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| Author |
Bréchet, L.; Ponton, S.; Alméras, T.; Bonal, D.; Epron, D. |
| Title |
Does spatial distribution of tree size account for spatial variation in soil respiration in a tropical forest? |
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Journal Article |
| Year |
2011 |
Publication |
Plant and Soil |
Abbreviated Journal |
Plant Soil |
| Volume |
347 |
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1 |
Pages |
293-303 |
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Forest structure; Litterfall; Root mass; Soil respiration; Spatial variation; Tropical forest; aboveground production; forest inventory; litterfall; range size; size distribution; soil respiration; spatial distribution; spatial variation; stand dynamics; tropical forest |
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We explored the relationship between soil processes, estimated through soil respiration (Rsoil), and the spatial variation in forest structure, assessed through the distribution of tree size, in order to understand the determinism of spatial variations in Rsoil in a tropical forest. The influence of tree size was examined using an index (Ic) calculated for each tree as a function of (1) the trunk cross section area and (2) the distance from the measurement point. We investigated the relationships between Ic and litterfall, root mass and Rsoil, respectively. Strong significant relationships were found between Ic and both litterfall and root mass. Rsoil showed a large range of variations over the 1-ha experimental plot, from 1. 5 to 12. 6 gC m-2 d-1. The best relationship between Ic and Rsoil only explained 17% of the spatial variation in Rsoil. These results support the assumption that local spatial patterns in litter production and root mass depend on tree distribution in tropical forests. Our study also emphasizes the modest contribution of tree size distribution-which is mainly influenced by the presence of the biggest trees (among the large range size of the inventoried trees greater than 10 cm diameter at 1. 30 m above ground level or at 0. 5 m above the buttresses)-in explaining spatial variations in Rsoil. © 2011 Springer Science+Business Media B.V. |
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Nancy Université, Université Henri Poincaré, UMR 1137, Ecologie et Ecophysiologie Forestières, Faculté des Sciences, 54500 Vandoeuvre les Nancy, France |
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Export Date: 21 October 2011; Source: Scopus; Coden: Plsoa; doi: 10.1007/s11104-011-0848-1; Language of Original Document: English; Correspondence Address: Bréchet, L.; INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou cedex, French Guiana; email: laetitiabrechet@yahoo.fr |
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Lebrini, M.; Mbomekallé, I.M.; Dolbecq, A.; Marrot, J.; Berthet, P.; Ntienoue, J.; Sécheresse, F.; Vigneron, J.; Etcheberry, A. |
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Manganese(III)-containing wells-dawson sandwich-type polyoxometalates: Comparison with their manganese(II) counterparts |
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Journal Article |
| Year |
2011 |
Publication |
Inorganic Chemistry |
Abbreviated Journal |
Inorg. Chem. |
| Volume |
50 |
Issue |
14 |
Pages |
6437-6448 |
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We present the synthesis and structural characterization, assessed by various techniques (FTIR, TGA, UV-vis, elemental analysis, single-crystal X-ray diffraction for three compounds, magnetic susceptibility, and electrochemistry) of five manganese-containing Wells-Dawson sandwich-type (WDST) complexes. The dimanganese(II)-containing complex, [Na2(H2O) 2MnII2(As2W15O 56)2]18- (1), was obtained by reaction of MnCl2 with 1 equiv of [As2W15O 56]12- in acetate medium (pH 4.7). Oxidation of 1 by Na2S2O8 in aqueous solution led to the dimanganese(III) complex [Na2(H2O)2Mn III2(As2W15O56) 2]16- (2), while its trimanganese(II) homologue, [Na(H2O)2MnII(H2O)Mn II2(As2W15O56) 2]17- (3), was obtained by addition of ca. 1 equiv of MnCl2 to a solution of 1 in 1 M NaCl. The trimanganese(III) and tetramanganese(III) counterparts, [MnIII(H2O)Mn III2(As2W15O56) 2]15- (4) and [MnIII2(H 2O)2MnIII2(As2W 15O56)2]12- (6), are, respectively, obtained by oxidation of aqueous solutions of 3 and [MnII2(H2O)2MnII2(As 2W15O56)2]16- (5) by Na2S2O8. Single-crystal X-ray analyses were carried out on 2, 3, and 4. BVS calculations and XPS confirmed that the oxidation state of Mn centers is +II for complexes 1, 3, and 5 and +III for 2, 4, and 6. A complete comparative electrochemical study was carried out on the six compounds cited above, and it was possible to observe the distinct redox steps MnIV/III and MnIII/II. Magnetization measurements, as a function of temperature, confirm the presence of antiferromagnetic interactions between the Mn ions in these compounds in all cases with the exception of compound 2. © 2011 American Chemical Society. |
