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Author Levionnois, S.; Ziegler, C.; Jansen, S.; Calvet, E.; Coste, S.; Stahl, C.; Salmon, C.; Delzon, S.; Guichard, C.; Heuret, P. doi  openurl
  Title Vulnerability and hydraulic segmentations at the stem–leaf transition: coordination across Neotropical trees Type Journal Article
  Year 2020 Publication New Phytologist Abbreviated Journal New Phytol.  
  Volume 228 Issue 2 Pages 512-524  
  Keywords (up) drought-induced embolism resistance; hydraulic segmentation; leaf-specific conductivity; stem–leaf transition; tropical trees; vulnerability segmentation; air bubble; hydraulic conductivity; leaf; Neotropical Region; rainforest; tropical forest; vulnerability; xylem  
  Abstract Hydraulic segmentation at the stem–leaf transition predicts higher hydraulic resistance in leaves than in stems. Vulnerability segmentation, however, predicts lower embolism resistance in leaves. Both mechanisms should theoretically favour runaway embolism in leaves to preserve expensive organs such as stems, and should be tested for any potential coordination. We investigated the theoretical leaf-specific conductivity based on an anatomical approach to quantify the degree of hydraulic segmentation across 21 tropical rainforest tree species. Xylem resistance to embolism in stems (flow-centrifugation technique) and leaves (optical visualization method) was quantified to assess vulnerability segmentation. We found a pervasive hydraulic segmentation across species, but with a strong variability in the degree of segmentation. Despite a clear continuum in the degree of vulnerability segmentation, eight species showed a positive vulnerability segmentation (leaves less resistant to embolism than stems), whereas the remaining species studied exhibited a negative or no vulnerability segmentation. The degree of vulnerability segmentation was positively related to the degree of hydraulic segmentation, such that segmented species promote both mechanisms to hydraulically decouple leaf xylem from stem xylem. To what extent hydraulic and vulnerability segmentation determine drought resistance requires further integration of the leaf–stem transition at the whole-plant level, including both xylem and outer xylem tissue. © 2020 The Authors. New Phytologist © 2020 New Phytologist Trust  
  Address Univ. Bordeaux, INRAE, BIOGECO, Pessac, F-33615, France  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0028646x (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 952  
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Author Aguilos, M.; Stahl, C.; Burban, B.; Hérault, B.; Courtois, E.; Coste, S.; Wagner, F.; Ziegler, C.; Takagi, K.; Bonal, D. pdf  url
doi  openurl
  Title Interannual and seasonal variations in ecosystem transpiration and water use efficiency in a tropical rainforest Type Journal Article
  Year 2018 Publication Forests Abbreviated Journal Forests  
  Volume 10 Issue 1 Pages  
  Keywords (up) Drought; Evapotranspiration; Radiation; Tropical rainforest; Water use efficiency; Atmospheric radiation; Carbon dioxide; Climate change; Drought; Efficiency; Evapotranspiration; Forestry; Heat radiation; Radiation effects; Soil moisture; Tropics; Water supply; Climate condition; Drought conditions; Interannual variability; Mechanistic models; Seasonal variation; Tropical ecosystems; Tropical rain forest; Water use efficiency; Ecosystems  
  Abstract Warmer and drier climates over Amazonia have been predicted for the next century with expected changes in regional water and carbon cycles. We examined the impact of interannual and seasonal variations in climate conditions on ecosystem-level evapotranspiration (ET) and water use efficiency (WUE) to determine key climatic drivers and anticipate the response of these ecosystems to climate change. We used daily climate and eddyflux data recorded at the Guyaflux site in French Guiana from 2004 to 2014. ET and WUE exhibited weak interannual variability. The main climatic driver of ET and WUE was global radiation (Rg), but relative extractable water (REW) and soil temperature (Ts) did also contribute. At the seasonal scale, ET and WUE showed a modal pattern driven by Rg, with maximum values for ET in July and August and for WUE at the beginning of the year. By removing radiation effects during water depleted periods, we showed that soil water stress strongly reduced ET. In contrast, drought conditions enhanced radiation-normalized WUE in almost all the years, suggesting that the lack of soil water had a more severe effect on ecosystem evapotranspiration than on photosynthesis. Our results are of major concern for tropical ecosystem modeling because they suggest that under future climate conditions, tropical forest ecosystems will be able to simultaneously adjust CO2 and H2O fluxes. Yet, for tropical forests under future conditions, the direction of change in WUE at the ecosystem scale is hard to predict, since the impact of radiation on WUE is counterbalanced by adjustments to soil water limitations. Developing mechanistic models that fully integrate the processes associated with CO2 and H2O flux control should help researchers understand and simulate future functional adjustments in these ecosystems.  
