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Bremaud, I.; Cabrolier, P.; Gril, J.; Clair, B.; Gerard, J.; Minato, K.; Thibaut, B. |
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Title  |
Identification of anisotropic vibrational properties of Padauk wood with interlocked grain (vol 44, pg 335, 2010) |
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Journal Article |
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2010 |
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Wood Science and Technology |
Abbreviated Journal |
Wood Sci. Technol. |
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44 |
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4 |
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705-705 |
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[Bremaud, Iris; Minato, Kazuya] Kyoto Prefectural Univ, Grad Sch Life & Environm Sci, Lab Forest Resource Circulating Circles, Kyoto 6068522, Japan, Email: iris_bremaud@hotmail.com |
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0043-7719 |
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ISI:000283087900013 |
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EcoFoG @ eric.marcon @ |
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24 |
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Aubry-Kientz, M.; Rossi, V.; Wagner, F.; Herault, B. |
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Title |
Identifying climatic drivers of tropical forest dynamics |
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Journal Article |
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2015 |
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Biogeosciences |
Abbreviated Journal |
Biogeosciences |
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12 |
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19 |
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5583-5596 |
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In the context of climate change, identifying and then predicting the impacts of climatic drivers on tropical forest dynamics is becoming a matter of urgency. To look at these climate impacts, we used a coupled model of tropical tree growth and mortality, calibrated with forest dynamic data from the 20-year study site of Paracou, French Guiana, in order to introduce and test a set of climatic variables. Three major climatic drivers were identified through the variable selection procedure: drought, water saturation and temperature. Drought decreased annual growth and mortality rates, high precipitation increased mortality rates and high temperature decreased growth. Interactions between key functional traits, stature and climatic variables were investigated, showing best resistance to drought for trees with high wood density and for trees with small current diameters. Our results highlighted strong long-term impacts of climate variables on tropical forest dynamics, suggesting potential deep impacts of climate changes during the next century. © Author(s) 2015. |
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Remote Sensing Division, National Institute for Space Research-INPE, São José dos Campos, SP, Brazil |
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Export Date: 16 October 2015 |
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EcoFoG @ webmaster @ |
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631 |
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Clair, B.; Arinero, R.; Leveque, G.; Ramonda, M.; Thibaut, B. |
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Imaging the mechanical properties of wood cell wall layers by atomic force modulation microscopy |
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Journal Article |
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2003 |
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IAWA Journal |
Abbreviated Journal |
IAWA J. |
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24 |
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3 |
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223-230 |
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wood; cell wall; mechanical properties; elastic modulus; tension wood |
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Atomic Force Microscopy in force modulation mode was used to study the elastic properties of the different fibre wall layers of the tension wood of holm oak and normal wood of boco. The method is based on the measurement of the resonance frequency of the microscope lever in contact with the sample. This frequency is related to the reduced Young modulus E* = E/(1-nu(2)) of the material, supposed to be isotropic. 'Elastic' images of the cell are obtained simultaneously with the topographic images, which allows the observation of the mechanical properties of the cells at a nanometric scale. Layers G, S-1, S-2 and ML can clearly be distinguished. By comparison with known materials an estimation of the absolute modulus is given in the range 5-20 GPa, but should be considered with caution, because the inherent anisotropy of the materials has not been taken into account. |
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Univ Montpellier 2, CNRS, UMR 5508, Lab Mecan & Genie Civil, F-34095 Montpellier, France |
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INT ASSOC WOOD ANATOMISTS |
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0928-1541 |
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ISI:000185049700003 |
