Amusant, N., Beauchene, J., Fournier, M., Janin, G., & Thevenon, M. F. (2004). Decay resistance in Dicorynia guianensis Amsh.: analysis of inter-tree and intra-tree variability and relations with wood colour. Ann. For. Sci., 61(4), 373–380.
Abstract: Dicorynia guianensis Amsh. is very widespread in the forests of French Guiana and moreover is the leading species harvested in this area, but its main defect remains the great variability of wood durability, especially with respect to fungal decay. The aim of this work was to study this inter- and intra-tree variability in order to identify the parameters responsible for this variation (growth area, height and radial position) within the tree. The resistance decrease from the outer heartwood to the pith. Measurement of colour variation using the CIELAB (L*, a*, b*, C*, h*) system was performed at the intra-tree level to highlight the longitudinal and radial gradients of variation. Dicorynia guianensis becomes less red and dark from the outer to the inner heartwood and from the base to the top. Lastly, variations of colour and durability were correlated: the wood is less resistant the redder and darker it is.
Keywords: Dicorynia guianensis; Amazonian wood; wood colour/decay resistance; heartwood; variability
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Bardet, S., Beauchene, J., & Thibaut, B. (2003). Influence of basic density and temperature on mechanical properties perpendicular to grain of ten wood tropical species. Ann. For. Sci., 60(1), 49–59.
Abstract: The influence of temperature on transverse mechanical properties of 10 tropical species in green condition was studied in radial compression (0 to 99 degreesC), transverse shear with longitudinal-radial shearing plane and rupture of the longitudinal-tangential plane (20 to 80 degreesC). Basic density ranged from 0.21 to 0.91 g cm(-3). Load-displacement curves were characterised by initial rigidity, yield stress, yield strain and strain energy at 20% strain level. The relation between each criterion and basic density was expressed by a power law. The dependency on temperature evidenced a sharp glassy transition, except for the fracture energy only slightly influenced by temperature. An empirical model allowed evaluating a transition temperature between 51 and 69 degreesC, depending on the species and the criterion, which was attributed to lignin. Detailed analysis of the apparent modulus in radial compression suggested that complex relaxation phenomena occur around 10 degreesC and that the rubbery state is not fully reached at 80 degreesC.
Keywords: green wood; tropical wood; transverse mechanical properties; basic density; softening temperature
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Sist, P., Picard, N., & Gourlet-Fleury, S. (2003). Sustainable cutting cycle and yields in a lowland mixed dipterocarp forest of Borneo. Ann. For. Sci., 60(8), 803–814.
Abstract: Based on a 6 year monitoring of the dynamics of a mixed dipterocarp forest in East Borneo (1990-1996), we built a matrix model to predict the sustainable cutting cycle in relation with the extraction and damage rates. Plots were ordered according to three main groups of damage and logging intensity. The first group G1 gathered slightly damaged plots with a remaining basal area greater than or equal to80% of the original (mean logging intensity = 6 trees ha(-1)). Plots belonging to G2, had a remaining basal area varying between 70 and 79% of the original one (mean logging intensity = 8 trees ha(-1)). Finally, G3 gathers highly damaged plots with a remaining basal area < 70% of the original one and a high logging intensity (mean = 14 trees ha(-1)). The mean sustainable cutting cycles predicted in the three groups were significantly different and equal 27, 41 and 89 years in G1, G2 and G3 respectively. However, the respective mean annual extracted volumes were similar: 1.6, 1.8 and 1.4 m(3) ha(-1) year(-1), respectively in G1, G2 and G3. The model suggests that a 40 year cycle, extracting 8 trees ha(-1) (60 m(3) ha(-1)) and an annual volume of 1.5 m(3) ha(-1) year(-1) is the best option to preserve ecological integrity of the forest, to ensure yield sustainability and, according to existing cost analysis, economic profitability. This result is also consistent with other studies which already demonstrated that logging damage reduction using RIL techniques could be only significant with a moderate felling intensity not exceeding 8 trees ha(-1). This felling intensity threshold can be easily achieved by applying simple harvesting rules.
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Vincent, G., Molino, J. F., Marescot, L., Barkaoui, K., Sabatier, D., Freycon, V., et al. (2011). The relative importance of dispersal limitation and habitat preference in shaping spatial distribution of saplings in a tropical moist forest: a case study along a combination of hydromorphic and canopy disturbance gradients. Ann. For. Sci., 68(2), 357–370.
