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| Author |
Morel, H.; Mangenet, T.; Beauchene, J.; Ruelle, J.; Nicolini, E.; Heuret, P.; Thibaut, B. |
| Title |
Seasonal variations in phenological traits: leaf shedding and cambial activity in Parkia nitida Miq. and Parkia velutina Benoist (Fabaceae) in tropical rainforest |
Type |
Journal Article |
| Year |
2015 |
Publication |
Trees – Structure and Function |
Abbreviated Journal |
Trees – Structure and Function |
| Volume |
29 |
Issue |
4 |
Pages |
973-984 |
Keywords  |
Cambial activity; Climate; French Guiana; Leaf shedding pattern; Tropical rainforest |
| Abstract |
Key message: In French Guiana, the leaf and cambium phenologies should not be considered only as exogenous-driven processes, as the dry season, but also as endogenous-driven, as tree development stage. Abstract: Studies of the periodicity of wood formation provide essential data on tree age and on factors that control tree growth. The aim of this work was to investigate cambial phenology and its relation with leaf phenology and climatic seasonality in two briefly deciduous tropical rainforest species belonging to the genus Parkia. Wood microcores were collected every 15 days from April 2009 to February 2012 from five trees of each species. The microcores were stained with cresyl violet acetate to facilitate counting the number of cells in the cambial zone, in the radial enlargement zone and wall-thickening zone. At the same time, we observed leaf shedding pattern in the crown of the same trees. In both species, cambial activity was significantly reduced during the leafless period. In P. nitida, these two concomitant events were observed during the dry season whereas in P. velutina they can occur anytime in the year with no apparent link with seasonality. In conclusion, the period of reduced cambial activity in some tropical rainforest trees may be independent of rainfall seasonality and not necessarily follow an annual cycle. It appears that leaf phenology is a good proxy to estimate cambial activity. © 2015, Springer-Verlag Berlin Heidelberg. |
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CNRS, UMR Laboratoire de Mécanique et Génie Civil de Montpellier, Montpellier, France |
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Export Date: 16 July 2015 |
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EcoFoG @ webmaster @ |
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610 |
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Dutech, C.; Seiter, J.; Petronelli, P.; Joly, H.I.; Jarne, P. |
| Title |
Evidence of low gene flow in a neotropical clustered tree species in two rainforest stands of French Guiana |
Type |
Journal Article |
| Year |
2002 |
Publication |
Molecular Ecology |
Abbreviated Journal |
Mol. Ecol. |
| Volume |
11 |
Issue |
4 |
Pages |
725-738 |
| Keywords |
Caesalpiniaceae; gene flow; recolonization process; spatial genetic structure; tropical rainforest; Vouacapoua americana |
| Abstract |
The spatial genetic structure of the neotropical, clustered tree species Vouacapoua americana (Aublet) was studied in two natural forest stands (Paracou and Nouragues) in French Guiana. Using eight microsatellite loci, V. americana is characterized by a marked genetic structure at small spatial distances (under 30-60 m), in agreement with the limited seed dispersal by rodent species. Gene flow through pollen is also shown to be mainly restricted to less than 100 m. This result suggests that most pollination events (mediated through small insects) are probably limited to within-patches of individuals, which might explain the high genetic differentiation among patches (F-ST = 0.11) separated by less than 2 km. We also assume that stronger genetic structure in Paracou is likely to be due to lower seed dispersal by rodents, large spatial distances separating patches, or a recent recolonization event. |
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CNRS, Ctr Ecol Fonct & Evolut, F-34293 Montpellier 5, France, Email: jarne@cefe.cnrs-mop.fr |
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BLACKWELL PUBLISHING LTD |
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0962-1083 |
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ISI:000175250300008 |
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EcoFoG @ eric.marcon @ |
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248 |
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Barraza, F.; Schreck, E.; Lévêque, T.; Uzu, G.; Lopez, F.; Ruales, J.; Prunier, J.; Marquet, A.; Maurice, L. |
| Title |
Cadmium bioaccumulation and gastric bioaccessibility in cacao: A field study in areas impacted by oil activities in Ecuador |
Type |
Journal Article |
| Year |
2017 |
