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Phillips, O.L.; Aragao, L.E.O.C.; Lewis, S.L.; Fisher, J.B.; Lloyd, J.; Lopez-Gonzalez, G.; Malhi, Y.; Monteagudo, A.; Peacock, J.; Quesada, C.A.; van der Heijden, G.; Almeida, S.; Amaral, I.; Arroyo, L.; Aymard, G.; Baker, T.R.; Banki, O.; Blanc, L.; Bonal, D.; Brando, P.; Chave, J.; de Oliveira, A.C.A.; Cardozo, N.D.; Czimczik, C.I.; Feldpausch, T.R.; Freitas, M.A.; Gloor, E.; Higuchi, N.; Jimenez, E.; Lloyd, G.; Meir, P.; Mendoza, C.; Morel, A.; Neill, D.A.; Nepstad, D.; Patino, S.; Penuela, M.C.; Prieto, A.; Ramirez, F.; Schwarz, M.; Silva, J.; Silveira, M.; Thomas, A.S.; ter Steege, H.; Stropp, J.; Vasquez, R.; Zelazowski, P.; Davila, E.A.; Andelman, S.; Andrade, A.; Chao, K.J.; Erwin, T.; Di Fiore, A.; Honorio, E.; Keeling, H.; Killeen, T.J.; Laurance, W.F.; Cruz, A.P.; Pitman, N.C.A.; Vargas, P.N.; Ramirez-Angulo, H.; Rudas, A.; Salamao, R.; Silva, N.; Terborgh, J.; Torres-Lezama, A. |
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Title  |
Drought Sensitivity of the Amazon Rainforest |
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Journal Article |
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Year |
2009 |
Publication |
Science |
Abbreviated Journal |
Science |
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Volume |
323 |
Issue |
5919 |
Pages |
1344-1347 |
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Amazon forests are a key but poorly understood component of the global carbon cycle. If, as anticipated, they dry this century, they might accelerate climate change through carbon losses and changed surface energy balances. We used records from multiple long-term monitoring plots across Amazonia to assess forest responses to the intense 2005 drought, a possible analog of future events. Affected forest lost biomass, reversing a large long-term carbon sink, with the greatest impacts observed where the dry season was unusually intense. Relative to pre-2005 conditions, forest subjected to a 100-millimeter increase in water deficit lost 5.3 megagrams of aboveground biomass of carbon per hectare. The drought had a total biomass carbon impact of 1.2 to 1.6 petagrams (1.2 x 10(15) to 1.6 x 10(15) grams). Amazon forests therefore appear vulnerable to increasing moisture stress, with the potential for large carbon losses to exert feedback on climate change. |
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[Phillips, Oliver L.; Lewis, Simon L.; Lloyd, Jon; Lopez-Gonzalez, Gabriela; Peacock, Julie; Quesada, Carlos A.; van der Heijden, Geertje; Baker, Tim R.; Feldpausch, Ted R.; Gloor, Emanuel; Patino, Sandra; Schwarz, Michael; Chao, Kuo-Jung; Keeling, Helen] Univ Leeds, Sch Geog, Leeds LS2 9JT, W Yorkshire, England, Email: o.phillips@leeds.ac.uk |
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AMER ASSOC ADVANCEMENT SCIENCE |
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0036-8075 |
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ISI:000263876700042 |
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EcoFoG @ eric.marcon @ |
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120 |
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Svensk, M.; Coste, S.; Gérard, B.; Gril, E.; Julien, F.; Maillard, P.; Stahl, C.; Leroy, C. |
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Title |
Drought effects on resource partition and conservation among leaf ontogenetic stages in epiphytic tank bromeliads |
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Journal Article |
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Year |
2020 |
Publication |
Physiologia Plantarum |
Abbreviated Journal |
Physiol. Plant. |
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Volume |
170 |
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4 |
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488-507 |
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Keywords |
chlorophyll; nitrogen; water; Bromeliaceae; drought; metabolism; photosynthesis; plant leaf; Bromeliaceae; Chlorophyll; Droughts; Nitrogen; Photosynthesis; Plant Leaves; Water |
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Studying the response to drought stress of keystone epiphytes such as tank bromeliads is essential to better understand their resistance capacity to future climate change. The objective was to test whether there is any variation in the carbon, water and nutrient status among different leaf ontogenetic stages in a bromeliad rosette subjected to a gradient of drought stress. We used a semi-controlled experiment consisting in a gradient of water shortage in Aechmea aquilega and Lutheria splendens. For each bromeliad and drought treatment, three leaves were collected based on their position in the rosette and several functional traits related to water and nutrient status, and carbon metabolism were measured. We found that water status traits (relative water content, leaf succulence, osmotic and midday water potentials) and carbon metabolism traits (carbon assimilation, maximum quantum yield of photosystem II, chlorophyll and starch contents) decreased with increasing drought stress, while leaf soluble sugars and carbon, nitrogen and phosphorus contents remained unchanged. The different leaf ontogenetic stages showed only marginal variations when subjected to a gradient of drought. Resources were not reallocated between different leaf ontogenetic stages but we found a reallocation of soluble sugars from leaf starch reserves to the root system. Both species were capable of metabolic and physiological adjustments in response to drought. Overall, this study advances our understanding of the resistance of bromeliads faced with increasing drought stress and paves the way for in-depth reflection on their strategies to cope with water shortage. © 2020 Scandinavian Plant Physiology Society |