  Address Hokkaido University, Sapporo, 060-0808, Japan  
  Corporate Author Thesis  
  Publisher Mdpi Ag Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 19994907 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Export Date: 1 February 2019; Correspondence Address: Bonal, D.; Université de Lorraine, AgroParisTech, INRA, UMR SilvaFrance; email: damien.bonal@inra.fr; References: Von Randow, C., Zeri, M., Restrepo-Coupe, N., Muza, M.N., de Gonçalves, L.G.G., Costa, M.H., Araujo, A.C., Saleska, S.R., Interannual variability of carbon and water fluxes in Amazonian forest, Cerrado and pasture sites, as simulated by terrestrial biosphere models (2013) Agric. For. Meteorol, 182-183, pp. 145-155; Duffy, P.B., Brando, P., Asner, G.P., Field, C.B., Projections of future meteorological drought and wet periods in the Amazon (2015) Proc. Natl. Acad. Sci. USA, 112, pp. 13172-13177; Cox, P.M., Betts, R.A., Collins, M., Harris, P.P., Huntingford, C., Jones, C.D., Amazonian forest dieback under climate-carbon cycle projections for the 21st century (2004) Theor. Appl. Climatol, 78, pp. 137-156; Poulter, B., Hattermann, F., Hawkins, E., Zaehle, S., Sitch, S., Restrepo-Coupe, N., Heyder, U., Cramer, W., Robust dynamics of Amazon dieback to climate change with perturbed ecosystem model parameters (2010) Glob. Chang. Biol, 16, pp. 2476-2495; Saleska, S.R., Didan, K., Huete, A.R., Da Rocha, H.R., Amazon forests green-up during 2005 drought (2007) Science, 318, p. 612; Phillips, O.L., Aragão, L.E.O.C., Lewis, S.L., Fisher, J.B., Lloyd, J., López-González, G., Malhi, Y., Quesada, C.A., Drought sensitivity of the amazon rainforest (2009) Science, 323, pp. 1344-1347; Bonal, D., Burban, B., Stahl, C., Wagner, F., Hérault, B., The response of tropical rainforests to drought-Lessons from recent research and future prospects (2016) Ann. For. Sci, 73, pp. 27-44; Wang, K.C., Dickinson, R.E., A review of global terrestrial evapotranspiration: Observation, modeling, climatology, and climatic variability (2012) Rev. Geophys, p. 50; Fisher, R.A., Williams, M., da Costa, A.L., Malhi, Y., da Costa, R.F., Almeida, S., Meir, P., The response of an Eastern Amazonian rain forest to drought stress: Results and modelling analyses from a throughfall exclusion experiment (2007) Glob. Chang. Biol, 13, pp. 2361-2378; Costa, M.H., Biajoli, M.C., Sanches, L., Malhado, A.C.M., Hutyra, L.R., Da Rocha, H.R., Aguiar, R.G., De Araújo, A.C., Atmospheric versus vegetation controls of Amazonian tropical rain forest evapotranspiration: Are the wet and seasonally dry rain forests any different? (2010) J. Geophys. Res. Biogeosci, 115, pp. 1-9; Carswell, F.E., Costa, A.L., Palheta, M., Malhi, Y., Meir, P., Costa, J.D.P.R., Ruivo, M.D.L., Clement, R.J., Seasonality in CO2 and H2O flux at an eastern Amazonian rain forest (2002) J. Geophys. Res. D Atmos, 107, p. 8076; Hasler, N., Avissar, R., What controls evapotranspiration in the Amazon basin? (2007) J. Hydrometeorol, 8, pp. 380-395; Da Rocha, H.R., Manzi, A.O., Cabral, O.M., Miller, S.D., Goulden, M.L., Saleska, S.R., Coupe, N.R., Artaxo, R., Patterns of water and heat flux across a biome gradient from tropical forest to savanna in brazil (2009) J. Geophys. Res. Biogeosci, p. 114; Kim, Y., Knox, R.G., Longo, M., Medvigy, D., Hutyra, L.R., Pyle, E.H., Wofsy, S.C., Moorcroft, P.R., Seasonal carbon dynamics and water fluxes in an Amazon rainforest (2012) Glob. Chang. Biol, 18, pp. 1322-1334; Maeda, E.E., Ma, X., Wagner, F.H., Kim, H., Oki, T., Eamus, D., Huete, A., Evapotranspiration seasonality