Publication |
Environmental Pollution |
Abbreviated Journal |
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| Volume |
229 |
Issue |
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Pages |
950-963 |
| Keywords |
Cacao; Cadmium; Ecuador; Health risk assessment; Uptake and bioaccumulation |
| Abstract |
Cacao from South America is especially used to produce premium quality chocolate. Although the European Food Safety Authority has not established a limit for cadmium (Cd) in chocolate raw material, recent studies demonstrate that Cd concentrations in cacao beans can reach levels higher than the legal limits for dark chocolate (0.8 mg kg−1, effective January 1st, 2019). Despite the fact that the presence of Cd in agricultural soils is related to contamination by fertilizers, other potential sources must be considered in Ecuador. This field study was conducted to investigate Cd content in soils and cacao cultivated on Ecuadorian farms in areas impacted by oil activities. Soils, cacao leaves, and pod husks were collected from 31 farms in the northern Amazon and Pacific coastal regions exposed to oil production and refining and compared to two control areas. Human gastric bioaccessibility was determined in raw cacao beans and cacao liquor samples in order to assess potential health risks involved. Our results show that topsoils (0–20 cm) have higher Cd concentrations than deeper layers, exceeding the Ecuadorian legislation limit in 39% of the sampling sites. Cacao leaves accumulate more Cd than pod husks or beans but, nevertheless, 50% of the sampled beans have Cd contents above 0.8 mg kg−1. Root-to-cacao transfer seems to be the main pathway of Cd uptake, which is not only regulated by physico-chemical soil properties but also agricultural practices. Additionally, natural Cd enrichment by volcanic inputs must not be neglected. Finally, Cd in cacao trees cannot be considered as a tracer of oil activities. Assuming that total Cd content and its bioaccessible fraction (up to 90%) in cacao beans and liquor is directly linked to those in chocolate, the health risk associated with Cd exposure varies from low to moderate. |
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Laboratoire des Sciences du Bois, UMR EcoFoG, ZI Pariacabo, Kourou, French Guiana |
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Cited By :1; Export Date: 4 June 2018 |
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no |
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EcoFoG @ webmaster @ |
Serial |
806 |
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Bonal, D.; Born, C.; Brechet, C.; Coste, S.; Marcon, E.; Roggy, J.C.; Guehl, J.M. |
| Title |
The successional status of tropical rainforest tree species is associated with differences in leaf carbon isotope discrimination and functional traits |
Type |
Journal Article |
| Year |
2007 |
Publication |
Annals of Forest Science |
Abbreviated Journal |
Ann. For. Sci. |
| Volume |
64 |
Issue |
2 |
Pages |
169-176 |
| Keywords |
C-13; functional diversity; leaf gas exchange; species grouping; tropical rainforest |
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We characterised the among species variability in leaf gas exchange and morphological traits under controlled conditions of seedlings of 22 tropical rainforest canopy species to understand the origin of the variability in leaf carbon isotope discrimination (Delta) among species with different growth and dynamic characteristics (successional gradient). Our results first suggest that these species pursue a consistent strategy in terms of. throughout their ontogeny (juveniles grown here versus canopy adult trees from the natural forest). Second, leaf Delta was negatively correlated with WUE and N, and positively correlated with g(s), but among species differences in Delta were mainly explained by differences in WUE. Finally, species belonging to different successional groups display distinct leaf functional and morphological traits. We confirmed that fast growing early successional species maximise carbon assimilation with high stomatal conductance. In contrast, fast and slow growing late successional species are both characterised by low carbon assimilation values, but by distinct stomatal conductance and leaf morphological features. Along the successional gradient, these differences result in much lower Delta for the intermediate species (i.e. fast growing late successional) as compared to the two other groups. |
| Address |
INRA Kourou, UMR Ecol Forets Guyane, F-97387 Kourou, Guyane, France, Email: damien.bonal@kourou.cirad.fr |
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EDP SCIENCES S A |
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1286-4560 |