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Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse, 31062, France |
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Blackwell Publishing Ltd |
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00319317 (Issn) |
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PDF trop gros voir la documentaliste – merci |
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EcoFoG @ webmaster @ |
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943 |
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N'Guessan, A.E.; N'dja, J.K.; Yao, O.N.; Amani, B.H.K.; Gouli, R.G.Z.; Piponiot, C.; Zo-Bi, I.C.; Herault, B. |
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Title |
Drivers of biomass recovery in a secondary forested landscape of West Africa |
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Journal Article |
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2019 |
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Forest Ecology and Management |
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433 |
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325-331 |
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Biomass; Cultivation; Ecology; Recovery; Secondary recovery; Agricultural land; Bayesian frameworks; Diameter-at-breast heights; Forested landscapes; Neotropical forests; Old-growth forest; Physical environments; Secondary forests; Forestry; Dioscorea alata |
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The rapidly growing human population in West Africa has generated increasing demand for agricultural land and forest products. Consequently 90% of the original rainforest cover has now disappeared and the remainder is heavily fragmented and highly degraded. Although many studies have focused on carbon stocks and fluxes in intact African forests, little information exists on biomass recovery rates in secondary forests. We studied a chronosequence of 96 secondary and old-growth forest fragments (0.2 ha each) where 32.103 trees with Diameter at Breast Height > 2.5 cm have been censused. We modelled the biomass recovery trajectories in a time-explicit Bayesian framework and tested the effect on recovery rates of a large set of covariates related to the physical environment, plot history, and forest connectivity. Recovery rate trajectory is highly non-linear: recovery rates accelerated from 1 to 37 years, when biomass recovery reached 4.23 Mg /ha /yr, and decelerated afterwards. We predict that, on average, 10%, 25% and 50% of the old-growth forest biomass is respectively recovered 17, 30, and 51 years after abandonment. Recovery rates are strongly shaped by both the number of remnant trees (residuals of the former old-growth forest) and the previous crop cultivated before abandonment. The latter induced large differences in the time needed to recover 50% of an old-growth forest biomass: from 38 years for former Yam fields up to 86 years for former rice fields. Our results emphasize (i) the very slow recovery rates of West African forests, as compared to Neotropical forests (ii) the long-lasting impacts of past human activities and management choices on ecosystem biomass recovery in West African degraded forests. |
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Elsevier B.V. |
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03781127 (Issn) |
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EcoFoG @ webmaster @ |
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838 |
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Maurice, L.; López, F.; Becerra, S.; Jamhoury, H.; Le Menach, K.; Dévier, M.-H.; Budzinski, H.; Prunier, J.; Juteau-Martineau, G.; Ochoa-Herrera, V.; Quiroga, D.; Schreck, E. |
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Drinking water quality in areas impacted by oil activities in Ecuador: Associated health risks and social perception of human exposure |
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Journal Article |
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Year |
2019 |
Publication |
Science of the Total Environment |
Abbreviated Journal |
Sci. Total Environ. |
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690 |
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1203-1217 |
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Demineralized waters; Domestic waters; Hydrocarbons; Metal(loid)s; Oil activities; Social risk perception; Benzene refining; Health; Health risks; Hydrocarbons; Petroleum refineries; Petroleum refining; Polycyclic aromatic hydrocarbons; Potable water; Risk assessment; Risk perception; Toluene; Trace elements; Water quality; Water wells; Zinc; Arsenic concentration; Demineralized water; Domestic water; Information sources; Living conditions; Microbiological analysis; Natural backgrounds; Oil activities; Water distribution systems |
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The unregulated oil exploitation in the Northern Ecuadorian Amazon Region (NEAR), mainly from 1964 to the 90's, led to toxic compounds largely released into the environment. A large majority of people living in the Amazon region have no access to drinking water distribution systems and collects water from rain, wells or small streams. The concentrations of major ions, trace elements, PAHs (polycyclic aromatic hydrocarbons) and BTEX (benzene, toluene, ethylbenzene, xylenes) were analyzed in different water sources to evaluate the impacts of oil extraction and refining. Samples were taken from the NEAR and around the main refinery of the country (Esmeraldas Oil Refinery/State Oil Company of Ecuador) and were compared with domestic waters from the Southern region, not affected by petroleum activities. In most of the samples, microbiological analysis