across the Amazon Basin (2017) Earth Syst. Dyn, 8, pp. 439-454; Farquhar, G.D., Ehleringer, J.R., Hubick, K.T., Carbon isotope discrimination and photosynthesis (1989) Ann. Rev. Plant Physiol, 40, pp. 503-537; Hutyra, L.R., Munger, J.W., Saleska, S.R., Gottlieb, E., Daube, B.C., Dunn, A.L., Amaral, D.F., Wofsy, S.C., Seasonal controls on the exchange of carbon and water in an Amazonian rain forest (2007) J. Geophys. Res. Biogeosci; Negrón Juárez, R.I., Hodnett, M.G., Fu, R., Gouden, M.L., von Randow, C., Control of dry season evapotranspiration over the Amazonian forest as inferred from observation at a Southern Amazon forest site (2007) J. Clim, 20, pp. 2827-2839; Fisher, J.B., Malhi, Y., Bonal, D., Da Rocha, H.R., De Araújo, A.C., Gamo, M., Goulden, M.L., Kondo, H., The land-atmosphere water flux in the tropics (2009) Glob. Chang. Biol; Christoffersen, B.O., Restrepo-Coupe, N., Arain, M.A., Baker, I.T., Cestaro, B.P., Ciais, P., Fisher, J.B., Gulden, L., Mechanisms of water supply and vegetation demand govern the seasonality and magnitude of evapotranspiration in Amazonia and Cerrado (2014) Agric. For. Meteorol, 191, pp. 33-50; Da Costa, A.C.L., Rowland, L., Oliveira, R.S., Oliveira, A.A.R., Binks, O.J., Salmon, Y., Vasconcelos, S.S., Poyatos, R., Stand dynamics modulate water cycling and mortality risk in droughted tropical forest (2018) Glob. Chang. Biol; Huang, M., Piao, S., Sun, Y., Ciais, P., Cheng, L., Mao, J., Poulter, B., Wang, Y., Change in terrestrial ecosystem water-use efficiency over the last three decades (2015) Glob. Chang. Biol; Brienen, R.J.W., Wanek, W., Hietz, P., Stable carbon isotopes in tree rings indicate improved water use efficiency and drought responses of a tropical dry forest tree species (2011) Trees, 25, pp. 103-113; Yu, G., Song, X., Wang, Q., Liu, Y., Guan, D., Yan, J., Sun, X., Wen, X., Water-use efficiency of forest ecosystems in eastern China and its relations to climatic variables (2008) New Phytol, 177, pp. 927-937; Aguilos, M., Hérault, B., Burban, B., Wagner, F., Bonal, D., What drives long-term variations in carbon flux and balance in a tropical rainforest in French Guiana? Agric (2018) For. Meteorol, pp. 253-254; Bonal, D., Bosc, A., Ponton, S., Goret, J.Y., Burban, B.T., Gross, P., Bonnefond, J.M., Epron, D., Impact of severe dry season on net ecosystem exchange in the Neotropical rainforest of French Guiana (2008) Glob. Chang. Biol; Aubinet, M., Grelle, A., Ibrom, A., Rannik, U., Moncrieff, J.B., Foken, T., Kowalski, A.S., Bernhofer, C., Estimates of the annual net carbon and water exchange of forests: The Euroflux methodology (2000) Adv. Ecol. Res, 30, pp. 113-175; Wagner, F., Hérault, B., Stahl, C., Bonal, D., Rossi, V., Modeling water availability for trees in tropical forests (2011) Agric. For. Meteorol, 151, pp. 1202-1213; Kuglitsch, F.G., Reichstein, M., Beer, C., Carrara, A., Ceulemans, R., Granier, A., Janssens, I.A., Loustau, D., Characterisation of ecosystem water-use efficiency of european forests from eddy covariance measurements (2008) Biogeosci. Discuss, 5, pp. 4481-4519; Dekker, S.C., Groenendijk, M., Booth, B.B.B., Huntingford, C., Cox, P.M., Spatial and temporal variations in plant water-use efficiency inferred from tree-ring, eddy covariance and atmospheric observations (2016) Earth Syst. Dyn, 7, pp. 525-533; Yang, Y., Guan, H., Batelaan, O., McVicar, T.R., Long, D., Piao, S., Liang, W., Simmons, C.T., Contrasting responses of water use efficiency to drought across global terrestrial ecosystems (2016) Sci. Rep, 6, p. 