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Dejean, A.; Grangier, J.; Leroy, C.; Orivel, J. |
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Title |
Host plant protection by arboreal ants: looking for a pattern in locally induced responses |
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Journal Article |
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Year |
2008 |
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Evolutionary Ecology Research |
Abbreviated Journal |
Evol. Ecol. Res. |
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10 |
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8 |
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1217-1223 |
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aggressiveness; ant-plant relationships; Azteca; biotic defence; induced responses |
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Background: Among arboreal ants, both territorially dominant species and plant-ants (e.g. species associated with myrmecophytes or plants housing them in hollow structures) protect their host trees against defoliators. Yet, locally induced responses, or the recruitment of nest-mates when a worker discovers it wound on its host-tree, were only noted in plant-ants. We wondered whether this might be due to the examination of the phenomenon being restricted to only six plant-ant species belonging to four genera. Based on the ant genus Azteca, a Neotropical group of arboreal species, we compared five species. The territorially dominant, carton-nester A. chartifex, three plant-ant species [A. alfari and A. ovaticeps associated with myrmecophitic Cecropia (Cecropiaceae), and A. bequaerti associated with Tococa guianensis (Melastomataceae)], and A. schimperi thought to be a temporary social parasite of true Cecropia ants. Methods: We artificially inflicted wounds to the foliage of the host tree of the different ant species. We then compared the number of workers on wounded versus control leaves. Results: We noted a locally induced response in the three plant-ant species as well as in the territorially dominant species, but very slightly so in A. schimperi. |
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[Grangier, Julien; Orivel, Jerome] Univ Toulouse 2, Lab Evolut & Diversite Biol, CNRS, UMR 5174, Toulouse, France, Email: alain.dejean@wanadoo.fr |
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EVOLUTIONARY ECOLOGY LTD |
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1522-0613 |
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ISI:000264041000008 |
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EcoFoG @ eric.marcon @ |
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119 |
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Molto, Q.; Herault, B.; Boreux, J.-J.; Daullet, M.; Rousteau, A.; Rossi, V. |
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Title |
Predicting tree heights for biomass estimates in tropical forests -A test from French Guiana |
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Journal Article |
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Year |
2014 |
Publication |
Biogeosciences |
Abbreviated Journal |
Biogeosciences |
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Volume |
11 |
Issue |
12 |
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3121-3130 |
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The recent development of REDD+ mechanisms requires reliable estimation of carbon stocks, especially in tropical forests that are particularly threatened by global changes. Even though tree height is a crucial variable for computing aboveground forest biomass (AGB), it is rarely measured in large-scale forest censuses because it requires extra effort. Therefore, tree height has to be predicted with height models. The height and diameter of all trees over 10 cm in diameter were measured in 33 half-hectare plots and 9 one-hectare plots throughout northern French Guiana, an area with substantial climate and environmental gradients. We compared four different model shapes and found that the Michaelis-Menten shape was most appropriate for the tree biomass prediction. Model parameter values were significantly different from one forest plot to another, and this leads to large errors in biomass estimates. Variables from the forest stand structure explained a sufficient part of plot-to-plot variations of the height model parameters to improve the quality of the AGB predictions. In the forest stands dominated by small trees, the trees were found to have rapid height growth for small diameters. In forest stands dominated by larger trees, the trees were found to have the greatest heights for large diameters. The aboveground biomass estimation uncertainty of the forest plots was reduced by the use of the forest structure-based height model. It demonstrated the feasibility and the importance of height modeling in tropical forests for carbon mapping. When the tree heights are not measured in an inventory, they can be predicted with a height-diameter model and incorporating forest structure descriptors may improve the predictions. © Author(s) 2014. CC Attribution 3.0 License. |
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Université de Liège, Liège, Belgium |
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European Geosciences Union |
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17264189 (Issn) |
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Export Date: 3 July 2014; Correspondence Address: Molto, Q.; Université des Antilles et de la Guyane, UMR Ecologie des Forêts de Guyane, Kourou, France; email: quentin.molto@gmail.com |
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EcoFoG @ webmaster @ |
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550 |
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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 |
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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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Year |
