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Author Aguilos, M.; Hérault, B.; Burban, B.; Wagner, F.; Bonal, D.
Title What drives long-term variations in carbon flux and balance in a tropical rainforest in French Guiana? Type Journal Article
Year 2018 Publication Agricultural and Forest Meteorology Abbreviated Journal
Volume 253–254 Issue Pages 114-123
Keywords Tropical rainforest; Nee; Gpp; Ecosystem respiration; Radiation; Drought
Abstract A thorough understanding of how tropical forests respond to climate is important to improve ecosystem process models and to reduce uncertainties in current and future global carbon balance calculations. The Amazon rainforest, a major contributor to the global carbon cycle, is subject to strong intra- and interannual variations in climate conditions. Understanding their effect on carbon fluxes between the ecosystem and the atmosphere and on the resulting carbon balance is still incomplete. We examined the long-term (over a 12-year period; 2004–2015) variations in gross primary productivity (GPP), ecosystem respiration (RE) and net ecosystem exchange (NEE) in a tropical rainforest in French Guiana and identified key climatic drivers influencing the changes. The study period was characterized by strong differences in climatic conditions among years, particularly differences in the intensity of the dry and wet seasons, as well as differences in annual carbon fluxes and balance. Annual average GPP varied from 3384.9?g?C?m-2?yr?1 (95% CI [3320.7, 3445.9]) to 4061.2?g?C?m-2?yr?1 (95% CI [3980.1, 4145.0]). RE varied even more than GPP, with a difference of 933.1?C?m-2?yr?1 between the minimum (3020.6?g?C?m-2?yr?1; 95% CI [2889.4, 3051.3]) and maximum (3953.7?g?C?m-2?yr?1; 95% CI [3887.6, 4019.6]) values. Although NEE showed large interannual variability (nine-fold), from ?65.6?g?C?m-2?yr?1 (95% CI [?4.4, ?126.0]) to ?590.5?g?C?m-2 yr?1 (95% CI [?532.3, ?651.6]), the forest remained a carbon sink over the 12-year period. A combination of global radiation (Rg), relative extractable water (REW) and soil temperature (Ts) explained 51% of the daily variations for GPP, 30% for RE and 39% for NEE. Global radiation was always the best predictor of these variations, but soil water content and temperature did also influence carbon fluxes and balance. Seasonally, Rg was the major controlling factor for GPP, RE and NEE during the wet season. During the dry season, variations in carbon fluxes and balance were poorly explained by climate factors. Yet, REW was the key driver of variations in NEE during the dry season. This study highlights that, over the long-term, carbon fluxes and balance in such tropical rainforest ecosystems are largely controlled by both radiation and water limitation. Even though variations in Rg have a greater impact on these fluxes, water limitation during seasonal droughts is enough to reduce ecosystem productivity, respiration and carbon uptake. The reduced precipitation expected in tropical rainforest areas under future climatic conditions will therefore strongly influence carbon fluxes and carbon uptake. This study also highlights the importance for land surface or dynamic global vegetation models to consider the main drivers of carbon fluxes and balance separately for dry and wet seasons.
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ISSN 0168-1923 ISBN Medium
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Call Number (down) EcoFoG @ webmaster @ Serial 792
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Author Guitet, S.; Sabatier, D.; Brunaux, O.; Couteron, P.; Denis, T.; Freycon, V.; Gonzalez, S.; Hérault, B.; Jaouen, G.; Molino, J.-F.; Pélissier, R.; Richard-Hansen, C.; Vincent, G.
Title Disturbance Regimes Drive the Diversity of Regional Floristic Pools Across Guianan Rainforest Landscapes Type Journal Article
Year 2018 Publication Scientific Reports Abbreviated Journal Sci. Rep.
Volume 8 Issue Pages 3872
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Abstract Disturbances control rainforest dynamics, and, according to the intermediate disturbance hypothesis (IDH), disturbance regime is a key driver of local diversity. Variations in disturbance regimes and their consequences on regional diversity at broad spatiotemporal scales are still poorly understood. Using multidisciplinary large-scale inventories and LiDAR acquisitions, we developed a robust indicator of disturbance regimes based on the frequency of a few early successional and widely distributed pioneer species. We demonstrate at the landscape scale that tree-species diversity and disturbance regimes vary with climate and relief. Significant relationships between the disturbance indicator, tree-species diversity and soil phosphorus content agree with the hypothesis that rainforest diversity is controlled both by disturbance regimes and long-term ecosystem stability. These effects explain the broad-scale patterns of floristic diversity observed between landscapes. In fact, species-rich forests in highlands, which have benefited from long-term stability combined with a moderate and regular regime of local disturbances, contrast with less diversified forests on recently shaped lowlands, which have undergone more recent changes and irregular dynamics. These results suggest that taking the current disturbance regime into account and including geomorphological stratifications in climate-vegetation models may be an effective way to improve the prediction of changes in species diversity under climate change. © 2018 The Author(s).