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Laboratoire de Physico-Chimie de L'Etat Solide, ICMMO, Université Paris-Sud, Bâtiment 410, 91405 Orsay Cedex, France |
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00201669 (Issn) |
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Export Date: 21 October 2011; Source: Scopus; Coden: Inoca; doi: 10.1021/ic102237x; Language of Original Document: English; Correspondence Address: Mbomekallé, I.M.; Institut Lavoisier de Versailles, UMR 8180, CNRS Université de Versailles Saint-Quentin, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France; email: israel.mbomekalle@chimie.uvsq.fr |
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Lebrini, M.; Roos, C.; Vezin, H.; Robert, F. |
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Electrochemical and theoretical studies of adsorption of some indole derivates at C38 Steel/Sulfuric acid interface as corrosion inhibitors |
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Journal Article |
| Year |
2011 |
Publication |
International Journal of Electrochemical Science |
Abbreviated Journal |
Int.J.Electrochem.Sci. |
| Volume |
6 |
Issue |
9 |
Pages |
3844-3857 |
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Acidic media; Adsorption; C38 steel; Corrosion inhibitors; Theoretical calculations |
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The inhibitive action of 9H-pyrido[3,4-b]indole (norharmane) and 1-Methyl-9H-pyrido[3,4-b]indole (harmane) on corrosion of C38 steel in 0.5 M H2SO4 solution was investigated through electrochemical techniques. The experimental results obtained revealed that these compounds inhibited the steel corrosion in acid solution for all concentrations studied. Polarization measurements indicate that the examined compounds act as a mixed inhibitor and its inhibition efficiency increases with inhibitor concentration. Data obtained from ac impedance technique show a frequency distribution and therefore a modelling element with frequency dispersion behaviour, a constant phase element (CPE), has been used. The adsorption of used compounds on the steel surface obeys Langmuir's isotherm. The ΔG°ads values were calculated and discussed for both inhibitors. Significant correlations are obtained between inhibition efficiency and quantum chemical parameters using quantitative structure-activity relationship (QSAR) method. © 2011 by ESG. |
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Laboratoire de Chimie Organique et Macromoléculaire, UMR-CNRS 8009, USTL BâtC4, F-59655 Villeneuve d'Ascq Cedex, France |
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14523981 (Issn) |
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Export Date: 21 October 2011; Source: Scopus; Language of Original Document: English; Correspondence Address: Robert, F.; Laboratoire Matériaux et Molécules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana; email: florent.robert@guyane.univ-ag.fr |
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Faustin, M.; Lebrini, M.; Robert, F.; Roos, C. |
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Corrosion studies of C38 steel by alkaloids extract of a tropical plant type |
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Journal Article |
| Year |
2011 |
Publication |
International Journal of Electrochemical Science |
Abbreviated Journal |
Int.J.Electrochem.Sci. |
| Volume |
6 |
Issue |
9 |
Pages |
4095-4113 |
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Acidic media; C38 steel; Corrosion inhibitor; Plant extract |
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Alkaloids extract of Aspidosperma album was tested as corrosion inhibitor for C38 steel in 1 M HCl by using polarization and electrochemical impedance spectroscopy (EIS). Potentiodynamic polarization curves indicated that the plant extract behaves as mixed-type inhibitors. Impedance measurements showed that the double-layer capacitance decreased and charge-transfer resistance increased with increase in the inhibitors concentration and hence increasing in inhibition efficiency. The effect of temperature on the corrosion behavior of C38 steel in 1 M HCl with and without addition of plant extract was studied in the temperature range 25 – 55°C. The adsorption of the inhibitor molecules was in accordance with the Langmuir adsorption isotherm. The results obtained show that this plant extract could serve as an effective inhibitor for the corrosion of C38 steel in hydrochloric acid. © 2011 by ESG. |
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Laboratoire Matériaux et Molécules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana |
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Export Date: 21 October 2011; Source: Scopus; Language of Original Document: English; Correspondence Address: Roos, C.; Laboratoire Matériaux et Molécules en Milieu Amazonien, UAG-UMR ECOFOG, Campus Trou Biran, Cayenne 97337, French Guiana; email: florent.robert@guyane.univ-ag.fr |