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ISI:000244438100006 |
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no |
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EcoFoG @ eric.marcon @ |
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169 |
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Christensen-Dalsgaard, K.K.; Ennos, A.R.; Fournier, M. |
| Title |
Changes in hydraulic conductivity, mechanical properties, and density reflecting the fall in strain along the lateral roots of two species of tropical trees |
Type |
Journal Article |
| Year |
2007 |
Publication |
Journal of Experimental Botany |
Abbreviated Journal |
J. Exp. Bot. |
| Volume |
58 |
Issue |
15-16 |
Pages |
4095-4105 |
| Keywords |
Buttress roots; Density; Hydraulic conductivity; Hydraulic-mechanical trade-offs; Modulus of elasticity; Tropical trees; Wood; Elastic moduli; Hydraulic conductivity; Wood; Buttress roots; Hydraulic-mechanical trade-offs; Tropical trees; Forestry; water; article; biomechanics; histology; legume; physiology; plant root; plant stem; tree; wood; Xylopia; Biomechanics; Fabaceae; Plant Roots; Plant Stems; Trees; Water; Wood; Xylopia; Conductivity; Elastic Strength; Forestry; Wood |
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Roots have been described as having larger vessels and so greater hydraulic efficiency than the stem. Differences in the strength and stiffness of the tissue within the root system itself are thought to be an adaptation to the loading conditions experienced by the roots and to be related to differences in density. It is not known how potential mechanical adaptations may affect the hydraulic properties of the roots. The change in strength, stiffness, conductivity, density, sapwood area, and second moment of area distally along the lateral roots of two tropical tree species in which the strain is known to decrease rapidly was studied and the values were compared with those of the trunk. It was found that as the strain fell distally along the roots, so did the strength and stiffness of the tissue, whereas the conductivity increased exponentially. These changes appeared to be related to differences in density. In contrast to the distal-most roots, the tissue of the proximal roots had a lower conductivity and higher strength than that of the trunk. This suggests that mechanical requirements on the structure rather than the water potential gradient from roots to branches are responsible for the general pattern that roots have larger vessels than the stem. In spite of their increased transectional area, the buttressed proximal roots were subjected to higher levels of stress and had a lower total conductivity than the rest of the root system. © 2007 The Author(s). |
| Address |
AgroParisTech, LERFOB, Ecole Nationale du Genie Rural, des Eaux et Forêts, 14 Avenue Girardet-CS 4216, 54000 Nancy Cedex, France |
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00220957 (Issn) |
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Cited By (since 1996): 6; Export Date: 22 October 2011; Source: Scopus; Coden: Jeboa; doi: 10.1093/jxb/erm268; PubMed ID: 18039738; Language of Original Document: English; Correspondence Address: Christensen-Dalsgaard, K.K.; University of Manchester, Faculty of Life Sciences, Jackson's Mill, Manchester M60 1QD, United Kingdom; email: karen@cd-mail.dk; Chemicals/CAS: water, 7732-18-5; Water, 7732-18-5 |
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no |
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EcoFoG @ webmaster @ |
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353 |
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Paine, C.E.T.; Harms, K.E.; Schnitzer, S.A.; Carson, W.P. |
| Title |
Weak competition among tropical tree seedlings: Implications for species coexistence |
Type |
Journal Article |
| Year |
2008 |
Publication |
Biotropica |
Abbreviated Journal |
Biotropica |
| Volume |
40 |
Issue |
4 |
Pages |
432-440 |
| Keywords |
Brosimum alicastrum; competitive irrelevance; maintenance of biodiversity; Matisia cordata; resource competition; Panama; Peru; Pouteria reticulata; zone of influence |
| Abstract |
