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| Author |
Bompy, F.; Lequeue, G.; Imbert, D.; Dulormne, M. |
Title  |
Increasing fluctuations of soil salinity affect seedling growth performances and physiology in three Neotropical mangrove species |
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Journal Article |
| Year |
2014 |
Publication |
Plant and Soil |
Abbreviated Journal |
Plant and Soil |
| Volume |
380 |
Issue |
1 |
Pages |
399-413 |
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Acclimation; Avicennia germinans; Hypersalinity; Laguncularia racemosa; Leaf gas exchange; Rhizophora mangle; Salt stress |
| Abstract |
Background: Micro-tidal wetlands are subject to strong seasonal variations of soil salinity that are likely to increase in amplitude according to climate model predictions for the Caribbean. Whereas the effects of constant salinity levels on the physiology of mangrove species have been widely tested, little is known about acclimation to fluctuations in salinity. Aims and methods: The aim of this experiment was to characterize the consequences of the rate of increase in salinity (slow versus fast) and salinity fluctuations over time versus constant salt level. Seedling mortality, growth, and leaf gas exchange of three mangrove species, Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle were investigated in semicontrolled conditions at different salt levels (0, 685, 1025, and 1370 mM NaCl). Results: Slow salinity increase up to 685 mM induced acclimation, improving the salt tolerance of A. germinans and L. racemosa, but had no effect on R. mangle. During fluctuations between 0 and 685 mM, A. germinans and R. mangle were not affected by a salinity drop to zero, whereas L. racemosa took advantage of the brief freshwater episode as shown by the durable improvement of photosynthesis and biomass production. Conclusions: This study provides new insights into physiological resistance and acclimation to salt stress. We show that seasonal variations of salinity may affect mangrove seedlings' morphology and physiology as much as annual mean salinity. Moreover, more severe dry seasons due to climate change may impact tree stature and species composition in mangroves through higher mortality rates and physiological disturbance at the seedling stage. © 2014 Springer International Publishing Switzerland. |
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EA 926 DYNECAR, UFR des Sciences Exactes et Naturelles, Université des Antilles et de la Guyane, BP 592, 97 159 Pointe-à-Pitre cedex, Guadeloupe (F.W.I.), France |
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Cited By :7; Export Date: 7 February 2017 |
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EcoFoG @ webmaster @ |
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726 |
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Houel, E.; Rodrigues, A.M.S.; Jahn-Oyac, A.; Bessière, J.-M.; Eparvier, V.; Deharo, E.; Stien, D. |
| Title |
In vitro antidermatophytic activity of Otacanthus azureus (Linden) Ronse essential oil alone and in combination with azoles |
Type |
Journal Article |
| Year |
2014 |
Publication |
Journal of Applied Microbiology |
Abbreviated Journal |
J. Appl. Microbiol. |
| Volume |
116 |
Issue |
2 |
Pages |
288-294 |
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Antifungal activity; Azoles; Dermatophytes; Essential oil; Otacanthus azureus; Synergy |
| Abstract |
Aims: We determined the chemical composition and investigated the antifungal activity of Otacanthus azureus (Linden) Ronse essential oil (EO) against a range of dermatophytes alone or in combination with azole antifungals. Methods and Results: Aerial parts of the plant were steam-distilled and the obtained oil was analysed by gas chromatography/mass spectrometry and 1H-NMR. It was shown to be largely composed of sesquiterpenes, with the main component being β-copaen-4-α-ol. Using broth microdilution techniques, this oil was found to have remarkable in vitro antifungal activities. Minimum inhibitory concentrations as low as 4 μg ml-1 were recorded. The analysis of the combined effect of the O. azureus EO with azoles using chequerboard assays revealed a synergism between the EO and ketoconazole, fluconazole or itraconazole against Trichophyton mentagrophytes. Notably, the O. azureus essential oil showed low cytotoxicity to VERO cells. Conclusions: The O. azureus essential oil alone or in combination with azoles is a promising antifungal agent in the treatment for human dermatomycoses caused by filamentous fungi. Significance and Impact of the Study: There is much interest in the study of essential oils for the discovery of new antimicrobial drugs. This study has highlighted the antidermatophytic activity of the O. azureus EO. © 2013 The Society for Applied Microbiology. |
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Institut de Recherche pour le Développement (IRD), UMR 152 Pharma-DEV, Toulouse, France |
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Export Date: 9 February 2014; Source: Scopus; Coden: Jamif; Language of Original Document: English; Correspondence Address: Houël, E.; CNRS – UMR Ecologie des Forêts de Guyane (EcoFoG), Institut Pasteur de la Guyane, 23 Avenue Pasteur, BP6010, 97306 Cayenne Cedex, French Guiana; email: emeline.houel@ecofog.gf |
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EcoFoG @ webmaster @ |
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526 |
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Bonhomme, Camille ; Céréghino, Régis ; Carrias, Jean-François ; Compin, Arthur ; Corbara, Bruno ; Jassey, Vincent E.J. ; Leflaive, Joséphine ; Farjalla, Vinicius F. ; Marino, Nicholas A.C. ; Rota, Thibault ; Srivastava, Diane S. ; Leroy, Celine |
| Title |
In situ resistance, not immigration, supports invertebrate community resilience to drought intensification in a neotropical ecosystem |
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Journal Article |
| Year |
2021 |
Publication |
Journal of Animal Ecology |
Abbreviated Journal |
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90 |
Issue |
9 |
Pages |
2015-2026 |
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While future climate scenarios predict declines in precipitations in many regions of the world, little is known of the mechanisms underlying community resilience to prolonged dry seasons, especially in ‘naïve’ Neotropical rainforests. Predictions of community resilience to intensifying drought are complicated by the fact that the underlying mechanisms are mediated by species' tolerance and resistance traits, as well as rescue through dispersal from source patches. We examined the contribution of in situ tolerance-resistance and immigration to community resilience, following drought events that ranged from the ambient norm to IPCC scenarios and extreme events. We used rainshelters above rainwater-filled bromeliads of French Guiana to emulate a gradient of drought intensity (from 1 to 3.6 times the current number of consecutive days without rainfall), and we analysed the post-drought dynamics of the taxonomic and functional community structure of aquatic invertebrates to these treatments when immigration is excluded (by netting bromeliads) or permitted (no nets). Drought intensity negatively affected invertebrate community resistance, but had a positive influence on community recovery during the post-drought phase. After droughts of 1 to 1.4 