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EcoFoG @ eric.marcon @ |
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270 |
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Van Langenhove, Leandro ; Depaepe, Thomas ; Verryckt, Lore T. ; Vallicrosa, Helena ; Fuchslueger, Lucia ; Lugli, Laynara F. ; Bréchet, Laëtitia M. ; Ogaya, Roma ; Llusia, Joan ; Urbina, Ifigenia ; Gargallo-Garriga, Albert ; Grau, Oriol ; Richter, Andreas ; Penuelas, Josep ; Van Der Straeten, Dominique ; August Janssens, Ivan A. |
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Title |
Impact of Nutrient Additions on Free-Living Nitrogen Fixation in Litter and Soil of Two French-Guianese Lowland Tropical Forests |
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Journal Article |
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2021 |
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JGR Biogeosciences |
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126 |
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7 |
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e2020JG006023 |
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In tropical forests, free-living Biological nitrogen (N) fixation (BNF) in soil and litter tends to decrease when substrate N concentrations increase, whereas increasing phosphorus (P) and molybdenum (Mo) soil and litter concentrations have been shown to stimulate free-living BNF rates. Yet, very few studies explored the effects of adding N, P, and Mo together in a single large-scale fertilization experiment, which would teach us which of these elements constrain or limit BNF activities. At two distinct forest sites in French Guiana, we performed a 3-year in situ nutrient addition study to explore the effects of N, P, and Mo additions on leaf litter and soil BNF. Additionally, we conducted a short-term laboratory study with the same nutrient addition treatments (+N, +N+P, +P, +Mo, and +P+Mo). We found that N additions alone suppressed litter free-living BNF in the field, but not in the short-term laboratory study, while litter free-living BNF remained unchanged in response to N+P additions. Additionally, we found that P and P+Mo additions stimulated BNF in leaf litter, both in the field and in the lab, while Mo alone yielded no changes. Soil BNF increased with P and P+Mo additions in only one of the field sites, while in the other site soil BNF increased with Mo and P+Mo additions. We concluded that increased substrate N concentrations suppress BNF. Moreover, both P and Mo have the potential to limit free-living BNF in these tropical forests, but the balance between P versus Mo limitation is determined by site-specific characteristics of nutrient supply and demand. |
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American Geophysical Union |
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EcoFoG @ webmaster @ |
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1040 |
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Cohen, M.C.L.; Behling, H.; Lara, R.J.; Smith, C.B.; Matos, H.R.S.; Vedel, V. |
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Impact of sea-level and climatic changes on the Amazon coastal wetlands during the late Holocene |
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Journal Article |
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2009 |
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Vegetation History and Archaeobotany |
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Veg. Hist. Archaeobot. |
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18 |
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6 |
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425-439 |
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Mangrove; Marajo Island; Pollen analysis; Sea-level |
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Wetland dynamics in northern Brazil during the Holocene were studied by pollen analysis and AMS radiocarbon dating of three cores. Near the Amazon mouth region, covered mainly by primary Amazon coastal forest and herbaceous vegetation, the pollen record indicates the dominance of mangroves between 4800 and 1100 cal yr B.P. A contraction of the mangrove area and an expansion of herbaceous and fern vegetation occurred between 1100 and 750 cal yr B.P. The period between 750 and 200 cal yr B.P. is characterized by an expansion of mangrove and a decrease in herbaceous and fern vegetation. This trend continued until the present. On Atalaia Island, the sediment core indicates a period with poor pollen preservation between 830 and 630 cal yr B.P. Between 630 and 330 cal yr B.P., mangroves expanded. Later, up to 45 cal yr B.P., the mangrove area decreased and the herbaceous vegetation expanded. During the last hundred years, the relative sea-level rise most probably favored the mangrove expansion as far as the topographically highest sector on this island, while the herbaceous vegetation decreased. The pollen data from Agua Preta Lake indicate dry conditions, as reflected by the poor pollen preservation between 390 and 240 cal yr B.P. Between 240 and 60 cal yr B.P., restinga and Amazon coastal forest with palms dominated this region. For the last 120 years, the record indicates an expansion of the mangrove area. However, recent confinement of mangrove development to the topographically highest area, and the loss of mangrove areas on the lowest surfaces have led to a net loss of mangrove coverage during the last decades. |