The intensity of competition among forest tree seedlings is poorly understood, but has important ramifications for their recruitment and for the maintenance of species diversity. Intense competition among seedlings could allow competitively dominant species to exclude subordinate species. Alternatively, the low density and small stature of forest tree seedlings could preclude intense interseedling competition. In this case, other processes, such as size-asymmetric competition with adults, interactions with consumers, or neutral dynamics would prevail as those structuring the forest understory. We tested the intensity of, and potential for, intraspecific competition among tree seedlings of three species (Brosimum alicastrum, Matisia cordata, and Pouteria reticulata) in two Neotropical rain forests. We reduced stem densities by up to 90 percent and monitored individual growth and survival rates for up to 24 mo. Individual growth and survival rates were generally unrelated to stem density. Contrary to the predicted behavior of intensely competing plant populations, the distribution of individual heights did not become more left-skewed with time for any species, regardless of plot density; i.e., excesses of short, suppressed individuals did not accumulate in high-density plots. We further measured the overlap of zones of influence (ZOIs) to assess the potential for resource competition. Seedling ZOIs overlapped only slightly in extremely dense monodominant plots, and even less in ambient-density plots of mixed composition. Our results thus suggest that interseedling competition was weak. Given the low density of tree seedlings in Neotropical forests, we infer that resource competition among seedlings may be irrelevant to their recruitment. |
| Address |
[Paine, C. E. Timothy; Harms, Kyle E.] Louisiana State Univ, Dept Biol Sci, Baton Rouge, LA 70803 USA, Email: cetpaine@gmail.com |
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BLACKWELL PUBLISHING |
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0006-3606 |
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ISI:000257717500006 |
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no |
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EcoFoG @ eric.marcon @ |
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134 |
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Trzcinski, M.K.; Srivastava, D.S.; Corbara, B.; Dezerald, O.; Leroy, C.; Carrias, J.-F.; Dejean, A.; Céréghino, R.; Rudolf, V. |
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The effects of food web structure on ecosystem function exceeds those of precipitation |
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Journal Article |
| Year |
2016 |
Publication |
Journal of Animal Ecology |
Abbreviated Journal |
Journal of Animal Ecology |
| Volume |
85 |
Issue |
5 |
Pages |
1147-1160 |
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bromeliad; climate change; community interactions; drought; ecosystem function; French Guiana; invertebrates; micro-organisms; phytotelmata; precipitation |
| Abstract |
Ecosystems are being stressed by climate change, but few studies have tested food web responses to changes in precipitation patterns and the consequences to ecosystem function. Fewer still have considered whether results from one geographic region can be applied to other regions, given the degree of community change over large biogeographic gradients. We assembled, in one field site, three types of macroinvertebrate communities within water-filled bromeliads. Two represented food webs containing both a fast filter feeder–microbial and slow detritivore energy channels found in Costa Rica and Puerto Rico, and one represented the structurally simpler food webs in French Guiana, which only contained the fast filter feeder–microbial channel. We manipulated the amount and distribution of rain entering bromeliads and examined how food web structure mediated ecosystem responses to changes in the quantity and temporal distribution of precipitation. Food web structure affected the survival of functional groups in general and ecosystem functions such as decomposition and the production of fine particulate organic matter. Ecosystem processes were more affected by decreased precipitation than were the abundance of micro-organisms and metazoans. In our experiments, the sensitivity of the ecosystem to precipitation change was primarily revealed in the food web dominated by the single filter feeder–microbial channel because other top-down and bottom-up processes were weak or absent. Our results show stronger effects of food web structure than precipitation change per se on the functioning of bromeliad ecosystems. Consequently, we predict that ecosystem function in bromeliads throughout the Americas will be more sensitive to changes in the distribution of species, rather than to the direct effects caused by changes in precipitation. © 2016 The Authors. Journal of Animal Ecology © 2016 British Ecological Society |
| Address |
Boulevard de la Lironde, IRD, botAnique et bioinforMatique de l'Architecture des Plantes (UMR-IRD 123), TA A-51/PS2, Montpellier Cedex 5, France |
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Export Date: 1 September 2016 |
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no |
