Zaremski, A., Gastonguay, L., Zaremski, C., Chaffanel, F., Le Floch, G., & Beauchene, J. (2013). Capacity of tropical forest soils of french guiana and réunion for depolluting the woods impregnated with biocides. Bois Forets Tropiques, 67(318), 51–58.
Abstract: Wood material for a long time was treated with fungicides or insecticides whose impact on the soil after leaching constitutes a real environmental problem. Nowadays, most of the studies on degradation of these toxic products was carried out with microorganisms which have been isolated in the laboratory. The present study sought to refine the knowledge vis-à-vis these microorganisms, especially wood-destroying fungi degrading pollutants in situ, from which few data are actually available. To decontaminate treated wood, the capacity of wooddestroying microorganisms from tropical forest soils of French Guiana and Reunion was evaluated to degrade toxic biocides. These are pentachlorophenol (PCP) and copper- chromium arsenic based compounds (CCA). Monitoring the degradation of samples of red pine, Pinus resinosa, shows that soils of French Guiana are more efficient than those of Reunion Island in terms of microbial activity vis-àvis these two biocides. A significant difference in loss of mass in specimens of red pine treated with CCA and PCP can range from single to double (respectively 18% and 30%). These findings confirm that CCA is less leacher and less degradable than the PCP by microorganisms in the soil. According to the scale of mass loss in laboratory tests, the wood so treated would be classified very not durable after three years of contact with soil, while the treatment is expected to be very durable.
Keywords: Bioremediation; Copper chromium arsenic(CCA) wood-destroying fungi; Depollution; Loss of mass; Pentachlorophenol(PCP); Treated timber; Tropical soil
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Rossi, V., Dolley, T., Cornu, G., Guitet, S., & Herault, B. (2015). GuyaSim : un outil d’aide à la décision pour l’aménagement d’un territoire forestier, la Guyane. Bois et Forets des Tropiques, 326(4), 67–78.
Abstract: Planning policies for rapid development in French Guiana will require the conversion of forested areas, thus contributing to glo- bal warming. Guiana’s policy-makers will need to integrate the preservation of eco- system services into their planning deci- sions. The GuyaSim project was conduc- ted to produce more in-depth knowledge on these services (carbon sequestration, biodiversity and soil quality) and to trans- fer a software application, GuyaSim, to policy-makers to facilitate the use of this knowledge in the development of plan- ning policies. This article presents the characteristics of the application. Guya- Sim is a freeware package of the GIS type designed initially for local authority plan- ners and forestry departments in French Guiana. The application has two main functions:
information delivery and sup-
port for planning decisions. The informa- tion provided includes socio-economic development scenarios, climate scenarios and valuations of ecosystem services. The decision-support component consists of tools for building planning scenarios (land use changes) and forestry scenarios (log- ging), with information on their environ- mental impacts. The functionalities of the software are currently limited by the state of knowledge on Guiana’s ecosystems. Advances made through current research projects are expected to upgrade the application in the medium term.
Keywords: GIS software; scenarios; ecosystem services; simulator; biodiversity; carbon stock; biomass; logging; deforestation; land use changes; tropical forest; French Guiana
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Amusant, N., Digeon, A., Descroix, L., Bruneau, O., Bezard, V., & Beauchene, J. (2015). Planting rosewood for sustainable essential oil production: Influence of surrounding forest and seed provenance on tree growth and essential oil yields. Bois et Forets des Tropiques, 326(4), 57–65.
Abstract: Essential oil from the Amazonian rosewood tree (Aniba rosaeodora Ducke) is valued as an important aromatic ingredient in luxury perfumes. Due to over-harvesting in recent decades, rosewood is now listed as an endangered species. Rosewood tree planting is now considered a viable alternative to logging as it can support both reforestation and sustainable agriculture thanks to sales of the essential oil extracted. We planted 605 rosewood trees in French Guiana from two seeds of local provenance, in a 5 445 m2 plot surrounded by primary forest. Nine years after planting, we assessed the effect of the position of the tree relative to the surrounding forest and of the seed provenance on dendrometric traits (height, circumference, above ground woody biomass) and hence on the yield of essential oil. Measurements were made on 99 trees. Average growth rates for the young trees were 0.7 m/year in height, 2.5 cm/year in stem circumference and 990.5 kg dry mass/ha/year in aboveground biomass, while essential oil yields ranged from 0.6% to 3.6% with a mean of 2.1%. The position of the tree relative to the surrounding forest was the main factor affecting tree growth and essential oil production: trees located close to the surrounding forest were significantly smaller and accumulated less essential oil due to the reduced availability of light. Seed provenance had less effect on dendrometric traits and essential oil yields. In conclusion, although planting practices will need to be adapted to avoid the edge effects of proximity to the forest, short-rotation cultivation of rosewood trees could be the optimum and most economically attractive system for the production of essential oil.