Abstract: Various processes contribute to shaping the local assemblage of species in hyperdiverse tropical forest. The relative contribution of environmental factors and dispersal limitation in determining the spatial distribution of saplings at local scale is unclear. We examined two types of environmental factors: (a) soil type reflecting drainage regime and (b) past logging damages reflecting light regime in a neotropical moist forest site. We used a logistic model to predict presence or absence of a given species in a network of elementary small plots. The effect of mapped environmental factors and a spatial correlation term were jointly estimated providing a direct measure of the relative role of habitat specialisation and dispersal limitation. At community level, dispersal limitation was the most important determinant of species absence at local scale. The two environmental factors examined played a balanced role. Different species however showed different degrees of dispersal limitation and habitat specialisation. The distribution of a large proportion of species-the majority of the most abundant species-was significantly affected by at least one environmental factor. We provide a ranking of 49 species sensitive to canopy disturbance (from shade specialist to pioneer) and 41 species affected by seasonal flooding (either positively or negatively).
Keywords: Species assemblage; Dispersal limitation; Tropical moist forest; Niche
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McLean, J. P., Zhang, T., Bardet, S., Beauchene, J., Thibaut, A., Clair, B., et al. (2011). The decreasing radial wood stiffness pattern of some tropical trees growing in the primary forest is reversed and increases when they are grown in a plantation. Ann. For. Sci., 68(4), 681–688.
Abstract: Background This study examines the radial trend in wood stiffness of tropical rainforest trees. The objective was to determine if the type of growing environment (exposed plantation or dense primary forest) would have an effect on this radial trend. Methods The axial elastic modulus of wood samples, representing a pith to bark cross-section, of six trees from several French Guianese species (two of Eperua falcata, one of Eperua grandiflora, two of Carapa procera and one of Symphonia gloubulifera) was measured using a dynamic “forced vibration” method. Results Primary forest trees were observed to have a decrease in wood stiffness from pith to bark, whereas plantation trees, from the same genus or species, displayed a corresponding increase in wood stiffness. Juvenile wood stiffness appears to vary depending on the environment in which the tree had grown. Conclusion We suggest that the growth strategy of primary forest trees is to produce wood resistant to self-buckling so that the height of the canopy may be obtained with the maximum of efficiency. In contrast, the growth strategy of the trees growing in an exposed plantation is to produce low-stiffness wood, important to provide flexibility in wind. Further experiments to study the behaviour of more species, with more individuals per species, growing across a range of physical environments, are required.
Keywords: Tropical trees; Growth strategy; Wood stiffness; Juvenile wood
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Stahl, C., Burban, B., Goret, J. Y., & Bonal, D. (2011). Seasonal variations in stem CO(2) efflux in the Neotropical rainforest of French Guiana. Ann. For. Sci., 68(4), 771–782.
Abstract: Introduction Stem CO(2) efflux (E (s)) is a significant component of total ecosystem respiration, but there is only scant information on seasonal variations in E (s) in tropical rainforests and on the main factors explaining these variations. Methods We conducted a comprehensive 18-month study in French Guiana to try to better understand which environmental factors contribute to seasonal variations in E (s) in two habitats differing in soil water conditions. Results In both habitats, large seasonal variations in E (s) were observed for most trees. The main variations occurred during climatic transition periods and were consistent with seasonal variations in soil and total ecosystem respiration. Discussion Seasonal variations in atmospheric conditions, including air temperature, did not explain seasonal variations in E (s). In contrast, seasonal variations in surface soil water content clearly induced seasonal variations in E (s) in each habitat. Both soil drought and flooded conditions induced a decrease in E (s). Conclusion Our results emphasize the need to integrate the influence of soil water content on E (s) into global models that simulate the response of forest ecosystem fluxes to climate changes.
Keywords: Tropical rainforest; Stem CO(2) efflux; Soil water content; Terra Firme forest; Seasonally flooded forest
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Niamke, F. B., Amusant, N., Charpentier, J. P., Chaix, G., Baissac, Y., Boutahar, N., et al. (2011). Relationships between biochemical attributes (non-structural carbohydrates and phenolics) and natural durability against fungi in dry teak wood (Tectona grandis L. f.). Ann. For. Sci., 68(1), 201–211.