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EcoFoG @ webmaster @ |
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685 |
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Jabiol, J.; Corbara, B.; Dejean, A.; Cereghino, R. |
| Title |
Structure of aquatic insect communities in tank-bromeliads in a East-Amazonian rainforest in French Guiana |
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Journal Article |
| Year |
2009 |
Publication |
Forest Ecology and Management |
Abbreviated Journal |
For. Ecol. Manage. |
| Volume |
257 |
Issue |
1 |
Pages |
351-360 |
| Keywords |
Bromeliaceae; Classification; Community structure; Insects; Microcosms; Neural networks; Nouragues; Phytotelmata; Species richness |
| Abstract |
Tank-bromeliads are discrete habitats which contain distinct aquatic communities, and which commonly occur in the neotropics. Because they span a broad range of ecological gradients in terms of habitat structure and amount of resources, researchers study the associations between the biodiversity of communities and these gradients in rainforests, where the very high species richness and densities within other continuous habitats makes it difficult to quantify animal communities. We analysed the diversity of aquatic insect communities in relation to different tank-bromeliad species in a primary rainforest (French Guiana) using artificial intelligence and complex optimization techniques to classify communities and model their determinants. First, the self-organizing map (neural network) was used to classify 158 bromeliads according to the quantitative structure of the insect communities. Catopsis berteroniana and Guzmania lingulata formed separate clusters of plants on the virtual map, while Vriesea splendens, Vriesea pleiosticha and Aechmea melinonii were grouped together in the remaining clusters. Some insect taxa occurred in all bromeliads, while other taxa were specific to a given species. Second, general linear modelling allowed us to specify the influence of the bromeliad species; water volume and volume of fine particulate organic matter inside of the tank; elevation above the ground; and sampling site on taxonomic richness and insect abundance. The number of taxa and individuals per plant increased with greater water volume, but the slope of the relationships depended on the bromeliad species. The significant influence of bromeliad species suggested that at similar water volumes different plant species had different taxon richness and insect abundance. Greater amounts of fine particulate organic matter were detrimental to community diversity in the tanks, probably because they decreased available space by clogging it and/or affected oxygen concentrations. The influence of tank-bromeliad species on the aquatic insect community was primarily related to their physical (and probably chemical) features rather than to species-specific associations sensu stricto. The classification of bromeliads with respect to animal species is likely to provide referential schemes for those biodiversity patterns to be expected under certain conditions, and may help to target model communities for subsequent experimental research. (C) 2008 Elsevier B,V. All rights reserved. |
| Address |
[Jabiol, J.; Cereghino, R.] Univ Toulouse 3, Ecolab, Lab Ecol Fonctionnelle, CNRS,UMR 5245, F-31062 Toulouse 9, France, Email: cereghin@cict.fr |
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ELSEVIER SCIENCE BV |
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0378-1127 |
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ISI:000261856000038 |
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EcoFoG @ eric.marcon @ |
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124 |
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Sarmiento, C.; Patino, S.; Paine, C.E.T.; Beauchene, J.; Thibaut, A.; Baraloto, C. |
| Title |
Within-Individual Variation of Trunk and Branch Xylem Density in Tropical Trees |
Type |
Journal Article |
| Year |
2011 |
Publication |
American Journal of Botany |
Abbreviated Journal |
Am. J. Bot. |
| Volume |
98 |
Issue |
1 |
Pages |
140-149 |
| Keywords |
branch xylem density; French Guiana; functional trait; tropical trees; trunk xylem density; wood economics |
| Abstract |