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Staudt, K.; Serafimovich, A.; Siebicke, L.; Pyles, R.D.; Falge, E. |
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Vertical structure of evapotranspiration at a forest site (a case study) |
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Journal Article |
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2011 |
Publication |
Agricultural and Forest Meteorology |
Abbreviated Journal |
Agric. For. Meterol. |
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151 |
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6 |
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709-729 |
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Eddy-covariance; Evapotranspiration; In-canopy profiles; Model; Picea abies L.; Sap flux; coniferous forest; ecosystem modeling; eddy covariance; evapotranspiration; forest canopy; sap flow; Fichtelgebirge; Germany; Picea abies |
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The components of ecosystem evapotranspiration of a Norway spruce forest (Picea abies L.) as well as the vertical structure of canopy evapotranspiration were analyzed with a combination of measurements and models for a case study of 5 days in September 2007. Eddy-covariance and sap flux measurements were performed at several heights within the canopy at the FLUXNET site Waldstein-Weidenbrunnen (DE-Bay) in the Fichtelgebirge mountains in Germany. Within and above canopy fluxes were simulated with two stand-scale models, the 1D multilayer model ACASA that includes a third-order turbulence closure and the 3D model STANDFLUX. The soil and understory evapotranspiration captured with the eddy-covariance system in the trunk space constituted 10% of ecosystem evapotranspiration measured with the eddy-covariance system above the canopy. A comparison of transpiration measured with the sap flux technique and inferred from below and above canopy eddy-covariance systems revealed higher estimates from eddy-covariance measurements than for sap flux measurements. The relative influences of possible sources of this mismatch, such as the assumption of negligible contribution of evaporation from intercepted water, and differences between the eddy-covariance flux footprint and the area used for scaling sap flux measurements, were discussed. Ecosystem evapotranspiration as well as canopy transpiration simulated with the two models captured the dynamics of the measurements well, but slightly underestimated eddy-covariance values. Profile measurements and models also gave us the chance to assess in-canopy profiles of canopy evapotranspiration and the contributions of in-canopy layers. For daytime and a coupled or partly coupled canopy, mean simulated profiles of both models agreed well with eddy-covariance measurements, with a similar performance of the ACASA and the STANDFLUX model. Both models underestimated profiles for nighttime and decoupled conditions. During daytime, the upper half of the canopy contributed approximately 80% to canopy evapotranspiration, whereas during nighttime the contribution shifted to lower parts of the canopy. © 2010 Elsevier B.V. |
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Max Planck Institute for Chemistry, Biogeochemistry Department, Joh.-J.-Becherweg 27, 55128 Mainz, Germany |
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01681923 (Issn) |
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Cited By (since 1996): 3; Export Date: 21 October 2011; Source: Scopus; Coden: Afmee; doi: 10.1016/j.agrformet.2010.10.009; Language of Original Document: English; Correspondence Address: Staudt, K.; University of Bayreuth, Department of Micrometeorology, 95440 Bayreuth, Germany; email: katharina.staudt@uni-bayreuth.de |
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Rodrigues, A.M.; Amusant, N.; Beauchene, J.; Eparvier, V.; Lemenager, N.; Baudasse, C.; Espindola, L.S.; Stien, D. |
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The termiticidal activity of Sextonia rubra (Mez) van der Werff (Lauraceae) extract and its active constituent rubrynolide |
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Journal Article |
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2011 |
Publication |
Pest Management Science |
Abbreviated Journal |
Pest Manage. Sci. |
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67 |
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11 |
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1420-1423 |
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Nasutitermes macrocephalus; Reticulitermes flavipes; Rubrynolide; Sextonia rubra extract; Wood preservation |