23284; Granier, A., Bréda, N., Biron, P., Villette, S., A lumped water balance model to evaluate duration and intensity of drought constraints in forest stands (1999) Ecol. Model, 116, pp. 269-283; Kume, T., Takizawa, H., Yoshifuji, N., Tanaka, K., Tantasirin, C., Tanaka, N., Suzuki, M., Impact of soil drought on sap flow and water status of evergreen trees in a tropical monsoon forest in northern Thailand (2007) For. Ecol. Manag, 238, pp. 220-230; Xiao, J., Sun, G., Chen, J., Chen, H., Chen, S., Dong, G., Gao, S., Han, S., Carbon fluxes, evapotranspiration, and water use efficiency of terrestrial ecosystems in China (2013) Agric. For. Meteorol; Boese, S., Jung, M., Carvalhais, N., Reichstein, M., The importance of radiation for semi-empirical water-use efficiency models (2017) Biogeosciences, 14, pp. 3015-3026; Bonal, D., Ponton, S., Le Thiec, D., Richard, B., Ningre, N., Hérault, B., Ogée, J., Sabatier, D., Leaf functional response to increasing atmospheric CO2 concentrations over the last century in two northern Amazonian tree species: An historical δ13C and δ18O approach using herbarium samples (2011) Plant Cell Environ, 34, pp. 1332-1344; Wagner, F., Rossi, V., Stahl, C., Bonal, D., Hérault, B., Water availability is the main climate driver of neotropical tree growth (2012) PLoS ONE, 7; Van der Molen, M.K., Dolman, A.J., Ciais, P., Eglin, T., Gobron, N., Law, B.E., Meir, P., Reichstein, M., Drought and ecosystem carbon cycling (2011) Agric. For. Meteorol, 151, pp. 765-773; Allen, C.D., Macalady, A.K., Chenchouni, H., Bachelet, D., McDowell, N., Vennetier, M., Kitzberger, T., Hogg, E.H., A global overview of drought and heat-induced tree mortality reveals emerging climate change risks for forests (2010) For. Ecol. Manag, 259, pp. 660-684; Da Rocha, H.R., Goulden, M.L., Miller, S.D., Menton, M.C., Pinto, L.D., De Freitas, H.C., Seasonality of water and heat fluxes over a tropical forest in eastern Amazonia (2004) Ecol. Appl, 14, pp. 22-32; Baldocchi, D., Falge, E., Gu, L., Olson, R., Hollinger, D., Running, S., Anthoni, P., Evans, R., FLUXNET: A New tool to study the temporal and spatial variability of ecosystem-scale carbon dioxide, water vapor, and energy flux densities (2001) Bull. Am. Meteorol. Soc, 82, pp. 2415-2434; Stahl, C., Hérault, B., Rossi, V., Burban, B., Bréchet, C., Bonal, D., Depth of soil water uptake by tropical rainforest trees during dry periods: Does tree dimension matter? (2013) Oecologia, 173, pp. 1191-1201; Nepstad, D.C., De Carvalho, C.R., Davidson, E.A., Jipp, P.H., Lefebvre, P.A., Negreiros, G.H., Da Silva, E.D., Vieira, S., The role of deep roots in the hydrological and carbon cycles of Amazonian forests and pastures (1994) Nature; Lee, J.-E., Boyce, K., Impact of the hydraulic capacity of plants on water and carbon fluxes in tropical South America (2010) J. Geophys. Res; Xiao, X., Zhang, Q., Saleska, S., Hutyra, L., De Camargo, P., Wofsy, S., Frolking, S., Moore, B., Satellite-based modeling of gross primary production in a seasonally moist tropical evergreen forest (2005) Remote Sens. Environ, 94, pp. 105-122; Wagner, F.H., Hérault, B., Bonal, D., Stahl, C., Anderson, L.O., Baker, T.R., Becker, G.S., Botosso, P.C., Climate seasonality limits leaf carbon assimilation and wood productivity in tropical forests (2016) Biogeosciences, 13, pp. 2537-2562; Stahl, C., Burban, B., Wagner, F., Goret, J.-Y., Bompy, F., Bonal, D., Influence of Seasonal Variations in Soil Water Availability on Gas Exchange of Tropical Canopy Trees (2013) Biotropica, 45, pp. 155-164; Maréchaux, I., Bonal, D., Bartlett, M.K., Burban, B., Coste, S., Courtois, E.A., Dulormne, M., Mirabel, A., Dry-season decline in tree sapflux is correlated with leaf turgor loss point in a tropical rainforest (2018) Funct. Ecol, 32, pp. 2285-2297; Chaves, M.M., Maroco, J.P., Pereira, J.S., Understanding plant responses to drought-from genes to the whole plant (2003) Funct. Plant Biol, 30, pp. 239-264 Approved no  