revealed a high level of coliforms representing significant health risks. All measured chemical compounds in waters were in line with national and international guidelines, except for manganese, zinc and aluminum. In several deep-water wells, close to oil camps, toluene concentrations were higher than the natural background while PAHs concentrations never exceeded individually 2 ng·L−1. Water ingestion represented 99% of the total exposure pathways for carcinogenic and non-carcinogenic elements (mainly zinc) in adults and children, while 20% to 49% of the Total Cancer Risk was caused by arsenic concentrations. The health index (HI) indicates acceptable chronic effects for domestic use according the US-EPA thresholds. Nevertheless, these limits do not consider the cocktail effects of metallic and organic compounds. Furthermore, they do not include the social determinants of human exposure, such as socio-economic living conditions or vulnerability. Most (72%) of interviewed families knew sanitary risks but a discrepancy was observed between knowledge and action: religious beliefs, cultural patterns, information sources, experience and emotions play an important role front to exposure. © 2019 |
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Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel HillNC 2759, United States |
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Elsevier B.V. |
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00489697 (Issn) |
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EcoFoG @ webmaster @ |
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877 |
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Fanin, N.; Hattenschwiler, S.; Barantal, S.; Schimann, H.; Fromin, N. |
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Title |
Does variability in litter quality determine soil microbial respiration in an Amazonian rainforest? |
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Journal Article |
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Year |
2011 |
Publication |
Soil Biology & Biochemistry |
Abbreviated Journal |
Soil Biol. Biochem. |
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43 |
Issue |
5 |
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1014-1022 |
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Keywords |
Carbon forms; French Guiana; Litter quality; Microbial respiration process; Nitrogen; Phosphorus; Stoichiometry |
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Tree species-rich tropical rainforests are characterized by a highly variable quality of leaf litter input to the soil at small spatial scales. This diverse plant litter is a major source of energy and nutrients for soil microorganisms, particularly in rainforests developed on old and nutrient-impoverished soils. Here we tested the hypothesis that the variability in leaf litter quality produced by a highly diverse tree community determines the spatial variability of the microbial respiration process in the underlying soil. We analyzed a total of 225 litter-soil pairs from an undisturbed Amazonian rainforest in French Guiana using a hierarchical sampling design. The microbial respiration process was assessed using substrate-induced respiration (SIR) and compared to a wide range of quality parameters of the associated litter layer (litter nutrients, carbon forms, stoichiometry, litter mass and pH). The results show that the variability of both litter quality and SIR rates was more important at large than at small scales. SIR rates varied between 1.1 and 4.0 μg h(-1) and were significantly correlated with litter layer quality (up to 50% of the variability explained by the best mixed linear model). Total litter P content was the individual most important factor explaining the observed spatial variation in soil SIR, with higher rates associated to high litter P. SIR rates also correlated positively with total litter N content and with increasing proportions of labile C compounds. However, contrary to our expectation, SIR rates were not related to litter stoichiometry. These data suggest that in the studied Amazonian rainforest, tree canopy composition is an important driver of the microbial respiration process via leaf litter fall, resulting in potentially strong plant-soil feedbacks. (C) 2011 Elsevier Ltd. All rights reserved. |
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[Fanin, Nicolas; Haettenschwiler, Stephan; Barantal, Sandra; Fromin, Nathalie] CNRS, CEFE, UMR 5175, F-34293 Montpellier 5, France, Email: nicolas.fanin@cefe.cnrs.fr |
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Pergamon-Elsevier Science Ltd |
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0038-0717 |
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ISI:000289219500019 |
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EcoFoG @ webmaster @ |
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304 |
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Gloor, M.; Phillips, O.L.; Lloyd, J.J.; Lewis, S.L.; Malhi, Y.; Baker, T.R.; Lopez-Gonzalez, G.; Peacock, J.; Almeida, S.; de Oliveira, A.C.A.; Alvarez, E.; Amaral, I.; Arroyo, L.; Aymard, G.; Banki, O.; Blanc, L.; Bonal, D.; Brando, P.; Chao, K.J.; Chave, J.; Davila, N.; Erwin, T.; Silva, J.; Di Fiore, A.; Feldpausch, T.R.; Freitas, A.; Herrera, R.; Higuchi, N.; Honorio, E.; Jimenez, E.; Killeen, T.; Laurance, W.; Mendoza, C.; Monteagudo, A.; Andrade, A.; Neill, D.; Nepstad, D.; Vargas, P.N.; Penuela, M.C.; Cruz, A.P.; Prieto, A.; Pitman, N.; Quesada, C.; Salomao, R.; Silveira, M.; Schwarz, M.; Stropp, J.; Ramirez, F.; Ramirez, H.; Rudas, A.; ter Steege, H.; Silva, N.; Torres, A.; Terborgh, J.; Vasquez, R.; van der Heijden, G. |
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Does the disturbance hypothesis explain the biomass increase in basin-wide Amazon forest plot data? |