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Termites are degradation agents that inflict severe damage on wood. Some long-lasting Amazonian trees can resist these insects by producing toxic secondary metabolites. These metabolites could potentially replace synthetic termiticidal products which are becoming more restricted to use. Results: Sextonia rubra is resistant to termite-induced degradation. It has been demonstrated that this species naturally produces an ethyl-acetate-soluble termiticidal metabolite, rubrynolide, to protect its wood. Assays in the presence of tropical and invasive termites established that both rubrynolide and crude ethyl acetate extract from S. rubra wood can be used as a treatment for the protection of sensitive woods against termites. Conclusion: Rubrynolide and S. rubra extract are promising candidates for the replacement of synthetic termiticides. © 2011 Society of Chemical Industry. |
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CNRS-Institut de Chimie des Substances Naturelles, Gif-sur-Yvette, France |
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1526498x (Issn) |
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Export Date: 26 October 2011; Source: Scopus; Coden: Pmscf; doi: 10.1002/ps.2167; Language of Original Document: English; Correspondence Address: Rodrigues, A.M.; UMR Ecofog, Institut d'Enseignement Supérieur de la Guyane, BP792, 97337 Cayenne Cedex, France; email: alice.rodrigues@pop.com.br |
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362 |
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Odonne, G.; Herbette, G.; Eparvier, V.; Bourdy, G.; Rojas, R.; Sauvain, M.; Stien, D. |
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Antileishmanial sesquiterpene lactones from Pseudelephantopus spicatus, a traditional remedy from the Chayahuita Amerindians (Peru). Part III |
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Journal Article |
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2011 |
Publication |
Journal of Ethnopharmacology |
Abbreviated Journal |
J. Ethnopharmacol. |
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137 |
Issue |
1 |
Pages |
875-879 |
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Asteraceae; Chayahuita; Hirsutinolides; Leishmaniasis; Peru; Pseudelephantopus spicatus; Traditional remedy; 8,13 diacetylpiptocarphol; acetyl 13 o ethylpiptocarphol; amphotericin B; antileishmanial agent; plant extract; Pseudelephantopus spicatus extract; sesquiterpene lactone derivative; unclassified drug; ursolic acid; amastigote; article; biological activity; Ic 50; in vitro study; Leishmania; leishmaniasis; medicinal plant; nonhuman; Peru; Pseudelephantopus spicatus; traditional medicine; Asteraceae; Leishmania amazonensis; Pseudelephantopus spicatus |
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Ethnopharmacological relevance: The study of traditional remedies used by the Chayahuita, an ethnic group from the Peruvian Amazonia, has prompted us to investigate in detail the ethanolic extract of Pseudelephantopus spicatus (Juss. ex Aubl.) C.F. Baker, which has demonstrated strong biological activity towards Leishmania amazonensis. Our goal was to discover the active compound of this plant-based remedy. Materials and methods: A bioguided fractionation of the crude extract was undertaken based on the biological activity recorded against Leishmania amazonensis axenic amastigotes in in vitro bioassays. Results: Three strongly to moderately active compounds were isolated: two hirsutinolides (the 8,13-diacetyl-piptocarphol and the 8-acetyl-13-O-ethyl-piptocarphol) and ursolic acid. IC50 against Leishmania amazonensis axenic amastigotes are respectively 0.2, 0.37 and 0.99 μM (while IC50 of amphotericin B is 0.41 μM). These compounds have never been isolated from this plant species, and germacranolides have never been identified as potential antileishmanial agents. Conclusions: The compounds isolated from Pseudelephantopus spicatus account for the antileishmanial activity of the plant, thus giving support to its use by the Chayahuita in Peru. © 2011 Elsevier Ireland Ltd All rights reserved. |
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Laboratorio de Investigación y Desarrollo, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Avenida Honorio Delgado 430, San Martin de Porres, Lima, Peru |
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Export Date: 21 October 2011; Source: Scopus; Coden: Joetd; doi: 10.1016/j.jep.2011.07.008; Language of Original Document: English; Correspondence Address: Odonne, G.; Bureau du CNRS en Guyane, CNRS – UPS 2561, 2 Avenue Gustave Charlery, 97300 Cayenne, France; email: guillaume.odonne@gmail.com; Chemicals/CAS: amphotericin B, 1397-89-3, 30652-87-0; ursolic acid, 77-52-1 |
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Vincent, G.; Weissenbacher, E.; Sabatier, D.; Blanc, L.; Proisy, C.; Couteron, P. |
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Detection des variations de structure de peuplements en foret dense tropicale humide par lidar aeroporte |