Keywords: Aniba rosaeodora Ducke; Dendrometric traits; Essential oil yield; French Guiana; Light effect; Plantation; Rosewood; Seed provenance
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Gourlet-Fleury, S., Gazull, L., Bigombe Logo, P., Billand, A., Bolaluembe, P. - C., Boyemba, F., et al. (2017). Are logging concessions a threat to the peatlands in DRC? Bois et Forets des Tropiques, (334), 3–6.
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Morel, H., Lehnebach, R., Cigna, J., Ruelle, J., Nicolini, É., & Beauchene, J. (2018). Basic wood density variations of Parkia velutina Benoist, a long-lived heliophilic Neotropical rainforest tree. Bois et Forets des Tropiques, 335, 59–69.
Abstract: Investigations of basic radial wood density (WD) in tropical trees revealed linear patterns and some curvilinear patterns. Studies usually disregard longitudinal variations, which are often considered to be similar to radial variations. This study aimed to show (1) a new radial curvilinear WD pattern, (2) differences in amplitude between radial and longitudinal gradients and (3) to partition WD variations according to different scales in Parkia velutina, an emergent tree found in Neotropical rain forests. We collected full discs from six felled trees and radial cores from 10 standing trees to check WD variability, plus one dominant axis per tree for analysis of height growth rates. This species showed very high growth rates indicative of heliophilic habits. WD varied from 0.194 to 0.642 g/cm3. Such amplitude is rarely observed within the same tree. Radial variation in WD was curvilinear, with an amplitude generally less than the longitudinal amplitude. Consequently, in mature trees, WD values in the crown were higher than those in the outer trunk. WD variations can be highly significant at different scales. The variance partitioning also revealed that the whole WD range of Parkia velutina is more accurately estimated intra-individually when both longitudinal and radial gradient are covered.
Keywords: Curvilinear pattern; French Guiana; Intra-tree; Tropical species
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Petit, M., Céréghino, R., Carrias, J. - F., Corbara, B., Dezerald, O., Petitclerc, F., et al. (2014). Are ontogenetic shifts in foliar structure and resource acquisition spatially conditioned in tank-bromeliads? Bot J Linn Soc, 175(2), 299–312.
Abstract: The phenotypic plasticity of plants has been explored as a function of either ontogeny (apparent plasticity) or environment (adaptive plasticity), although few studies have analyzed these factors together. In the present study, we take advantage of the dispersal of Aechmea mertensii bromeliads by Camponotus femoratus or Pachycondyla goeldii ants in shaded and sunny environments, respectively, to quantify ontogenetic changes in morphological, foliar, and functional traits, and to analyze ontogenetic and ant species effects on 14 traits. Most of the morphological (plant height, number of leaves), foliar (leaf thickness, leaf mass area, total water content, trichome density), and functional (leaf δ13C) traits differed as a function of ontogeny. Conversely, only leaf δ15N showed an adaptive phenotypic plasticity. On the other hand, plant width, tank width, longest leaf length, stomatal density, and leaf C concentration showed an adaptation to local environment with ontogeny. The exception was leaf N concentration, which showed no trend at all. Aechmea mertensii did not show an abrupt morphological modification such as in heteroblastic bromeliads, although it was characterized by strong, size-related functional modifications for CO2 acquisition. The adaptive phenotypic variation found between the two ant species indicates the spatially conditioned plasticity of A. mertensii in the context of insect-assisted dispersal. However, ant-mediated effects on phenotypic plasticity in A. mertensii are not obvious because ant species and light environment are confounding variables. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 175, 299–312.
Keywords: Aechmea mertensii; Camponotus femoratus; French Guiana; leaf traits; mutualistic ants; natural stable isotopes; ontogeny; Pachycondyla goeldii; phenotypic plasticity; plant morphology
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Ghislain, B., Nicolini, E. - A., Romain, R., Ruelle, J., Yoshinaga, A., Alford, M. H., et al. (2016). Multilayered structure of tension wood cell walls in Salicaceae sensu lato and its taxonomic significance. Bot. J. Linn. Soc., 182(4), 744–756.
Abstract: Salicaceae have been enlarged to include a majority of the species formerly placed in the polyphyletic tropical Flacourtiaceae. Several studies have reported a peculiar and infrequently formed multilayered structure of tension wood in four of the tropical genera. Tension wood is a tissue produced by trees to restore their vertical orientation and most studies have focused on trees developing tension wood by means of cellulose-rich, gelatinous fibres, as in Populus and Salix (Salicaceae s.s.). This study aims to determine if the multilayered structure of tension wood is an anatomical characteristic common in other Salicaceae and, if so, how its distribution correlates to phylogenetic relationships. Therefore, we studied the tension wood of 14 genera of Salicaceae and two genera of Achariaceae, one genus of Goupiaceae and one genus of Lacistemataceae, families closely related to Salicaceae or formerly placed in Flacourtiaceae. Opposite wood and tension wood were compared with light microscopy and three-dimensional laser scanning confocal microscopy. The results indicate that a multilayered structure of tension wood is common in the family except in Salix, Populus and one of their closest relatives, Idesia polycarpa. We suggest that tension wood may be a useful anatomical character in understanding phylogenetic relationships in Salicaceae. Further investigation is still needed on the tension wood of several other putatively close relatives of Salix and Populus, in particular Bennettiodendron, Macrohasseltia and Itoa.
