Duminil, J., Caron, H., Scotti, I., Cazal, S. O., & Petit, R. J. (2006). Blind population genetics survey of tropical rainforest trees. Mol. Ecol., 15(12), 3505–3513.
Abstract: Rainforest tree species can be difficult to identify outside of their period of reproduction. Vascular tissues from Carapa spp. individuals were collected during a short field trip in French Guiana and analysed in the laboratory with nuclear and chloroplast markers. Using a Bayesian approach, > 90% of the samples could be assigned to one of two distinct clusters corresponding to previously described species, making it possible to estimate the genetic structure of each species and to identify cases of introgression. We argue that this blind procedure represents a first-choice rather than a fallback option whenever related taxa are investigated.
Keywords: Bayesian assignment tests; genetic diversity; geographical structure; South America; species delimitation
|
Dulormne, M., Musseau, O., Muller, F., Toribio, A., & Bâ, A. (2010). Effects of NaCl on growth, water status, N2 fixation, and ion distribution in Pterocarpus officinalis seedlings. Plant and Soil, 327(1), 23–34.
Abstract: Pterocarpus officinalis (Fabaceae) dominates in the swamp forests of the Lesser Antilles, submitted to strong variations of soil salinity (30-445 mM). This study aimed to assess the effect of salinity on growth, nodulation, N2 fixation, water status and ions content in P. officinalis and to clarify the mechanisms involved. Seedlings inoculated or not with two strains from areas of contrasting salinity levels (< to 50 or 445 mM) were watered with 0, 171 and 342 mM solutions of NaCl in greenhouse conditions. Non-inoculated seedlings were tolerant to a salinity of 171 mM, with no significant effect on seedling biomass. Evapotranspiration per unit of leaf area (E/TLa) remained unchanged at 171 mM. Maintenance of a constant E/TLa and especially the control of ion transport to the upper parts of the plant could explain seedling salt tolerance up to intermediate salinity conditions (171 mM). The two strains have a 99.8% genetic identity in spite of differences in their original habitats, this explaining the similar response of the symbiosis to salinity. The higher salt sensitivity of inoculated seedlings was linked to the sensitivity of both Bradyrhizobium strains (reduction of free-living cells) and to that of the nodulation process (fewer nodules and inhibition of N2-fixation) to intermediate salinity. © Springer Science + Business Media B.V. 2009.
Keywords: Bradyrhizobium; Leaf water potential; Nodulation; Salt; Swamp forest
|
Dubois-Fernandez, P. C., Le Toan, T., Daniel, S., Oriot, H., Chave, J., Blanc, L., et al. (2012). The tropiSAR airborne campaign in French Guiana: Objectives, description, and observed temporal behavior of the backscatter signal. IEEE Trans Geosci Remote Sens, 50(8), 3228–3241.
Abstract: The TropiSAR campaign has been conducted in August 2009 in French Guiana with the ONERA airborne radar system SETHI. The main objective of this campaign was to collect data to support the Phase A of the 7th Earth Explorer candidate mission, BIOMASS. Several specific questions needed to be addressed to consolidate the mission concept following the Phase 0 studies, and the data collection strategy was constructed accordingly. More specifically, a tropical forest data set was required in order to provide test data for the evaluation of the foreseen inversion algorithms and data products. The paper provides a description of the resulting data set which is now available through the European Space Agency website under the airborne campaign link. First results from the TropiSAR database analysis are presented with two in-depth analyses about both the temporal radiometric variation and temporal coherence at P-band. The temporal variations of the backscatter values are less than 0.5 dB throughout the campaign, and the coherence values are observed to stay high even after 22 days. These results are essential for the BIOMASS mission. The observed temporal stability of the backscatter is a good indicator of the expected robustness of the biomass estimation in tropical forests, from cross-polarized backscatter values as regarding environmental changes such as soil moisture. The high temporal coherence observed after a 22-day period is a prerequisite for SAR Polarimetric Interferometry and Tomographic applications in a single satellite configuration. The conclusion then summarizes the paper and identifies the next steps in the analysis. © 2012 IEEE.
Keywords: Forestry; interferometry; polarimetric synthetic aperture radar
|
Doughty, C. E., Wolf, A., Baraloto, C., & Malhi, Y. (2016). Interdependency of plants and animals in controlling the sodium balance of ecosystems and the impacts of global defaunation. Ecography, 39(2), 204–212.