2021 |
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Geoscientific Model Development |
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14 |
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6 |
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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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Picard, N.; Mortier, F.; Rossi, V.; Gourlet-Fleury, S. |
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Title |
Clustering species using a model of population dynamics and aggregation theory |
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Journal Article |
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Year |
2010 |
Publication |
Ecological Modelling |
Abbreviated Journal |
Ecol. Model. |
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Volume |
221 |
Issue |
2 |
Pages |
152-160 |
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Keywords |
Aggregation theory; Species grouping; Species richness; Tropical rainforest; Usher model |
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The high species diversity of some ecosystems like tropical rainforests goes in pair with the scarcity of data for most species. This hinders the development of models that require enough data for fitting. The solution commonly adopted by modellers consists in grouping species to form more sizeable data sets. Classical methods for grouping species such as hierarchical cluster analysis do not take account of the variability of the species characteristics used for clustering. In this study a clustering method based on aggregation theory is presented. It takes account of the variability of species characteristics by searching for the grouping that minimizes the quadratic error (square bias plus variance) of some model's prediction. This method allows one to check whether the gain in variance brought by data pooling compensate for the bias that it introduces. This method was applied to a data set on 94 tree species in a tropical rainforest in French Guiana, using a Usher matrix model to predict species dynamics. An optimal trade-off between bias and variance was found when grouping species. Grouping species appeared to decrease the quadratic error, except when the number of groups was very small. This clustering method yielded species groups similar to those of the hierarchical cluster analysis using Ward's method when variance was small, that is when the number of groups was small. (C) 2009 Elsevier B.V. All rights reserved. |
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[Picard, Nicolas; Mortier, Frederic; Rossi, Vivien; Gourlet-Fleury, Sylvie] CIRAD, F-34398 Montpellier 5, France, Email: nicolas.picard@cirad.fr |
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ELSEVIER SCIENCE BV |
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0304-3800 |
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ISI:000273628800004 |
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EcoFoG @ eric.marcon @ |
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85 |
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van Gorsel, E.; Delpierre, N.; Leuning, R.; Black, A.; Munger, J.W.; Wofsy, S.; Aubinet, M.; Feigenwinter, C.; Beringer, J.; Bonal, D.; Chen, B.Z.; Chen, J.Q.; Clement, R.; Davis, K.J.; Desai, A.R.; Dragoni, D.; Etzold, S.; Grunwald, T.; Gu, L.H.; Heinesch, B.; Hutyra, L.R.; Jans, W.W.P.; Kutsch, W.; Law, B.E.; Leclerc, M.Y.; Mammarella, I.; Montagnani, L.; Noormets, A.; Rebmann, C.; Wharton, S. |
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Title |
Estimating nocturnal ecosystem respiration from the vertical turbulent flux and change in storage of CO2 |
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Journal Article |
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Year |
2009 |
Publication |
Agricultural and Forest Meteorology |
Abbreviated Journal |
Agric. For. Meteorol. |
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149 |
Issue |
11 |
Pages |
1919-1930 |
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Ecosystem respiration; Micrometeorology; Advection; u-star correction; Eddy covariance; Chamber; Process-based modelling |
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Micrometeorological measurements of night time ecosystem respiration can be systematically biased when stable atmospheric conditions lead to drainage flows associated with decoupling of air flow above and within plant canopies. The associated horizontal and vertical advective fluxes cannot be measured using instrumentation on the single towers typically used at micrometeorological sites. A common approach to minimize bias is to use a threshold in friction velocity, u*, to exclude periods when advection is assumed to be important, but this is problematic in situations when in-canopy flows are decoupled from the flow above. Using data from 25 flux stations in a wide variety of forest ecosystems globally, we examine the generality of a novel approach to estimating nocturnal respiration developed by van Gorsel et al. (van Gorsel, E., Leuning, R., Cleugh, H.A., Keith, H., Suni, T., 2007. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u*-threshold filtering technique. Tellus 59B, 397-403, Tellus, 59B, 307-403). The approach is based on the assumption that advection is small relative to the vertical turbulent flux (F-C) and change in storage (F-S) of CO2 in the few hours after sundown. The sum of F-C and F-S reach a maximum during this period which is used to derive a temperature response function for ecosystem respiration. Measured hourly soil temperatures are then used with this function to estimate respiration R-Rmax. The new approach yielded excellent agreement with (1) independent measurements using respiration chambers, (2) with estimates using ecosystem light-response curves of F-c + F-s extrapolated to zero light, R-LRC, and (3) with a detailed process-based forest ecosystem model, R-cast. At most sites respiration rates estimated using the u*-filter, R-ust, were smaller than R-Rmax, and R-LRC. Agreement of our approach with independent measurements indicates that R-Rmax, provides an excellent estimate of nighttime ecosystem respiration. (C) 2009 Elsevier B.V. All rights reserved. |