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Journal Article |
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2010 |
Publication |
Revue Francaise de Photogrammetrie et de Teledetection |
Abbreviated Journal |
Rev. Fr. Photogramm. Teledetect. |
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191 |
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42-51 |
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Above-ground biomass estimation; Canopy height model; Stem diameter distribution; Tropical moist forest; Above ground biomass; Above ground level; Airborne LiDAR; Basal area; Canopy Height Models; Carbon stocks; Characterisation; Classical fields; Coefficient of variation; Diameter distributions; Digital terrain model; Flooded areas; Forest ecology; Forest structure; Forest type; High spatial resolution; Individual tree; LIDAR data; Light detection and ranging; Local statistics; Long term; Management issues; Natural forests; Natural variation; Pearson correlation coefficients; Quadratic mean diameter; Soil characteristics; Soil cover; Spatial changes; Spatial resolution; Stem density; Stem diameter; Stem height; Strong correlation; Tree height; Tropical moist forest; Tropical rain forest; Vegetation structure; Vertical accuracy; Water regime; Discriminant analysis; Ecology; Optical radar; Remote sensing; Soils; Statistics; Stem cells; Temperature control; Tropics; Vegetation; Forestry; Biomass; Discriminant Analysis; Ecology; Forest Canopy; Forestry; Radar; Remote Sensing; Stems; Temperature Control; Tropical Atmospheres |
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Characterisation of forest structure is a major stake for forestry, species conservation, carbon stock estimates and many forest ecology and management issues. At large scale natural forest structure tends to vary according to climate and geomorphomology (Paget, 1999; Steege et al., 2006) while soil characteristics (and notably water regime) and syMgenetic stage add some finer scale variation (Oldeman, 1989; Sabatier et al., 1997). Forest structure characterisation traditionally relies on field-based collection of individual tree dimensions such as stem diameter and stem height sampled across tracks of forest (Hall et al., 1998). However, such field intensive methods are costly, and of low accuracy regarding measures of tree heights. Airborne light detection and ranging (LiDAR) technology provides horizontal and vertical Information at high spatial resolutions and vertical accuracies (Lim et al., 2003; Hyyppä et al., 2004). It has the potential for gathering vegetation structure data over large areas rapidly at moderate cost and hence is of particular relevance for poorly sampled, difficult to access and largely unexplored tropical rainforests. In this study we examined the ability of airborne LiDAR to detect spatial changes in the structure of dense tropical rain forest and we probed this remote sensing approach against local statistics derived from stem diameters (i.e. classical field data information) mapped across a large track of forest at a long term experimental site in French Guyana. The large variability in forest structure occurring at the experimental site is du to natural variation of the soil cover (and notably drainage properties) combined with various logging intensities applied 15 years before the LiDAR data were acquired. On this basis ten different forest types were identified at the site (figure 1 and 3). Various stem based statistics were computed for a series of meshes with cells ranging from 30 by 30 m plots to 250 by 250 m plots. These statistics included basal area, stem density, quadratic mean diameter, and diameter distribution percentiles. Similarly local statistics were extracted either from the Canopy Height Model (e.g. median height, mean height, standard height deviation, height coefficient of variation, height percentiles, frequency of hits below 5 m above ground level). Additionally a wetness index (Böhner et al., 2002) was computed at each node of a 5 by 5 m grid from the Digital Terrain Model also extracted from the LiDAR data set. We used both types of cell statistics to discriminate the various forest types. Comparison between the two approaches for a range of spatial resolution is available from in table 1. Results indicate that LiDAR based statistics are essentially as powerful as field based statistics to discriminate forest types at coarse scale. This reflects the very strong correlation between the CHM and the field based stem diameter data. For example (figure 5) the Pearson correlation coefficient between median height and quadratic mean diameter for cells of 125 by 125 m is 0.945 (n=0.72). When a finer resolution is required however as for the detection of seasonally flooded bottomland forest along thalwegs, then LiDAR technology proves more efficient than field based inventories as it combines information from the DTM and the CHM. The wetness index alone correctly retrieves about 2 thirds of the seasonally flooded areas. All in all, discriminant analysis performance of the LiDAR derived information approaches 80% when classifying forests cover at the finest scale of 5 by 5m into 10 different types and reaches 87% when a coarser classification Into 6 forest types is considered (figure 4). |