Abstract: Sodium, an element which is needed by animals but often toxic in high concentrations to plants, may be deficient and limit animal abundance in inland continental regions, but may be overabundant and limit plant productivity in coastal regions. Here we present data from 50 independent plots (including leaf data from more than 2480 individual trees) showing that leaves in the Amazon basin uptake high amounts of sodium (Na) in a manner more similar to the essential cation potassium (K) than to the toxic cation aluminium (Al). Leaf Na increases linearly with soil Na concentrations, and there is no apparent mechanism for selective exclusion of Na in comparison to K, a key attribute of halophytes. This indicates that the Amazon basin is broadly non-halophytic and increased sodium concentrations in non-halophyte plants often decrease plant productivity. Total Na concentrations are ∼ 10 times higher in coastal regions than inland regions. Such concentration gradients in nutrients may have been reduced in the past because large animals that were abundant in the Pleistocene have been hypothesized to play a large role in reducing nutrient concentration gradients at continental scales. We use a diffusion model and a Na loss rate based on empirical data to estimate that large animals may have moved significant quantities of Na inland away from coastal regions in the Amazon Basin. Therefore, our simple model suggests that large animals may play an important, yet diminishing, role in maintaining the sodium balance of the planet. © 2016 Nordic Society Oikos.
|
Donald, J., Murienne, J., Chave, J., Iribar, A., Louisanna, E., Manzi, S., et al. (2021). Multi-taxa environmental DNA inventories reveal distinct taxonomic and functional diversity in urban tropical forest fragments. Global Ecology and Conservation, (29), e01724.
Abstract: Urban expansion and associated habitat transformation drives shifts in biodiversity, with declines in taxonomic and functional diversity. Forests fragments within urban landscapes offer a number of ecosystem services, and help to maintain biodiversity and ecosystem functions. Here, we focus on a tropical forest environment, and on the soil biota. Using eDNA metabarcoding, we compare forest fragments within the city of Cayenne, French Guiana, with a neighbouring continuous undisturbed forest. We wished to determine if urban forest fragments conserve high levels of alpha and beta diversity as well as similar functional composition for plants, soil animals, fungi and bacteria. We found that alpha diversity is similar across habitats for plants and fungi, lower in urban forests for metazoans and higher for bacteria. We also found that urban forests communities differ from undisturbed forests in their taxonomic composition, with urban forests exhibiting greater turnover between fragments potentially caused by ecological drift and limited dispersal. However, their functional composition exhibited limited differences, with an enrichment of palms, arbuscular mycorrhizal fungi and bacteria and a depletion of climber plants and termites. Thus, although urban forest fragments do shelter soil biodiversity that differs from native forests, the losses of soil functions may be relatively limited. This study demonstrates the strong potential of a multi-taxa eDNA approach for rapid inventories across taxonomic kingdoms, in particular for cryptic soil diversity. It also demonstrates the key role of urban forest fragments in conserving biodiversity and ecosystem function, and points to a need for more systematic monitoring of these areas in urban management plans.
|
Donald, J., Maxfield, P., Leroy, C., & Ellwood, M. D. F. (2020). Epiphytic suspended soils from Borneo and Amazonia differ in their microbial community composition. Acta Oecol., 106.
Abstract: Microbial organisms support the high species diversity associated with tropical forests, and likely drive functional processes, but microorganisms found in rainforest canopies are not well understood. We quantified the microbial diversity of suspended soils from two classical epiphytic model systems (bromeliads & bird's nest ferns) across two localities: the Nouragues Reserve in French Guiana and Danum Valley in Malaysian Borneo. Non-epiphytic suspended soils were also collected as controls at the Nouragues Reserve. Effects of epiphyte type and sample location on microbial community composition were determined using Phospholipid Fatty Acid (PLFA) analysis. Total microbial biomass remained constant across the suspended soil types, but PLFA peaks denoting the relative abundance of different microbes varied between bromeliads, bird's nest ferns and non-epiphytic control soils. Suspended soils associated with bird's nest ferns from Borneo contained a microbial community significantly different in composition from those of congeneric bird's nest ferns from Amazonia, due to shifts in the relative abundance of fungi and bacteria. Our findings reveal that epiphytes create convergent niches for microorganisms in tropical canopies, while highlighting the sensitive nature of suspended soil microbial communities. © 2020 Elsevier Masson SAS
Keywords: Asplenium; Bacteria; Borneo; Bromeliaceae; Canopy; French Guiana; Fungi; Plfa; Rainforest; bacterium; community composition; epiphyte; fungus; microbial community; niche; relative abundance; soil microorganism; species diversity; tropical forest; Amazonia; Borneo; Danum Valley; East Malaysia; French Guiana; Malaysia; Nouragues; Sabah; Asplenium; Asplenium nidus; Aves; Bacteria (microorganisms); Bromeliaceae; Fungi
|
Do, N. A., Dias, D., Zhang, Z., Huang, X., Nguyen, T. T., Pham, V. V., et al. (2020). Study on the behavior of squared and sub-rectangular tunnels using the Hyperstatic Reaction Method. Transp. Geotech., 22(100321).