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[van Gorsel, Eva; Leuning, Ray] CSIRO Marine & Atmospher Res, Canberra, ACT 2061, Australia, Email: Eva.vangorsel@csiro.au |
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ELSEVIER SCIENCE BV |
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0168-1923 |
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ISI:000270640300013 |
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EcoFoG @ eric.marcon @ |
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102 |
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Jabiol, J.; Corbara, B.; Dejean, A.; Cereghino, R. |
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Structure of aquatic insect communities in tank-bromeliads in a East-Amazonian rainforest in French Guiana |
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Journal Article |
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2009 |
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Forest Ecology and Management |
Abbreviated Journal |
For. Ecol. Manage. |
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257 |
Issue |
1 |
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351-360 |
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Bromeliaceae; Classification; Community structure; Insects; Microcosms; Neural networks; Nouragues; Phytotelmata; Species richness |
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Tank-bromeliads are discrete habitats which contain distinct aquatic communities, and which commonly occur in the neotropics. Because they span a broad range of ecological gradients in terms of habitat structure and amount of resources, researchers study the associations between the biodiversity of communities and these gradients in rainforests, where the very high species richness and densities within other continuous habitats makes it difficult to quantify animal communities. We analysed the diversity of aquatic insect communities in relation to different tank-bromeliad species in a primary rainforest (French Guiana) using artificial intelligence and complex optimization techniques to classify communities and model their determinants. First, the self-organizing map (neural network) was used to classify 158 bromeliads according to the quantitative structure of the insect communities. Catopsis berteroniana and Guzmania lingulata formed separate clusters of plants on the virtual map, while Vriesea splendens, Vriesea pleiosticha and Aechmea melinonii were grouped together in the remaining clusters. Some insect taxa occurred in all bromeliads, while other taxa were specific to a given species. Second, general linear modelling allowed us to specify the influence of the bromeliad species; water volume and volume of fine particulate organic matter inside of the tank; elevation above the ground; and sampling site on taxonomic richness and insect abundance. The number of taxa and individuals per plant increased with greater water volume, but the slope of the relationships depended on the bromeliad species. The significant influence of bromeliad species suggested that at similar water volumes different plant species had different taxon richness and insect abundance. Greater amounts of fine particulate organic matter were detrimental to community diversity in the tanks, probably because they decreased available space by clogging it and/or affected oxygen concentrations. The influence of tank-bromeliad species on the aquatic insect community was primarily related to their physical (and probably chemical) features rather than to species-specific associations sensu stricto. The classification of bromeliads with respect to animal species is likely to provide referential schemes for those biodiversity patterns to be expected under certain conditions, and may help to target model communities for subsequent experimental research. (C) 2008 Elsevier B,V. All rights reserved. |
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[Jabiol, J.; Cereghino, R.] Univ Toulouse 3, Ecolab, Lab Ecol Fonctionnelle, CNRS,UMR 5245, F-31062 Toulouse 9, France, Email: cereghin@cict.fr |
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ELSEVIER SCIENCE BV |
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0378-1127 |
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ISI:000261856000038 |
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EcoFoG @ eric.marcon @ |
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124 |
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Scotti, I.; Gugerli, F.; Pastorelli, R.; Sebastiani, F.; Vendramin, G.G. |
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Maternally and paternally inherited molecular markers elucidate population patterns and inferred dispersal processes on a small scale within a subalpine stand of Norway spruce (Picea abies [L.] Karst.) |
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Journal Article |
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Year |
2008 |
Publication |
Forest Ecology and Management |
Abbreviated Journal |
For. Ecol. Manage. |
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Volume |
255 |
Issue |
11 |
Pages |
3806-3812 |
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chloroplast microsatellites; mitochondrial minisatellites; pollen/seed dispersal; demography; spatial autocorrelation |