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[Lisboa Cohen, Marcelo Cancela; Smith, Clarisse Beltrao; Soares Matos, Hellen Rosy] Fed Univ Para, Postgrad Program Geol & Geochem, Lab Coastal Dynam, BR-66077530 Belem, PA, Brazil, Email: mcohen@ufpa.br |
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0939-6314 |
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ISI:000271191800001 |
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EcoFoG @ eric.marcon @ |
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193 |
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Degen, B.; Blanc, L.; Caron, H.; Maggia, L.; Kremer, A.; Gourlet-Fleury, S. |
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Impact of selective logging on genetic composition and demographic structure of four tropical tree species |
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Journal Article |
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2006 |
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Biological Conservation |
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Biol. Conserv. |
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131 |
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3 |
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386-401 |
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demography; genetic diversity; logging; phenology; pollen and seed dispersal; simulation; trees; tropics |
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Over-exploitation and fragmentation are serious problems for tropical forests. Most sustainable forest management practices avoid clear-cuts and apply selective logging systems focused on a few commercial species. We applied a simulation model to estimate the impact of such selective logging scenarios on the genetic diversity and demography of four tropical tree species from French Guiana. The simulations used data on genetic and demographic composition, growth, phenology and pollen and seed dispersal obtained for Dicorynia guianensis, Sextonia rubra, Symphonia globulifera and Vouacapoua americana at the experimental site in Paracou. Whereas Symphonia globulifera serves as a model for a species with low logging pressure, the other three species represent the most exploited tree species in French Guiana. In simulations with moderate logging, typical for French Guiana, with large cutting diameter (> 60 cm diameter) and long cutting cycles (65 years), the two species V. americana and Sextonia rubra were not able to recover their initial stock at the end of the rotation period, with a large decrease in the number of individuals and in basal area. Under a more intensive logging system (cutting diameter > 45 cm diameter, cutting cycles of 30 years) that is common practice in the Brazilian Amazon, only Symphonia globulifera showed no negative impact. Generally, the differences between the genetic parameters in the control scenarios without logging and the logging scenarios were surprisingly small. The main reasons for this were the overlapping of generations and the effective dispersal ability of gene vectors in all species, which guarantee relative homogeneity of the genetic structure in different age classes. Nevertheless, decreasing the population size by logging reduced the number of genotypes and caused higher genetic distances between the original population and the population at the end of the logging cycles. Sensitivity analysis showed that genetic changes in the logging scenarios were principally determined by the growth, densities and cutting diameter of each species, and only to a very small extent by the reproductive system including factors such as pollen and seed dispersal and flowering phenology. (c) 2006 Elsevier Ltd. All rights reserved. |
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BFH, Inst Forstgenet & Forstpflanzenzuchtung, D-22927 Grosshansdorf, Germany, Email: b.degen@holz.uni-hamburg.de |
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ELSEVIER SCI LTD |
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0006-3207 |
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ISI:000239139400004 |
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EcoFoG @ eric.marcon @ |
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180 |
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Bonal, D.; Bosc, A.; Ponton, S.; Goret, J.Y.; Burban, B.; Gross, P.; Bonnefond, J.M.; Elbers, J.; Longdoz, B.; Epron, D.; Guehl, J.M.; Granier, A. |
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Impact of severe dry season on net ecosystem exchange in the Neotropical rainforest of French Guiana |
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Journal Article |
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Year |
2008 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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14 |
Issue |
8 |
Pages |
1917-1933 |
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dry season; ecosystem respiration; eddy covariance; gross ecosystem productivity; Neotropical rainforest; net ecosystem productivity; soil drought; solar radiation |