  Call Number EcoFoG @ webmaster @ Serial 856  
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Author Coste, S.; Roggy, J.C.; Imbert, P.; Born, C.; Bonal, D.; Dreyer, E. openurl 
  Title Leaf photosynthetic traits of 14 tropical rain forest species in relation to leaf nitrogen concentration and shade tolerance Type Journal Article
  Year 2005 Publication Tree Physiology Abbreviated Journal Tree Physiol.  
  Volume 25 Issue 9 Pages 1127-1137  
  Keywords (up) functional diversity; leaf carbon; leaf nitrogen; nitrogen-use efficiency; photosynthetic capacity; tropical rain forest  
  Abstract Variability of leaf traits related to photosynthesis was assessed in seedlings from 14 tree species growing in the tropical rain forest of French Guiana. Leaf photosynthetic capacity (maximum rate of carboxylation and maximum rate of electron transport) was estimated by fitting a biochemical model of photosynthesis to response curves of net CO2 assimilation rate versus intercellular CO2 mole fraction. Leaf morphology described by leaf mass per unit leaf area (LMA), density and thickness, as well as area- and mass-based nitrogen (N) and carbon (C) concentrations, were recorded on the same leaves. Large interspecific variability was detected in photosynthetic capacity as well as in leaf structure and leaf N and C concentrations. No correlation was found between leaf thickness and density. The correlations between area- and mass-based leaf N concentration and photosynthetic capacity were poor. Conversely, the species differed greatly in relative N allocation to carboxylation and bioenergetics. Principal component analysis (PCA) revealed that, of the recorded traits, only the computed fraction of total leaf N invested in photosynthesis was tightly correlated to photosynthetic capacity. We also used PCA to test to what extent species with similar shade tolerances displayed converging leaf traits related to photosynthesis. No clear-cut ranking could be detected among the shade-tolerant groups, as confirmed by a one-way ANOVA. We conclude that the large interspecific diversity in photosynthetic capacity was mostly explained by differences in the relative allocation of N to photosynthesis and not by leaf N concentration, and that leaf traits related to photosynthetic capacity did not discriminate shade-tolerance ranking of these tropical tree species.  
  Address CNRS Ecol Forets Guyane, INRA, ENGREF,CIRAD, Unite Mixte Rech, Kourou 97387, French Guiana, Email: roggy.j@cirad.fr  
  Corporate Author Thesis  
  Publisher HERON PUBLISHING Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0829-318X ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000231555200005 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 230  
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Author Coste, S.; Roggy, J.C.; Sonnier, G.; Dreyer, E. openurl 
  Title Similar irradiance-elicited plasticity of leaf traits in saplings of 12 tropical rainforest tree species with highly different leaf mass to area ratio Type Journal Article
  Year 2010 Publication Functional Plant Biology Abbreviated Journal Funct. Plant Biol.  