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The within-population spatial structure of genetic diversity is shaped by demographic processes, including historical accidents such as forest perturbations. Information drawn from the analysis of the spatial distribution of genetic diversity is therefore inherently linked to demographic-historical processes that ultimately determine the fate of populations. All adult trees and saplings in a 1.4-ha plot within a mixed Norway spruce (Picea abies [L.] Karst) stand were characterised by means of chloroplast (paternally inherited) markers, and a large sub-sample of these were genotyped at mitochondrial (maternally inherited) molecular markers. These data were used to analyse the spatial distribution of genetic variation and to compare the patterns corresponding to the two marker types. The plot presented non-homogeneous local stem density in the younger cohorts, and the indirect effect of this source of variation on the spatial genetic structure was investigated. Results suggest that (i) spatially limited seed dispersal induced patchiness in genotype distribution, while pollen flow had a homogenising effect; (ii) deviations from random spatial structure were stronger in the demographically most stable portions of the stand, while they were weaker where sudden bursts of regeneration occurred; (iii) spatially overlapping adult and sapling cohorts displayed the same spatial genetic structure (stronger on stable areas, weaker in portions of the stand undergoing events of intense regeneration), which was substantiated by the influence of local demographic processes. Regeneration dynamics as modulated by demography thus influences the distribution of genetic diversity within the stand both in the younger life stages and in the adult population. (C) 2008 Elsevier B.V. All rights reserved. |
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[Scotti, I.] INRA, UMR 0745, ECOFOG, F-97387 Kourou, France, Email: ivan.scotti@kourou.cirad.fr |
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ELSEVIER SCIENCE BV |
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0378-1127 |
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ISI:000257019100019 |
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EcoFoG @ eric.marcon @ |
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137 |
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Rockwell, C.A.; Kainer, K.A.; Staudhammer, C.L.; Baraloto, C. |
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Future crop tree damage in a certified community forest in southwestern Amazonia |
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Journal Article |
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2007 |
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Forest Ecology and Management |
Abbreviated Journal |
For. Ecol. Manage. |
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242 |
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2-3 |
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108-118 |
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bamboo; community forest management; forest certification; Guadua; liana; marking; reduced-impact logging; RIL; timber management; tropical forest |
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Field studies in Acre, Brazil assessed logging impacts of a certified community timber management project. The main objectives of the study were: (1) to determine if damage incidence to future crop trees (FCTs; >= 20 cm diameter at breast height (dbh)) differs between (a) forest with and without bamboo (Guadua spp.), and (b) trees with and without lianas; (2) to what extent harvesting can be conducted more intensely (m(3)ha(-1)), without incurring greater FCT damage; and (3) to what extent marking diminishes FCT damage. Full inventories of FCTs of 50 commercial species complexes were conducted before and after logging in 50 m-radius zones of impact around each designated harvest tree in three 10 ha (200 m x 500 m) logging blocks. We also mapped all forested areas potentially influenced by logging, including skid trails, log landings and felling gaps, throughout the 30 ha logged. More than 28% of the forest area was disturbed by logging, with 12.1% in skid trails and 16.8% in gap clearings, indicating that the forest gap mosaic can be significantly altered even when reduced-impact logging guidelines are followed. Overall, 15% of FCTs inventoried were damaged. Damage rates were not significantly reduced by marking treatment, location in bamboo-dominated forest, or liana load on FCT damage. Harvest intensity did not influence the probability of FCT damage. For future studies, it would be prudent to address impacts of timber extraction on other livelihood activities, such as non-timber forest product collection, particularly in such regions as the Brazilian Amazon, where many communities are attempting to integrate a suite of income-generating activities. (C) 2007 Elsevier B.V. All rights reserved. |
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Univ Florida, Sch Forest Resources & Conservat, Gainesville, FL 32611 USA, Email: crockwel@ufl.edu |
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ELSEVIER SCIENCE BV |
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0378-1127 |
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ISI:000246268100003 |
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EcoFoG @ eric.marcon @ |
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217 |
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Schimann, H.; Joffre, R.; Roggy, J.C.; Lensi, R.; Domenach, A.M. |
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Evaluation of the recovery of microbial functions during soil restoration using near-infrared spectroscopy |
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Journal Article |
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2007 |
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Applied Soil Ecology |
Abbreviated Journal |
Appl. Soil Ecol. |
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37 |
Issue |
3 |
Pages |
223-232 |
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NIRS; microbial activities; respiration; denitrification; carbon; nitrogen; soil functioning; restoration |
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Abstract |