Keywords: Finite element method; Lining; Squared shape; Sub-rectangular shape; Tunnel; efficiency measurement; finite element method; numerical model; transportation development; transportation planning; tunnel design; tunnel lining
|
Dlouhá, J., Alméras, T., Beauchene, J., Clair, B., & Fournier, M. (2018). Biophysical dependences among functional wood traits. Funct Ecol, 32(12), 2652–2665.
Abstract: Abstract Wood properties and especially wood density have been used as functional traits organized along major axes of species life history and strategy. Beyond statistical analyses, a better mechanistic understanding of relationships among wood traits is essential for ecologically relevant interpretation of wood trait variations. A set of theoretical relationships mechanistically linking wood basic density with some other wood traits is derived from cellular material physics. These theoretical models picture basic physical constraints and thus provide null hypotheses for further ecological studies. Analysis is applied to data from two original datasets and several datasets extracted from the literature. Results emphasize the strong physical constraint behind the link between basic density and maximal storable water on the one hand, and elastic modulus on the other hand. Beyond these basic physical constraints, the developed framework reveals physically less expected trends: the amount of free water available for physiological needs increases in less dense wood of fast-growing species, and the cell wall stiffness decreases with density in temperate hardwoods and is higher in sapling stages in the rainforest understorey where competition for light is associated with high mechanical risk. We emphasize the use of theoretically independent traits derived from models of cellular material physics to investigate the functional variation of wood traits together with their environmental and phylogenetic variations. Although the current study is limited to basic density, green wood lumen saturation and wood specific modulus, we further emphasize the identification of complementary independent wood traits representing other biomechanical functions, nutrient storage, hydraulic conductance and resistance to drought. A plain language summary is available for this article.
Keywords: basic density; biomechanical traits; hydraulic traits; wood traits
|
|
Djenontin Tindo, S., Amusant, N., Dangou, J., Wotto, D. V., Avlessi, F., Dahouénon-Ahoussi, E., et al. (2012). Screening of Repellent, Termiticidal and Preventive activities on Wood, of Azadirachta indica and Carapa procera (Meliaceae) seeds oils. ISCA J. Biological Sci., 1(3), 25–29.
|
Diatta, B. D., Niass, O., Diouf, M., Guéye, M., Houel, E., & Boetsch, G. (2021). Diversité et composition phytochimique des bâtonnets frotte-dents (cure-dents) proposés chez les Peul de la commune de Tessékéré (Ferlo Nord, Sénégal). Journal of Applied Biosciences, 158, 16267–16281.
Abstract: Objectifs : Le but de cette étude était de déterminer la composition phytochimique et la teneur en grandes classes chimiques des tiges les plus utilisées comme bâtonnets frotte-dents chez les peul de Widou Thiengoli au Nord Ferlo (Sénégal). Méthodes et résultats : Des entretiens ouverts semi structurés ont permis de recueillir les plantes les plus utilisées. L’indice de fidélité renseigne sur la convergence des usages quant à l’emploi des plantes comme bâtonnets frotte-dent comparé aux autres pratiques cosmétiques. L’étude de la composition phytochimique des tiges a ciblé 8 classes chimiques. Les tanins et les saponines sont très fréquents ; les terpénoïdes et les leuco-anthocyanines presque inexistants. Un dosage des flavonoïdes, alcaloïdes et polyphénols, réalisé chez des extraits aqueux, a porté sur 12 plantes. Les meilleures teneurs en polyphénols et alcaloïdes sont recueillies chez Anogeissus leiocarpa, et la meilleure en flavonoïdes chez Commiphora africana. Conclusion et applicabilité des résultats : Ces résultats permettent de sélectionner à travers la composition phytochimique des plantes, les espèces présentant de potentielles activités antimicrobiennes, car renfermant des composés phytochimique doués de fonctions germicides, au- delà de la fonction mécanique connue des bâtonnets dans l’élimination de la plaque dentaire.
|