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Journal Article |
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Year |
2009 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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15 |
Issue |
10 |
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2418-2430 |
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Amazon rainforest; carbon sink; disturbance; mortality; power law |
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Positive aboveground biomass trends have been reported from old-growth forests across the Amazon basin and hypothesized to reflect a large-scale response to exterior forcing. The result could, however, be an artefact due to a sampling bias induced by the nature of forest growth dynamics. Here, we characterize statistically the disturbance process in Amazon old-growth forests as recorded in 135 forest plots of the RAINFOR network up to 2006, and other independent research programmes, and explore the consequences of sampling artefacts using a data-based stochastic simulator. Over the observed range of annual aboveground biomass losses, standard statistical tests show that the distribution of biomass losses through mortality follow an exponential or near-identical Weibull probability distribution and not a power law as assumed by others. The simulator was parameterized using both an exponential disturbance probability distribution as well as a mixed exponential-power law distribution to account for potential large-scale blowdown events. In both cases, sampling biases turn out to be too small to explain the gains detected by the extended RAINFOR plot network. This result lends further support to the notion that currently observed biomass gains for intact forests across the Amazon are actually occurring over large scales at the current time, presumably as a response to climate change. |
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[Gloor, M.; Phillips, O. L.; Lloyd, J. J.; Lewis, S. L.; Baker, T. R.; Lopez-Gonzalez, G.; Peacock, J.; Feldpausch, T. R.] Univ Leeds, Sch Geog, Leeds LS2 9JT, W Yorkshire, England, Email: eugloor@googlemail.com |
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WILEY-BLACKWELL PUBLISHING, INC |
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1354-1013 |
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ISI:000269577800006 |
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EcoFoG @ eric.marcon @ |
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196 |
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Bréchet, L.; Ponton, S.; Alméras, T.; Bonal, D.; Epron, D. |
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Does spatial distribution of tree size account for spatial variation in soil respiration in a tropical forest? |
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Journal Article |
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Year |
2011 |
Publication |
Plant and Soil |
Abbreviated Journal |
Plant Soil |
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347 |
Issue |
1 |
Pages |
293-303 |
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Keywords |
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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0032079x (Issn) |
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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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EcoFoG @ webmaster @ |
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345 |
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Coste, S.; Roggy, J.C.; Garraud, L.; Heuret, P.; Nicolini, E.; Dreyer, E. |
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Does ontogeny modulate irradiance-elicited plasticity of leaf traits in saplings of rain-forest tree species? A test with Dicorynia guianensis and Tachigali melinonii (Fabaceae, Caesalpinioideae) |
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Journal Article |
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Year |
2009 |
Publication |
Annals of Forest Science |
Abbreviated Journal |
Ann. For. Sci. |
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66 |
Issue |
7 |
Pages |
701-709 |
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plant architecture; phenotypic plasticity; photosynthetic capacity; leaf structure; tropical rain forest |
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Irradiance elicits a large plasticity in leaf traits, but little is known about the modulation of this plasticity by ontogeny. Interactive effects of relative irradiance and ontogeny were assessed on leaf traits for two tropical rainforest tree species: Dicorynia guianensis Amshoff and Tachigali melinonii (Harms) Barneby (Fabaceae, Caesalpinioideae). Eleven morphological and physiological leaf traits, relative to photosynthetic performance, were measured on saplings at three different architectural development stages (ASD 1, 2 and 3) and used to derive composite traits like photosynthetic N-use efficiency. Measurements were made along a natural irradiance gradient. The effect of ASD was very visible and differed between the two species. For Dicorynia guianensis, only leaf mass-per-area (LMA) significantly increased with ASDs whereas for Tachigali melinonii, almost all traits were affected by ASD: LMA, leaf N content and photosynthetic capacity increased from ASD 1 to ASD 3. Photosynthetic N-use-efficiency was not affected by ASD in any species. Leaf traits were severely modulated by irradiance, whereas the degree of plasticity was very similar among ASDs. Only few interactions were detected between irradiance and ASD, for leaf thickness, carbon content, and the ratio Chl/N in T. melinonii and for photosynthetic capacity in D. guianensis. We conclude that ontogenic development and irradiance-elicited plasticity modulated leaf traits, with almost no interaction, i.e., the degree of irradiance-elicited plasticity was stable across development stages and independent of ontogeny in these two species, at least in the early stages of development assessed here. |