Microbial-based indicators, such as C and N contents or microbial functions involved in C and N cycles, are currently used to describe the status of soils in disturbed areas. Microbial functions are more accurate indicators but their measurement for studies at the ecosystem level remains problematical because of the huge spatial variability of these processes and, consequently, of the large number of soil samples which must be analyzed. Our goal was to test the capacity of near-infrared reflectance spectroscopy (NIRS) to predict respiration and denitrification but also carbon and nitrogen contents of soils submitted to various procedures of restoration. To achieve this objective, we took advantage of an experiment conducted on a reforestation system established after open-cast gold mining in French Guiana. In this experimental station, plantations of various ages and various soil textures were at our disposal. Our results showed that both plantations and soil texture had a strong impact on the recovery of soil functioning: carbon and nitrogen contents, respiration and denitrification increased with age of plantation and clay content. Calibrations were performed between spectral data and microbial-based indicators using partial least squares regression (PLS). The results showed that C and N contents were accurately predicted. Microbial functions were less precisely predicted with results more accurate on clayey soils than on sandy soils. In clayey soils, perturbed or restored soils and the year of plantation were discriminated very efficiently through principal component analyses of spectral signatures (over 80% of variance explained on the first two axes). Near-infrared spectroscopy may thus be extended to the prediction of functional soil parameters, but the capacity of this method must be strengthened by expending the databases with other soils in other contexts. The possibility of using NIRS provides many opportunities for understanding both the temporal dynamics and the spatial variability of the recovery of key microbial functions during soil restoration. (c) 2007 Elsevier B.V. All rights reserved. |
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UMR EcoFoG, Kourou 97387, French Guiana, Email: heidy.schimann@cirad.fr |
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ELSEVIER SCIENCE BV |
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0929-1393 |
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ISI:000250668000006 |
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EcoFoG @ eric.marcon @ |
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154 |
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Author |
Sierra, J.; Daudin, D.; Domenach, A.M.; Nygren, P.; Desfontaines, L. |
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Title |
Nitrogen transfer from a legume tree to the associated grass estimated by the isotopic signature of tree root exudates: A comparison of the N-15 leaf feeding and natural N-15 abundance methods |
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Journal Article |
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2007 |
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European Journal of Agronomy |
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Eur. J. Agron. |
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27 |
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2-4 |
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178-186 |
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agroforestry; box model; gliricidia sepium; N-15 fractionation; root turnover; tree pruning |
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Nitrogen (N) transfer from legume trees to associated crops is a key factor for the N economy of low-input agroforestry systems. In this work, we presented a new approach to estimate N transfer based on the N-15 content of root exudates and N released by root turnover of the donor plant (Gliricidia sepium) and the temporal change of the N-15 content of the receiver plant (Dichanthium aristatum). The study was carried out in greenhouse using two isotopic methods: N-15 leaf feeding (LF) and the natural N-15 abundance (NA). Measurements of exudate N-15 were made at several dates before and after tree pruning. A time-dependent box model was devised to quantify N transfer in time and to make comparisons between the isotopic methods. In NA, although tree roots and exudates presented a similar N-15 signature before tree pruning, exudates were strongly depleted in N-15 after pruning. In LF, exudates were always depleted in N-15 in relation to tree roots. Hence, the current assumption used in N transfer studies concerning the equal N-15/N-14 distribution in tissues of the donor plant and in its excreted N was not confirmed in our study. Before pruning, N transfer functioned as a two-N-source system (soil N and exudates N) and both isotopic methods provided similar estimates: 11-12% for LF and 10-15% for NA. Calculations per-formed with the model indicated that N transfer occurred with small or nil fractionation of N-15 in exudates. After pruning, there was a third N source associated with N released from tree root turnover. During this period, the isotopic signature of the receiver plant showed a transient state due to the progressive decrease of N-15 content of that N source. The amount of N derived from the tree represented 65% of the total N content of the. grass at the end of the experiments. (c) 2007 Elsevier B.V. All rights reserved. |
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INRA, Unite Agropedioclimat, UR135, Petit Bourg 97170, Guadeloupe, Email: jorge.sierra@antilles.inra.fr |
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ELSEVIER SCIENCE BV |
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1161-0301 |
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ISI:000249798900003 |
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EcoFoG @ eric.marcon @ |
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157 |
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