  Volume 37 Issue 4 Pages 342-355  
  Keywords (up) functional diversity; light availability; photosynthetic nitrogen use efficiency; photosynthetic capacity; tropical rainforest  
  Abstract Leaf traits of tropical tree species display an important inter-specific diversity, as detected for instance in the large range of values of leaf mass : area ratio (LMA). They also demonstrate a large irradiance-elicited plasticity, but there is still debate whether this plasticity differs among species. To address this question, leaf traits were recorded on saplings from 12 rainforest tree species in French Guiana, grown under approximately 5, 10 and 20% relative irradiance. Fifteen structural and physiological leaf traits related to photosynthesis were measured. The irradiance-elicited plasticity was quantified using a relative distance plasticity index. A large inter-specific diversity was detected for all leaf traits. A principal component analysis opposed species with a large mass-based photosynthesis, respiration, N content and photosynthetic nitrogen use efficiency, to species with a large leaf mass : area ratio, LMA. The two pioneer species used in this study displayed the largest photosynthetic capacity (and lowest LMA) and ranked at one end of the species continuum. Relative irradiance affected almost all traits with the exception of mass-based photosynthesis. A weak interaction was found between species and relative irradiance and the species ranking was maintained among relative irradiance treatments for the majority of the traits. A principal component analysis of the values of relative-distance plasticity index failed to reveal any consistent patterns of traits or species. We concluded that irradiance-elicited plasticity of leaf traits was similar among species irrespective of LMA and successional status, despite the occurrence of a large inter-specific diversity for the investigated traits.  
  Address [Dreyer, Erwin] Nancy Univ, INRA, UMR Ecol & Ecophysiol Forestieres 1137, IFR Ecosyst Forestiers Agroressources Biomol & Al, F-54280 Champenoux, France, Email: dreyer@nancy.inra.fr  
  Corporate Author Thesis  
  Publisher CSIRO PUBLISHING Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 1445-4408 ISBN Medium  
  Area Expedition Conference  
  Notes ISI:000275979100009 Approved no  
  Call Number EcoFoG @ eric.marcon @ Serial 63  
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Author Levionnois, Sébastien ; Ziegler, Camille ; Heuret, Patrick ; Jansen, Steven ; Stahl, Clément ; Calvet, Emma ; Goret, Jean-Yves ; Bonal, Damien ; Coste, Sabrina doi  openurl
  Title Is vulnerability segmentation at the leaf‑stem transition a drought resistance mechanism? A theoretical test with a trait‑based model for Neotropical canopy tree species Type Journal Article
  Year 2021 Publication Annals of Forest Science Abbreviated Journal  
  Volume 78 Issue 4 Pages 78-87  
  Keywords (up) Neotropics, bark, canopy, capacitance, drought, drought tolerance, embolism, leaves, models, transpiration, trees, tropical rain forests, xylem  
  Abstract Leaf-stem vulnerability segmentation predicts lower xylem embolism resistance in leaves than stem. However, although it has been intensively investigated these past decades, the extent to which vulnerability segmentation promotes drought resistance is not well understood. Based on a trait-based model, this study theoretically supports that vulnerability segmentation enhances shoot desiccation time across 18 Neotropical tree species. CONTEXT: Leaf-stem vulnerability segmentation predicts lower xylem embolism resistance in leaves than stems thereby preserving expensive organs such as branches or the trunk. Although vulnerability segmentation has been intensively investigated these past decades to test its consistency across species, the extent to which vulnerability segmentation promotes drought resistance is not well understood. AIMS: We investigated the theoretical impact of the degree of vulnerability segmentation on shoot desiccation time estimated with a simple trait-based model. METHODS: We combined data from 18 tropical rainforest canopy tree species on embolism resistance of stem xylem (flow-centrifugation technique) and leaves (optical visualisation method). Measured water loss under minimum leaf and bark conductance, leaf and stem capacitance, and leaf-to-bark area ratio allowed us to calculate a theoretical shoot desiccation time (tcᵣᵢₜ). RESULTS: Large degrees of vulnerability segmentation strongly enhanced the theoretical shoot desiccation time, suggesting vulnerability segmentation to be an efficient drought resistance mechanism for half of the studied species. The difference between leaf and bark area, rather than the minimum leaf and bark conductance, determined the drastic reduction of total transpiration by segmentation during severe drought. CONCLUSION: Our study strongly suggests that vulnerability segmentation is an important drought resistance mechanism that should be better taken into account when investigating plant drought resistance and modelling vegetation. We discuss future directions for improving model assumptions with empirical measures, such as changes in total shoot transpiration after leaf xylem embolism.  
  Address  
  Corporate Author Thesis  
  Publisher Springer Link Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 1034  
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