Address AgroParisTech, EcoFoG, Kourou, French Guiana
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Notes Export Date: 21 March 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 798
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Author Morel, H.; Lehnebach, R.; Cigna, J.; Ruelle, J.; Nicolini, É.; Beauchene, J.
Title Basic wood density variations of Parkia velutina Benoist, a long-lived heliophilic Neotropical rainforest tree Type Journal Article
Year 2018 Publication Bois et Forets des Tropiques Abbreviated Journal
Volume 335 Issue Pages 59-69
Keywords Curvilinear pattern; French Guiana; Intra-tree; Tropical species
Abstract Investigations of basic radial wood density (WD) in tropical trees revealed linear patterns and some curvilinear patterns. Studies usually disregard longitudinal variations, which are often considered to be similar to radial variations. This study aimed to show (1) a new radial curvilinear WD pattern, (2) differences in amplitude between radial and longitudinal gradients and (3) to partition WD variations according to different scales in Parkia velutina, an emergent tree found in Neotropical rain forests. We collected full discs from six felled trees and radial cores from 10 standing trees to check WD variability, plus one dominant axis per tree for analysis of height growth rates. This species showed very high growth rates indicative of heliophilic habits. WD varied from 0.194 to 0.642 g/cm3. Such amplitude is rarely observed within the same tree. Radial variation in WD was curvilinear, with an amplitude generally less than the longitudinal amplitude. Consequently, in mature trees, WD values in the crown were higher than those in the outer trunk. WD variations can be highly significant at different scales. The variance partitioning also revealed that the whole WD range of Parkia velutina is more accurately estimated intra-individually when both longitudinal and radial gradient are covered.
Address INRA, LERFoB, AgroParisTech, Nancy, France
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Notes Export Date: 20 April 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 799
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Author Pétillon, J.; Leroy, B.; Djoudi, E.A.; Vedel, V.
Title Small and large spatial scale coexistence of ctenid spiders in a neotropical forest (French Guiana) Type Journal Article
Year 2018 Publication Tropical Zoology Abbreviated Journal
Volume 31 Issue 2 Pages 85-98
Keywords Araneae; flooding; Guianese shield; inselberg; juveniles
Abstract While spiders constitute the most abundant and diverse arthropods in many habitats, they remained under-studied, especially in tropical rainforests. The goal of this study is to assess the spatial distribution of the spider family Ctenidae by assessing associations of species diversity and population traits among different habitat conditions. Fieldwork was carried out during 2013 in habitats varying in flooding frequency (plateau vs. flooded forest) and elevation (inselberg vs. lowland) in the Nouragues National Natural Reserve, French Guiana. Assemblage composition, population structure, and trait measurements of one dominant species were assessed using hand collection in replicated quadrats. We found strong effects on ctenid assemblages attributable to both elevation and flooding, with changes in relative abundance of species among habitats, but few correlated densities between species. At the population level, main differences in species distribution between and within habitats were detected only when juveniles were taken into account. No effect of elevation was found on the measurements of traits of the dominant species, but legs were proportionally shorter in flooded habitats, suggesting reduced active dispersal in these habitats. Our study highlights the value of complementary of measures of diversity and traits at different biological scales in Ctenidae.
Address UMR CNRS 8175 Ecologie des Forêts de Guyane, Université Antilles-Guyane, Kourou Cedex, Guyane Française, France
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Notes Export Date: 23 April 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 800
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Author Lehnebach, R.; Beyer, R.; Letort, V.; Heuret, P.