Premise of the study : Wood density correlates with mechanical and physiological strategies of trees and is important for estimating global carbon stocks. Nonetheless, the relationship between branch and trunk xylem density has been poorly explored in neotropical trees. Here, we examine this relationship in trees from French Guiana and its variation among different families and sites, to improve the understanding of wood density in neotropical forests. Methods : Trunk and branch xylem densities were measured for 1909 trees in seven sites across French Guiana. A major-axis fit was performed to explore their general allometric relationship and its variation among different families and sites. Key results : Trunk xylem and branch xylem densities were significantly positively correlated, and their relationship explained 47% of the total variance. Trunk xylem was on average 9% denser than branch xylem. Family-level differences and interactions between family and site accounted for more than 40% of the total variance, whereas differences among sites explained little variation. Conclusions : Variation in xylem density within individual trees can be substantial, and the relationship between branch xylem and trunk xylem densities varies considerably among families and sites. As such, whole-tree biomass estimates based on non-destructive branch sampling should correct for both taxonomic and environmental factors. Furthermore, detailed estimates of the vertical distribution of wood density within individual trees are needed to determine the extent to which relying solely upon measures of trunk wood density may cause carbon stocks in tropical forests to be overestimated. |
| Address |
[Sarmiento, Carolina; Patino, Sandra; Baraloto, Christopher] INRA, UMR Ecol Forets Guyane, Kourou 97310, French Guiana, Email: carolinasar@gmail.com |
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BOTANICAL SOC AMER INC |
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0002-9122 |
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ISI:000285747900019 |
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EcoFoG @ eric.marcon @ |
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290 |
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Verryckt, L.T.; Van Langenhove, L.; Ciais, P.; Courtois, E.A.; Vicca, S.; Peñuelas, J.; Stahl, C.; Coste, S.; Ellsworth, D.S.; Posada, J.M.; Obersteiner, M.; Chave, J.; Janssens, I.A. |
| Title |
Coping with branch excision when measuring leaf net photosynthetic rates in a lowland tropical forest |
Type |
Journal Article |
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2020 |
Publication |
Biotropica |
Abbreviated Journal |
Biotropica |
| Volume |
52 |
Issue |
4 |
Pages |
608-615 |
| Keywords |
branch cutting; canopy physiology; French Guiana; gas exchange; photosynthesis; rainforest; stomatal conductance; ecological modeling; environmental conditions; forest canopy; leaf; measurement method; photosynthesis; tree; tropical forest; Gruidae |
| Abstract |
Measuring leaf gas exchange from canopy leaves is fundamental for our understanding of photosynthesis and for a realistic representation of carbon uptake in vegetation models. Since canopy leaves are often difficult to reach, especially in tropical forests with emergent trees up to 60 m at remote places, canopy access techniques such as canopy cranes or towers have facilitated photosynthetic measurements. These structures are expensive and therefore not very common. As an alternative, branches are often cut to enable leaf gas exchange measurements. The effect of branch excision on leaf gas exchange rates should be minimized and quantified to evaluate possible bias. We compared light-saturated leaf net photosynthetic rates measured on excised and intact branches. We selected branches positioned at three canopy positions, estimated relative to the top of the canopy: upper sunlit foliage, middle canopy foliage, and lower canopy foliage. We studied the variation of the effects of branch excision and transport among branches at these different heights in the canopy. After excision and transport, light-saturated leaf net photosynthetic rates were close to zero for most leaves due to stomatal closure. However, when the branch had acclimated to its new environmental conditions—which took on average 20 min—light-saturated leaf net photosynthetic rates did not significantly differ between the excised and intact branches. We therefore conclude that branch excision does not affect the measurement of light-saturated leaf net photosynthesis, provided that the branch is recut under water and is allowed sufficient time to acclimate to its new environmental conditions. © 2020 The Association for Tropical Biology and Conservation |
| Address |
UMR 5174 Laboratoire Evolution et Diversité Biologique, Université Paul Sabatier, CNRS, Toulouse, France |
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Blackwell Publishing Ltd |
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Edition |
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| ISSN |
00063606 (Issn) |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
no |
| Call Number |
EcoFoG @ webmaster @ |
Serial |
960 |
| Permanent link to this record |