times the current intensities, the overall invertebrate abundance recovered within invertebrate life cycle durations (up to 2 months). Shifts in taxonomic composition were more important after longer droughts, but overall, community composition showed recovery towards baseline states. The non-random patterns of changes in functional community structure indicated that deterministic processes like environmental filtering of traits drive community re-assembly patterns after a drought event. Community resilience mostly relied on in situ tolerance-resistance traits. A rescue effect of immigration after a drought event was weak and mostly apparent under extreme droughts. Under climate change scenarios of drought intensification in Neotropical regions, community and ecosystem resilience could primarily depend on the persistence of suitable habitats and on the resistance traits of species, while metacommunity dynamics could make a minor contribution to ecosystem recovery. Climate change adaptation should thus aim at identifying and preserving local conditions that foster in situ resistance and the buffering effects of habitat features. |
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British Ecological Society |
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EcoFoG @ webmaster @ |
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1012 |
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Harper, Anna B. ; Williams, Karina E. ; McGuire, Patrick ; Duran Rojas, Maria Carolina ; Hemming, Debbie ; Verhoef, Anne ; Huntingford, Chris ; Rowland, Lucy ; Marthews, Toby ; Breder Eller, Cleiton ; Mathison, Camilla ; Nobrega, Rodolfo L.B. ; Gedney, Nicola ; Vidale, Pier Luigi ; Otu-Larbi, Fred ; Pandey, Divya |
| Title |
Improvement of modeling plant responses to low soil moisture in JULESvn4.9 and evaluation against flux tower measurements |
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Journal Article |
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2021 |
Publication |
Geoscientific Model Development |
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14 |
Issue |
6 |
Pages |
3269-3294 |
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Drought is predicted to increase in the future due to climate change, bringing with it myriad impacts on ecosystems. Plants respond to drier soils by reducing stomatal conductance in order to conserve water and avoid hydraulic damage. Despite the importance of plant drought responses for the global carbon cycle and local and regional climate feedbacks, land surface models are unable to capture observed plant responses to soil moisture stress. We assessed the impact of soil moisture stress on simulated gross primary productivity (GPP) and latent energy flux (LE) in the Joint UK Land Environment Simulator (JULES) vn4.9 on seasonal and annual timescales and evaluated 10 different representations of soil moisture stress in the model. For the default configuration, GPP was more realistic in temperate biome sites than in the tropics or high-latitude (cold-region) sites, while LE was best simulated in temperate and high-latitude (cold) sites. Errors that were not due to soil moisture stress, possibly linked to phenology, contributed to model biases for GPP in tropical savanna and deciduous forest sites. We found that three alternative approaches to calculating soil moisture stress produced more realistic results than the default parameterization for most biomes and climates. All of these involved increasing the number of soil layers from 4 to 14 and the soil depth from 3.0 to 10.8 m. In addition, we found improvements when soil matric potential replaced volumetric water content in the stress equation (the “soil14psi” experiments), when the critical threshold value for inducing soil moisture stress was reduced (“soil14p0”), and when plants were able to access soil moisture in deeper soil layers (“soil14_dr*2”). For LE, the biases were highest in the default configuration in temperate mixed forests, with overestimation occurring during most of the year. At these sites, reducing soil moisture stress (with the new parameterizations mentioned above) increased LE and increased model biases but improved the simulated seasonal cycle and brought the monthly variance closer to the measured variance of LE. Further evaluation of the reason for the high bias in LE at many of the sites would enable improvements in both carbon and energy fluxes with new parameterizations for soil moisture stress. Increasing the soil depth and plant access to deep soil moisture improved many aspects of the simulations, and we recommend these settings in future work using JULES or as a general way to improve land surface carbon and water fluxes in other models. In addition, using soil matric potential presents the opportunity to include plant functional type-specific parameters to further improve modeled fluxes. |
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European Geosciences Union |
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EcoFoG @ webmaster @ |
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1057 |
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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 |
| Year |
2020 |
Publication |
Journal of Geophysical Research: Biogeosciences |
Abbreviated Journal |
J. Geophys. Res. Biogeosci. |
| Volume |
125 |
Issue |
8 |
Pages |
e2020JG005677 |
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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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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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Talaga, S.; Dejean, A.; Azémar, F.; Dumont, Y.; Leroy, C. |
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Impacts of biotic and abiotic parameters on immature populations of Aedes aegypti |
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Journal Article |
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2020 |
Publication |
Journal of Pest Science |
Abbreviated Journal |
J. Pest Sci. |
| Volume |
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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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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2015 |
Publication |
Trees – Structure and Function |
Abbreviated Journal |
Trees – Structure and Function |
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29 |
Issue |
1 |
Pages |
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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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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2008 |
Publication |
Global Change Biology |
Abbreviated Journal |
Glob. Change Biol. |
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14 |
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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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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. |
| Address |
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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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 |
Abbreviated Journal |
Veg. Hist. Archaeobot. |
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18 |
Issue |
6 |
Pages |
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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