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The lack of information on the ways seasonal drought modifies the CO2 exchange between Neotropical rainforest ecosystems and the atmosphere and the resulting carbon balance hinders our ability to precisely predict how these ecosystems will respond as global environmental changes force them to face increasingly contrasting conditions in the future. To address this issue, seasonal variations in daily net ecosystem productivity (NEPd) and two main components of this productivity, daily total ecosystem respiration (R-Ed) and daily gross ecosystem productivity (GEP(d)), were estimated over 2 years at a flux tower site in French Guiana, South America (5 degrees 16'54'N, 52 degrees 54'44'W). We compared seasonal variations between wet and dry periods and between dry periods of contrasting levels of intensity (i.e. mild vs. severe) during equivalent 93-day periods. During the wet periods, the ecosystem was almost in balance with the atmosphere (storage of 9.0 g C m(-2)). Seasonal dry periods, regardless of their severity, are associated with higher incident radiation and lower R-Ed combined with reduced soil respiration associated with low soil water availability. During the mild dry period, as is normally the case in this region, the amount of carbon stored in the ecosystem was 32.7 g C m(-2). Severe drought conditions resulted in even lower R-Ed, whereas the photosynthetic activity was only moderately reduced and no change in canopy structure was observed. Thus, the severe dry period was characterized by greater carbon storage (64.6 g C m(-2)), emphasizing that environmental conditions, such as during a severe drought, modify the CO2 exchange between Neotropical rainforest ecosystems and the atmosphere and potentially the resulting carbon balance. |
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[Bonal, Damien; Goret, Jean-Yves; Burban, Benoit] INRA, UMR Ecol Forets Guyane, Kourou 97387, French Guiana, Email: damien.bonal@kourou.cirad.fr |
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BLACKWELL PUBLISHING |
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1354-1013 |
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ISI:000257712400015 |
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EcoFoG @ eric.marcon @ |
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133 |
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Bompy, F.; Imbert, D.; Dulormne, M. |
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Impact patterns of soil salinity variations on the survival rate, growth performances, and physiology of Pterocarpus officinalis seedlings |
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Journal Article |
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Year |
2015 |
Publication |
Trees – Structure and Function |
Abbreviated Journal |
Trees – Structure and Function |
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29 |
Issue |
1 |
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119-128 |
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Acclimation; Leaf chemical composition; Leaf gas exchange; NaCl salinity; Tropical swamp forest; Vegetative growth |
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Key message: Pterocarpus officinalisis able to (1) improve its acclimation capacity if soil salinity increases slowly and (2) benefit from afreshwater episode.
Abstract: One likely effect of global change is an increase of the amplitude of salt variations in the soil of brackish coastal wetland forests. In the Antilles, such forests are dominated by the species Pterocarpus officinalis. The study aimed to determine the effect of 3 salinity levels (freshwater, moderate, and hypersalinity—i.e., 0, 10, and 30 ‰, respectively) and 3 patterns of salinity variation (fast or slow salinity increase, fluctuating salinity) on the growth and ecophysiology of P. officinalis seedlings. P. officinalis proved tolerant to 10 ‰ salinity, even if at this salt concentration the water constraint altered the plant’s water status and reduced stomatal conductance. No impact of the pattern of salinity variation was observed at 10 ‰. Seedlings were strongly affected by hypersalinity, but were able to acclimatize efficiently and to improve their performances (higher survival, total biomass, and photosynthesis) when salinity increased slowly. Young P. officinalis were also able to take advantage of a freshwater episode on the longer term, certainly through leaf desalination associated with enhanced photosynthesis and water use efficiency. Higher soil salinity and more intense dry seasons in the context of climate change could affect the stand-level regeneration potential of P. officinalis seedlings. © 2014, Springer-Verlag Berlin Heidelberg. |
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UMR ECOFOG-DYNECAR, UFR des Sciences Exactes et Naturelles, Université des Antilles et de la Guyane, Pointe-à-PitreGuadeloupe (F.W.I.), France |
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Export Date: 9 April 2015 |
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EcoFoG @ webmaster @ |
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595 |
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Talaga, S.; Dejean, A.; Azémar, F.; Dumont, Y.; Leroy, C. |
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Title |
Impacts of biotic and abiotic parameters on immature populations of Aedes aegypti |
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Journal Article |
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Year |
2020 |
Publication |
Journal of Pest Science |
Abbreviated Journal |
J. Pest Sci. |
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93 |
Issue |
3 |
Pages |
941-952 |
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Biocontrol agents; Competition; Ecosystem services; Mosquito control; Mosquito management; Predation; abiotic factor; biotic factor; competitive displacement; disease vector; maturation; mosquito; pest control; Aedes aegypti; Hexapoda; Zika virus |