Keywords: Flacourtiaceae; G-layer; multilayered tension wood; reaction wood
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Lehnebach, R., Doumerc, L., Clair, B., & Alméras, T. (2020). Mechanical stress in the inner bark of 15 tropical tree species and the relationship with anatomical structure. Bot., 98(1), 1–8.
Abstract: Recent studies have shown that the inner bark is implicated in the postural control of inclined tree stems through the interaction between wood radial growth and tangential expansion of a trellis fiber network in bark. Assessing the taxonomic extent of this mechanism requires a screening of the diversity in bark anatomy and mechanical stress. The mechanical state of bark was measured in 15 tropical tree species from various botanical families on vertical mature trees, and related to the anatomical structure of the bark. Significant tensile or compressive longitudinal stresses were observed in the stems of most species. Tensile longitudinal stress was observed in various botanical families and was always associated with fibers arranged in a trellis-like structure and strong dilatation of rays. The highest tensile stress was recorded in species with gelatinous fibers forming a treillis. Compressive stress was typically associated with a large amount of sclereids in the bark, supporting the differentiation of sclereids as a potential origin of the generation of longitudinal compressive stresses in bark. In species exhibiting both a fibrous trellis structure and a significant amount of sclereids, the sign of longitudinal stress may depend on the balance between these two mechanisms.
Keywords: Bark anatomical structure; Mechanical stress; Sclereids; Secondary phloem; Tree biomechanics; Tropical species
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Epelboin, L., Bourhy, P., Le Turnier, P., Schaub, R., Mosnier, E., Berlioz-Arthaud, A., et al. (2017). La leptospirose en Guyane française et sur le bouclier des Guyanes. État des connaissances en 2016. Bulletin de la Société de pathologie exotique, 110(3), 165–179.
Abstract: La leptospirose est une zoonose cosmopolite causée par les bactéries du genre Leptospira. Si sa répartition est vaste sur le globe, le climat chaud et humide de la zone intertropicale est particulièrement propice à son expansion. Dans la plupart des départements et territoires français d’outremer, la leptospirose est considérée comme un problème de santé publique. En Guyane, département français situé au nord-est de la forêt amazonienne, elle est considérée comme rare. L’objectif de cette revue est de faire l’état des lieux des connaissances sur la leptospirose humaine et animale en Guyane française et dans les pays environnants. Une recherche exhaustive a été conduite, à travers la littérature médicale indexée et informelle en français, anglais, espagnol et portugais. Ainsi, respectivement dix et quatre publications ont pu être identifiées sur la leptospirose humaine et animale en Guyane, publiées entre 1940 et 1995, sous formes de cas cliniques ou de séries de cas. Les publications concernant cette maladie dans les autres pays du plateau des Guyanes, Venezuela oriental, Guyana, Suriname, et État brésilien de l’Amapá, étaient également rares voire inexistantes. En revanche, les données récentes du centre national de la leptospirose français ont montré une augmentation récente et brutale du nombre de cas dans le département, probablement en partie due à la mise en place d’outils diagnostiques tels que la sérologie IgM Elisa. Il est en fait probable que la leptospirose soit une maladie négligée dans la région, du fait de l’absence d’outils diagnostiques rapidement disponibles, de la méconnaissance des cliniciens de cette pathologie et de l’existence de nombreux autres pathogènes à présentation clinique similaire (paludisme, arboviroses, fièvre Q, toxoplasmose amazonienne). La mise en place d’études de plus grande ampleur sur la leptospirose animale et humaine est nécessaire et urgente pour connaître le véritable poids de cette maladie dans notre région.
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Roux, O., Le Lann, C., van Alphen, J. J. M., & van Baaren, J. (2010). How does heat shock affect the life history traits of adults and progeny of the aphid parasitoid Aphidius avenae (Hymenoptera: Aphidiidae)? Bull. Entomol. Res., 100(5), 543–549.
Abstract: Because insects are ectotherms, their physiology, behaviour and fitness are influenced by the ambient temperature. Any changes in environmental temperatures may impact the fitness and life history traits of insects and, thus, affect population dynamics. Here, we experimentally tested the impact of heat shock on the fitness and life history traits of adults of the aphid parasitoid Aphidius avenae and on the later repercussions for their progeny. Our results show that short exposure (1h) to an elevated temperature (36 degrees C), which is frequently experienced by parasitoids during the summer, resulted in high mortality rates in a parasitoid population and strongly affected the fitness of survivors by drastically reducing reproductive output and triggering a sex-dependent effect on lifespan. Heat stress resulted in greater longevity in surviving females and in shorter longevity in surviving males in comparison with untreated individuals. Viability and the developmental rates of progeny were also affected in a sex-dependent manner. These results underline the ecological importance of the thermal stress response of parasitoid species, not only for survival, but also for maintaining reproductive activities.
Keywords: developmental rate; fecundity; heat stress; longevity; sex-specific effect; parasitic wasp
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