows that a simple feedback hypothesis of trophic control on plant structure allows the emergence of cyclic patterns corresponding to the observed ones. © EDP Sciences, 2012. |
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CIRAD, UMR AMAP, Montpellier, France |
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Export Date: 27 December 2012; Source: Scopus |
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EcoFoG @ webmaster @ |
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452 |
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Nicolini, E.; Caraglio, Y.; Pelissier, R.; Leroy, C.; Roggy, J.C. |
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Epicormic branches: a growth indicator for the tropical forest tree, Dicorynia guianensis Amshoff (Caesalpiniaceae) |
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Journal Article |
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2003 |
Publication |
Annals of Botany |
Abbreviated Journal |
Ann. Bot. |
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92 |
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1 |
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97-105 |
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Dicorynia guianensis; architecture; epicormic branch; primary growth; secondary growth; tropical forest; French Guiana; height : diameter ratio |
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Architectural analyses of temperate tree species using a chronological approach suggest that the expression of epicormic branches is closely related to low growth rates in the axes that make up the branching system. Therefore, sole consideration of epicormic criteria may be sufficient to identify trees with low secondary growth levels or with both low primary and secondary growth levels. In a tropical tree such as Dicorynia guianensis (basralocus), where chronological studies are difficult, this relationship could be very useful as an easily accessible indicator of growth potentials. A simple method of architectural tree description was used to characterize the global structure of more than 1650 basralocus trees and to evaluate their growth level. Measurements of simple growth characters [height, basal diameter, internode length of submittal part (top of the main axis of the tree)] and the observation of four structural binary descriptors on the main stem (presence of sequential branches and young epicormic branches, state of the submittal part, global orientation), indicated that epicormic branch formation is clearly related to a decrease in length of the successive growth units of the main stem. Analysis of height vs. diameter ratios among different tree subgroups, with and without epicormic branching, suggested that trees with epicormic branches generally have a low level of secondary growth compared with primary growth. (C) 2003 Annals of Botany Company. |
| Address |
Cirad, UMR AMAP, F-34398 Montpellier 05, France |
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OXFORD UNIV PRESS |
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0305-7364 |
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ISI:000183980200010 |
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EcoFoG @ eric.marcon @ |
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245 |
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