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IRD, UMR AMAP, Montpellier, France |
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Cited By (since 1996): 1; Export Date: 21 October 2011; Source: Scopus; Language of Original Document: French; Correspondence Address: Vincent, G.; IRD, UMR AMAP, Kourou – BP 701 (CIRAD) 97387 Kourou cedex -Guyane, France |
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Baraloto, C.; Herault, B.; Paine, C.E.T.; Massot, H.; Blanc, L.; Bonal, D.; Molino, J.-F.; Nicolini, E.A.; Sabatier, D. |
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Contrasting taxonomic and functional responses of a tropical tree community to selective logging |
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Journal Article |
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2012 |
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Journal of Applied Ecology |
Abbreviated Journal |
J. Appl. Ecol. |
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49 |
Issue |
4 |
Pages |
861-870 |
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Canopy gap dynamics; Disturbance; French Guiana; Functional diversity; Functional evenness; Functional traits; Light partitioning; Species richness; Tropical rain forest |
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1.Considerable debate surrounds the extent to which tropical forests can be managed for resource extraction while conserving biodiversity and ecosystem properties, which depend on functional composition. Here we evaluate the compatibility of these aims by examining the effects of logging on taxonomic and functional diversity and composition in a tropical forest. 2.Twenty years after selective logging, we inventoried 4140 stems regenerating in logging gaps and adjacent undisturbed areas, and we integrated a database of 13 functional traits describing leaf and wood economics of tropical trees. 3.We found no differences in taxonomic and functional richness among habitats, but logging gaps had significantly higher taxonomic and functional evenness. 4.Logging also effected striking, long-term changes in both species and functional composition. In particular, the xylem density of recruits in logging gaps was 6% less than in unlogged forests, leaves were 11% less tough and had 6-13% greater mineral nutrient concentrations. 5.Synthesis and applications. Our results suggest that managers of tropical forests should limit overall surface area converted to logging gaps by creating fewer, larger gaps during selective logging, to reduce impacts on the taxonomic and functional composition of the regenerating stand. Our results suggest that managers of tropical forests should limit overall surface area converted to logging gaps by creating fewer, larger gaps during selective logging, to reduce impacts on the taxonomic and functional composition of the regenerating stand. © 2012 The Authors. Journal of Applied Ecology © 2012 British Ecological Society. |
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CIRAD-ES, Research Unit 'Biens et Services des Ecosystémes Forestiers tropicaux', Embrapa Amazonia Oriental, Caixa Postal, 48, Belem, Para – CEP 66095-100, Brazil |
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Export Date: 30 July 2012; Source: Scopus; Coden: Japea; doi: 10.1111/j.1365-2664.2012.02164.x; Language of Original Document: English; Correspondence Address: Baraloto, C.; INRA, UMR 'Ecologie des Forêts de Guyane', 97387 Kourou Cedex, French Guiana; email: chris.baraloto@ecofog.gf |
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Christensen-Dalsgaard, K.K.; Ennos, A.R.; Fournier, M. |
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Changes in hydraulic conductivity, mechanical properties, and density reflecting the fall in strain along the lateral roots of two species of tropical trees |
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Journal Article |
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2007 |
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Journal of Experimental Botany |
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J. Exp. Bot. |
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58 |
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15-16 |
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4095-4105 |
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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). |
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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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