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In recent centuries, the mosquito Aedes aegypti has spread into most urban areas throughout the tropics. This species is considered the main vector of the chikungunya, dengue, yellow fever and Zika viruses and causes major public health issues. The aim of this study is to investigate the relative influence of biotic and abiotic parameters on immature populations of Ae. aegypti. During a one-year-long field experiment, we monitored 108 macroinvertebrate aquatic communities inhabiting four types of water containers across three different urbanized sites in a Neotropical city. A multimodel inference approach revealed that, in addition to abiotic parameters, biotic interactions with aquatic organisms had an important influence on the abundance of Ae. aegypti and that the urbanized site considered influences the outcomes of the interactions. Controphic species other than mosquitoes aided Ae. aegypti development, suggesting a mechanism of facilitation through a chain of processes. However, the abundance of Ae. aegypti was lowered by competition with native mosquito species in the slightly urbanized area and by predation in more urbanized areas. Competitive displacement and reduction, as well as predation by native aquatic organisms, can be considered a form of ecosystem service. The conservation and/or augmentation of natural enemies should improve the short- and long-term success of incompatible and/or sterile insect techniques, thus opening up perspectives for the future of mosquito management. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature. |
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University of Pretoria, Department of Mathematics and Applied Mathematics, Pretoria, South Africa |
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Springer |
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16124758 (Issn) |
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EcoFoG @ webmaster @ |
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962 |
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Longo, M.; Saatchi, S.; Keller, M.; Bowman, K.; Ferraz, A.; Moorcroft, P.R.; Morton, D.C.; Bonal, D.; Brando, P.; Burban, B.; Derroire, G.; dos-Santos, M.N.; Meyer, V.; Saleska, S.; Trumbore, S.; Vincent, G. |
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Impacts of Degradation on Water, Energy, and Carbon Cycling of the Amazon Tropical Forests |
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Journal Article |
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Year |
2020 |
Publication |
Journal of Geophysical Research: Biogeosciences |
Abbreviated Journal |
J. Geophys. Res. Biogeosci. |
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Volume |
125 |
Issue |
8 |
Pages |
e2020JG005677 |
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Keywords |
Amazon; drought; ecosystem modeling; evapotranspiration; forest degradation; remote sensing; carbon cycle; deforestation; dry season; evapotranspiration; hydrological cycle; logging (timber); net primary production; remote sensing; sensible heat flux; tropical forest; understory; water stress; Amazon River |
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Abstract |
Selective logging, fragmentation, and understory fires directly degrade forest structure and composition. However, studies addressing the effects of forest degradation on carbon, water, and energy cycles are scarce. Here, we integrate field observations and high-resolution remote sensing from airborne lidar to provide realistic initial conditions to the Ecosystem Demography Model (ED-2.2) and investigate how disturbances from forest degradation affect gross primary production (GPP), evapotranspiration (ET), and sensible heat flux (H). We used forest structural information retrieved from airborne lidar samples (13,500 ha) and calibrated with 817 inventory plots (0.25 ha) across precipitation and degradation gradients in the eastern Amazon as initial conditions to ED-2.2 model. Our results show that the magnitude and seasonality of fluxes were modulated by changes in forest structure caused by degradation. During the dry season and under typical conditions, severely degraded forests (biomass loss ≥66%) experienced water stress with declines in ET (up to 34%) and GPP (up to 35%) and increases of H (up to 43%) and daily mean ground temperatures (up to 6.5°C) relative to intact forests. In contrast, the relative impact of forest degradation on energy, water, and carbon cycles markedly diminishes under extreme, multiyear droughts, as a consequence of severe stress experienced by intact forests. Our results highlight that the water and energy cycles in the Amazon are driven by not only climate and deforestation but also the past disturbance and changes of forest structure from degradation, suggesting a much broader influence of human land use activities on the tropical ecosystems. ©2020. The Authors. |
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AMAP, Univ Montpellier, IRD, CIRAD, CNRS, INRAE, Montpellier, France |
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Blackwell Publishing Ltd |
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21698953 (Issn) |
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EcoFoG @ webmaster @ |
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957 |
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