Title The pipe model theory half a century on: a review Type Journal Article
Year 2018 Publication Annals of Botany Abbreviated Journal
Volume 121 Issue 5 Pages 773-795
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Abstract BackgroundMore than a half century ago, Shinozaki et al. (Shinozaki K, Yoda K, Hozumi K, Kira T. 1964a. A quantitative analysis of plant form – the pipe model theory. I. Basic analyses. Japanese Journal of Ecology B: 97–105) proposed an elegant conceptual framework, the pipe model theory (PMT), to interpret the observed linear relationship between the amount of stem tissue and corresponding supported leaves. The PMT brought a satisfactory answer to two vividly debated problems that were unresolved at the moment of its publication: (1) What determines tree form and which rules drive biomass allocation to the foliar versus stem compartments in plants? (2) How can foliar area or mass in an individual plant, in a stand or at even larger scales be estimated? Since its initial formulation, the PMT has been reinterpreted and used in applications, and has undoubtedly become an important milestone in the mathematical interpretation of plant form and functioning.ScopeThis article aims to review the PMT by going back to its initial formulation, stating its explicit and implicit properties and discussing them in the light of current biological knowledge and experimental evidence in order to identify the validity and range of applicability of the theory. We also discuss the use of the theory in tree biomechanics and hydraulics as well as in functional–structural plant modelling.ConclusionsScrutinizing the PMT in the light of modern biological knowledge revealed that most of its properties are not valid as a general rule. The hydraulic framework derived from the PMT has attracted much more attention than its mechanical counterpart and implies that only the conductive portion of a stem cross-section should be proportional to the supported foliage amount rather than the whole of it. The facts that this conductive portion is experimentally difficult to measure and varies with environmental conditions and tree ontogeny might cause the commonly reported non-linear relationships between foliage and stem metrics. Nevertheless, the PMT can still be considered as a portfolio of properties providing a unified framework to integrate and analyse functional–structural relationships.
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ISSN 0305-7364 ISBN Medium
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Notes 10.1093/aob/mcx194 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 801
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Author Ogeron, C.; Odonne, G.; Cristinoi, A.; Engel, J.; Grenand, P.; Beauchene, J.; Clair, B.; Davy, D.
Title Palikur traditional roundwood construction in eastern French Guiana: Ethnobotanical and cultural perspectives Type Journal Article
Year 2018 Publication Journal of Ethnobiology and Ethnomedicine Abbreviated Journal Journal of Ethnobiology and Ethnomedicine
Volume 14 Issue 28 Pages
Keywords Amazonia; Annonaceae; Architecture; Non-timber forest products; Oyapock; Palikur; Sapotaceae; Traditional technological knowledge
Abstract Background: Palikur Amerindians live in the eastern part of French Guiana which is undergoing deep-seated changes due to the geographical and economic opening of the region. So far, Palikur's traditional ecological knowledge is poorly documented, apart from medicinal plants. The aim of this study was to document ethnobotanical practices related to traditional construction in the region. Methods: A combination of qualitative and quantitative methods was used. Thirty-nine Palikur men were interviewed in three localities (Saint-Georges de l'Oyapock, Regina and Trois-Palétuviers) between December 2013 and July 2014. Twenty-four inventories of wood species used in traditional buildings were conducted in the villages, as well as ethnobotanical walks in the neighboring forests, to complete data about usable species and to determine Linnaean names. Results: After an ethnographic description of roundwood Palikur habitat, the in situ wood selection process of Palikur is precisely described. A total of 960 roundwood pieces were inventoried in situ according to Palikur taxonomy, of which 860 were beams and rafters, and 100 posts in 20 permanent and 4 temporary buildings. Twenty-seven folk species were identified. Sixty-three folk species used in construction were recorded during ethnobotanical walks. They correspond to 263 botanical species belonging to 25 families. Posts in permanent buildings were made of yawu (Minquartia guianensis) (51%) and wakap (Vouacapoua americana) (14%). Beams and rafters were made of wood from Annonaceae (79%) and Lecythidaceae (13%) families. The most frequently used species were kuukumwi priye (Oxandra asbeckii), kuukumwi seyne (Pseudoxandra cuspidata), and pukuu (Xylopia nitida and X. cayennensis). Conclusions: Although the Palikur's relationship with their habitat is undergoing significant changes, knowledge about construction wood is still very much alive in the Oyapock basin. Many people continue to construct traditional buildings alongside modern houses, using a wide array of species described here for the first time, along with the techniques used.
Address Université des Antilles, Université de Guyane, CIRAD, UMR Ecologie des Forêts de Guyane (EcoFoG), AgroParisTech, Cirad, INRA, Kourou, France
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Notes Export Date: 7 May 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 802
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Author Petit, M.; Denis, T.; Rux, O.; Richard-Hansen, C.; Berzins, R.