Abstract: Introduction Non-structural carbohydrates and phenolic compounds are implicated in the natural durability of wood. In order to find the chemical traits of natural durability in teak wood, the radial distribution of phenolics compounds and non-structural carbohydrates were studied in trees ranked by contrasting natural durability class against Antrodia sp. Methods Non-structural carbohydrates were analyzed by spectrophotometry after enzymatic assays and phenolics compounds using HPLC. Results High concentrations of starch, sucrose, glucose, and fructose were found in the sapwood, whereas only trace amounts were found in the heartwood. In the sapwood, low concentrations of H1 (a hydroxycinnamic acid derivative) were specifically detected. Tectoquinone was also detected in the sapwood but its content increased dramatically in the heartwood. 2-(Hydroxymethyl) anthraquinone and P1, an unidentified compound, were only detected in the heartwood and at high concentrations (>3 mg equivalent 5-methoxyflavone g(-1) dry weight. Lower concentrations of 1,4-naphthoquinone, anthraquinone-2-carboxylic acid, and lapachol were also only detected in the heartwood. H1 and tectoquinone present in the sapwood could be considered as phenolic precursors of the synthesis of heartwood toxic phenolics in the heartwood. Conclusion Correlations between natural durability and chemical composition of heartwood (quinone derivatives, P1, and non-structural carbohydrates) suggest that P1, 2-(hydroxymethyl) anthraquinone and tectoquinone could be natural durability traits. Heartwood extractives,
Keywords: Tectona grandis; Teak heartwood; Phenolic compound; Non-structural carbohydrate; Natural durability
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Pickett, K. M., Carpenter, J. M., & Dejean, A. (2009). “Basal” but not primitive: the nest of Apoica arborea de Saussure, 1854 (Insecta, Hymenoptera, Vespidae, Polistinae). Zoosystema, 31(4), 945–948.
Abstract: The first nest of Apoica arborea ever collected is reported. Characteristics of the unusual nest design are discussed relative to other members of the genus Apoica and other epiponine genera. The characteristics of its nest architecture are a mosaic of primitive and derived features for the Polistinae, and thus the nest design is not properly interpreted as the primitive condition from which other swarm-founding wasp nest designs are derived. The frequent conflation of “basal” and primitive is discussed.
Keywords: Insecta; Hymenoptera; Vespidae; Polistinae; Apoica; social wasps; nest architecture; mosaic evolution
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Male, P. J. G., Loiseau, A., Estoup, A., Quilichini, A., & Orivel, J. (2010). Characterization of polymorphic microsatellite loci in the neotropical plant-ant Allomerus decemarticulatus (Formicidae: Myrmicinae) and multiplexing with other microsatellites from the ant subfamily Myrmicinae. Eur. J. Entomol., 107(4), 673–675.
Abstract: Five polymorphic microsatellite loci of the arboreal ant Allomerus decemarticulatus (Myrmicinae) were isolated and characterized. The amplification and polymorphism of seven additional microsatellite loci, previously developed for the ant species A. octoarticulatus and Wasmannia auropunctata, were also tested and the amplification conditions necessary for genotyping the complete set of 12 multiplexed markers in A. decemarticulatus determined. The number of alleles per locus ranged from three to 15 and observed heterozygosity varied front 0.09 to 0.95. Cross-species amplification of these loci was also successfully achieved in additional species of the same ant subfamily, Myrmicinae. This set of microsatellite markers will be used in studies on the mating system and population genetic structure of Myrmicinae in general and A. decemarticulatus in particular.
Keywords: Hymenoptera; Formicidae; Myrmicinae; Allomerus; ant-plant mutualism; microsatellites; plant-ant
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Maron, P. A., Schimann, H., Ranjard, L., Brothier, E., Domenach, A. M., Lensi, R., et al. (2006). Evaluation of quantitative and qualitative recovery of bacterial communities from different soil types by density gradient centrifugation. Eur. J. Soil Biol., 42(2), 65–73.
Abstract: Extracting and purifying a representative fraction of bacteria from soil is necessary for the application of many techniques of microbial ecology. Here the influence of different soil types on the quantitative and qualitative recovery of bacteria by soil grinding and Nycodenz density gradient centrifugation was investigated. Three soils presenting contrasted physicochemical characteristics were used for this study. For each soil, the total (AODC: acridine orange direct count) and culturable (cfa: colony-forming units) bacterial densities were measured in three distinct fractions: (i) the primary soil, (ii) the soil pellet (soil remaining after centrifugation), and (iii) the extracted cells. The automated-ribosomal intergenic spacer analysis (A-RISA) was used to characterize the community structure directly from the DNA extracted from each fraction. The physicochemical characteristics of soils were found to influence both the efficiency of bacterial cell recovery and the representativeness of the extracted cells in term of community structures between the different fractions. Surprisingly, the most representative extracted cells were obtained from the soil exhibiting the lowest efficiency of cell recovery. Our results demonstrated that quantitative and qualitative cell recovery using Nycodenz density gradient centrifugation are not necessarily related and could be differentially biased according to soil type. (c) 2006 Elsevier SAS. All rights reserved.
Keywords: bacterial community; soil; density gradient; DNA fingerprint
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