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[Dreyer, Erwin] INRA, UMR Ecol & Ecophysiol Forestieres 1137, F-54280 Champenoux, France, Email: dreyer@nancy.inra.fr |
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EDP SCIENCES S A |
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1286-4560 |
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ISI:000270906600009 |
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EcoFoG @ eric.marcon @ |
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100 |
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Dejean, A.; Petitclerc, F.; Roux, O.; Orivel, J.; Leroy, C. |
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Does exogenic food benefit both partners in an ant-plant mutualism? the case of Cecropia obtusa and its guest Azteca plant-ants |
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2012 |
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Comptes Rendus Biologies |
Abbreviated Journal |
C. R. Biol. |
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335 |
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3 |
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214-219 |
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Keywords |
Ant-plant mutualisms; Azteca; Cecropia obtusa; Myrmecotrophy; Stable isotopes |
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Abstract |
In the mutualisms involving the myrmecophyte Cecropia obtusa and Azteca ovaticeps or A. alfari, both predatory, the ants defend their host trees from enemies and provide them with nutrients (myrmecotrophy). A. ovaticeps provisioned with prey and then 15N-enriched food produced more individuals than did control colonies (not artificially provisioned). This was not true for A. alfari colonies, possibly due to differences in the degree of maturity of the colonies for the chosen range of host tree sizes (less than 3 m in height). Myrmecotrophy was demonstrated for both Azteca species as provisioning the ants with 15N-enriched food translated into higher δ 15N values in host plant tissues, indicating that nitrogen passed from the food to the plant. Thus, the predatory activity of their guest ants benefits the Cecropia trees not only because the ants protect them from defoliators since most prey are phytophagous insects but also because the plant absorbs nutrients. © 2012 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved. |
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IRD, Maladies Infectieuses et Vecteurs, Équipe BEES-IRD, BP 171, Bobo-Dioulasso, Burkina Faso |
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16310691 (Issn) |
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Export Date: 15 April 2012; Source: Scopus; Coden: Crboc; doi: 10.1016/j.crvi.2012.01.002; Language of Original Document: English; Correspondence Address: Dejean, A.; CNRS, Écologie des Forêts de Guyane (UMR-CNRS 8172), Campus Agronomique, 97379 Kourou cedex, France; email: alain.dejean@wanadoo.fr |
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EcoFoG @ webmaster @ |
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391 |
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Author |
Brechet, L.; Ponton, S.; Roy, J.; Freycon, V.; Couteaux, M.M.; Bonal, D.; Epron, D. |
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Title |
Do tree species characteristics influence soil respiration in tropical forests? A test based on 16 tree species planted in monospecific plots |
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Journal Article |
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2009 |
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Plant and Soil |
Abbreviated Journal |
Plant Soil |
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Volume |
319 |
Issue |
1-2 |
Pages |
235-246 |
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Keywords |
Fine root; Litter quality; Nutrient cycling; Plant soil interactions; Soil respiration; Tropical plantations |
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Abstract |
The high spatial variability of soil respiration in tropical rainforests is well evaluated, but influences of biotic factors are not clearly understood. This study underlines the influence of tree species characteristics on soil respiration across a 16-monospecific plot design in a tropical plantation of French Guiana. A large variability of soil CO2 fluxes was observed among plots (i.e. 2.8 to 6.8 μmol m(-2) s(-1)) with the ranking being constant across seasons. There were no significant relationships between soil respiration and soil moisture or soil temperature, neither spatially, nor seasonally. The variability of soil respiration was mainly explained by quantitative factors such as leaf litterfall and basal area. Surprisingly, no significant relationship was observed between soil respiration and root biomass. However, the influence of substrate quality was revealed by a strong relationship between soil respiration and litterfall P (and litterfall N, to a lesser extent). |
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[Ponton, Stephane] Natl Inst Agr Res INRA Ctr Rech Nancy, Forest Ecol & Ecophysiol Unit, UMR EEF, F-54280 Seichamps, France, Email: ponton@nancy.inra.fr |
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0032-079X |
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ISI:000266143400020 |
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110 |
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