Title Estimating jaguar (Panthera onca) density in a preserved coastal area of French Guiana Type Journal Article
Year 2018 Publication Mammalia Abbreviated Journal Mammalia
Volume 82 Issue 2 Pages 188-192
Keywords camera trapping; density; French Guiana; home range; Panthera onca; spatially explicit capture recapture
Abstract Knowledge of the jaguar population is needed in French Guiana that faces an increase of human-jaguar conflicts. We carried out a camera trap survey to assess jaguar local density and home range size in a preserved coastal area of French Guiana. We ran spatially explicit capture recapture (SECR) models. In our model, the scale parameter σ, that is linked to the home range size, was larger for males (σ=3.87±0.59 SE km) than for females (σ=2.33±0.30 SE km). The assessed jaguar density was 3.22±0.87 SE ind. 100 km â '2, which should be considered as an optimal density in a French Guiana coastal area.
Address Office National de la Chasse et de la Faune Sauvage, Campus Agronomique, BP316, Kourou Cedex, French Guiana
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Notes Export Date: 7 May 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 803
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Author Soong, J.L.; Marañon-Jimenez, S.; Cotrufo, M.F.; Boeckx, P.; Bodé, S.; Guenet, B.; Peñuelas, J.; Richter, A.; Stahl, C.; Verbruggen, E.; Janssens, I.A.
Title Soil microbial CNP and respiration responses to organic matter and nutrient additions: Evidence from a tropical soil incubation Type Journal Article
Year 2018 Publication Soil Biology and Biochemistry Abbreviated Journal
Volume 122 Issue Pages 141-149
Keywords 13c; Cnp; Microbial stoichiometry; Priming; Soil respiration; Tropics
Abstract Soil nutrient availability has a strong influence on the fate of soil carbon (C) during microbial decomposition, contributing to Earth's C balance. While nutrient availability itself can impact microbial physiology and C partitioning between biomass and respiration during soil organic matter decomposition, the availability of labile C inputs may mediate the response of microorganisms to nutrient additions. As soil organic matter is decomposed, microorganisms retain or release C, nitrogen (N) or phosphorus (P) to maintain a stoichiometric balance. Although the concept of a microbial stoichiometric homeostasis has previously been proposed, microbial biomass CNP ratios are not static, and this may have very relevant implications for microbial physiological activities. Here, we tested the hypothesis that N, P and potassium (K) nutrient additions impact C cycling in a tropical soil due to microbial stoichiometric constraints to growth and respiration, and that the availability of energy-rich labile organic matter in the soil (i.e. leaf litter) mediates the response to nutrient addition. We incubated tropical soil from French Guiana with a 13C labeled leaf litter addition and with mineral nutrient additions of +K, +N, +NK, +PK and +NPK for 30 days. We found that litter additions led to a ten-fold increase in microbial respiration and a doubling of microbial biomass C, along with greater microbial N and P content. We found some evidence that P additions increased soil CO2 fluxes. Additionally, we found microbial biomass CP and NP ratios varied more widely than CN in response to nutrient and organic matter additions, with important implications for the role of microorganisms in C cycling. The addition of litter did not prime soil organic matter decomposition, except in combination with +NK fertilization, indicating possible P-mining of soil organic matter in this P-poor tropical soil. Together, these results point toward an ultimate labile organic substrate limitation of soil microorganisms in this tropical soil, but also indicate a complex interaction between C, N, P and K availability. This highlights the difference between microbial C cycling responses to N, P, or K additions in the tropics and explains why coupled C, N and P cycle modeling efforts cannot rely on strict microbial stoichiometric homeostasis as an underlying assumption.
Address INRA, UMR Ecology of Guiana Forests (Ecofog), AgroParisTech, Cirad, CNRS, Université de Guyane, Université des Antilles, Kourou, France
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Notes Export Date: 16 May 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 804
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Author Clair, B.; Déjardin, A.; Pilate, G.; Alméras, T.
Title Is the G-layer a tertiary cell wall? Type Journal Article
Year 2018 Publication Frontiers in Plant Science Abbreviated Journal
Volume 9 Issue Pages 623
Keywords Flax; G-layer; Gelatinous layer; Maturation stress; Secondary cell wall; Tension wood; Tertiary cell wall
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Address LMGC, CNRS, Université de Montpellier, Montpellier, France
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Notes Export Date: 31 May 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 805
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Author 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
Volume 229 Issue 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.
Address Laboratoire des Sciences du Bois, UMR EcoFoG, ZI Pariacabo, Kourou, French Guiana
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Notes Cited By :1; Export Date: 4 June 2018 Approved no
Call Number (down) EcoFoG @ webmaster @ Serial 806
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