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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.
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Phillips, P. D., Thompson, I. S., Silva, J. N. M., van Gardingen, P. R., & Degen, B. (2004). Scaling up models of tree competition for tropical forest population genetics simulation. Ecol. Model., 180(2-3), 419–434.
Abstract: Understanding the effects of logging activity on genetic diversity is an important aspect of establishing the sustainability of selective logging management operations in tropical forests. Genetic variation is affected by selective logging directly, through the removal of and damage to trees within the population, and indirectly, through a change in the forest structure and environment in which the remaining population lives. Eco-Gene is a population genetics model applied to tropical forests over a scale of hundreds of hectares. SYMFOR is a modelling framework for individual-based spatially explicit ecological and management models applied to tropical forests over a scale of 0.25 4 ha. We have linked the models to enable simulations using processes involved in both models. To overcome problems of scale, the spatially explicit competition index calculated in SYMFOR simulations has been modelled such that it can be applied at scales representing much larger areas for which the data are not available, as required by Eco-Gene. The competition index is modelled as a distribution on a grid-square basis, and implemented in the linked Eco-Gene/SYMFOR system. Each tree within a grid-square is given a “relative competition” within the distribution, biased according to species. A competition index value is obtained for the tree by transforming the grid-square distribution to be relevant to the size of the tree, and extracting a value according to the tree's relative competition within the distribution. The distribution and each tree's relative competition within it change according to the effects of growth, mortality and logging activity. The model was calibrated using data from the Tapajos region of the Eastern Amazon forest. This paper describes the model, its calibration and validation and the implications of scaling up from an explicit representation to a modelled quantity. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: tropical rain; forest; population genetics; model SYMFOR; eco-gene; scaling up; competition
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Levionnois, S., Coste, S., Nicolini, E., Stahl, C., Morel, H., & Heuret, P. (2020). Scaling of petiole anatomies, mechanics and vasculatures with leaf size in the widespread Neotropical pioneer tree species Cecropia obtusa Trécul (Urticaceae). Tree Physiol., 40(2), 245–258.
Abstract: Although the leaf economic spectrum has deepened our understanding of leaf trait variability, little is known about how leaf traits scale with leaf area. This uncertainty has resulted in the assumption that leaf traits should vary by keeping the same pace of variation with increases in leaf area across the leaf size range. We evaluated the scaling of morphological, tissue-surface and vascular traits with overall leaf area, and the functional significance of such scaling. We examined 1,271 leaves for morphological traits, and 124 leaves for anatomical and hydraulic traits, from 38 trees of Cecropia obtusa Trécul (Urticaceae) in French Guiana. Cecropia is a Neotropical genus of pioneer trees that can exhibit large laminas (0.4 m2 for C. obtusa), with leaf size ranging by two orders of magnitude. We measured (i) tissue fractions within petioles and their second moment of area, (ii) theoretical xylem hydraulic efficiency of petioles and (iii) the extent of leaf vessel widening within the hydraulic path. We found that different scaling of morphological trait variability allows for optimisation of lamina display among larger leaves, especially the positive allometric relationship between lamina area and petiole cross-sectional area. Increasing the fraction of pith is a key factor that increases the geometrical effect of supportive tissues on mechanical rigidity and thereby increases carbon-use efficiency. We found that increasing xylem hydraulic efficiency with vessel size results in lower leaf lamina area: xylem ratios, which also results in potential carbon savings for large leaves. We found that the vessel widening is consistent with hydraulic optimisation models. Leaf size variability modifies scaling of leaf traits in this large-leaved species. © The Author(s) 2020. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permission@oup.com.
Keywords: allometry; leaf size; petiole anatomy; scaling; theoretical hydraulic conductivity; vessel widening; xylem
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Prevost-Boure, N. C., Ngao, J., Berveiller, D., Bonal, D., Damesin, C., Dufrene, E., et al. (2009). Root exclusion through trenching does not affect the isotopic composition of soil CO2 efflux. Plant Soil, 319(1-2), 1–13.
Abstract: Disentangling the autotrophic and heterotrophic components of soil CO2 efflux is critical to understanding the role of soil system in terrestrial carbon (C) cycling. In this study, we combined a stable C-isotope natural abundance approach with the trenched plot method to determine if root exclusion significantly affected the isotopic composition (delta C-13) of soil CO2 efflux (R-S). This study was performed in different forest ecosystems: a tropical rainforest and two temperate broadleaved forests, where trenched plots had previously been installed. At each site, R-S and its delta C-13 (delta C-13(Rs)) tended to be lower in trenched plots than in control plots. Contrary to R-S, delta C-13(Rs) differences were not significant. This observation is consistent with the small differences in delta C-13 measured on organic matter from root, litter and soil. The lack of an effect on delta C-13(Rs) by root exclusion could be from the small difference in delta C-13 between autotrophic and heterotrophic soil respirations, but further investigations are needed because of potential artefacts associated with the root exclusion technique.
Keywords: Stable carbon isotopes; Natural abundance; Soil respiration; Trenched plot; Rainforest; Temperate forest
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Valverde-Barrantes, O. J., Authier, L., Schimann, H., & Baraloto, C. (2021). Root anatomy helps to reconcile observed root trait syndromes in tropical tree species. American Journal of Botany, 108(5), 744–755.
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Hofman, M. P., Hayward, M. W., Heim, M., Marchand, P., Rolandsen, C. M., Mattisson, J., et al. (2019). Right on track? Performance of satellite telemetry in terrestrial wildlife research. PLoS One, 14(5), e0216223.
Abstract: Satellite telemetry is an increasingly utilized technology in wildlife research, and current devices can track individual animal movements at unprecedented spatial and temporal resolutions. However, as we enter the golden age of satellite telemetry, we need an in-depth understanding of the main technological, species-specific and environmental factors that determine the success and failure of satellite tracking devices across species and habitats. Here, we assess the relative influence of such factors on the ability of satellite telemetry units to provide the expected amount and quality of data by analyzing data from over 3,000 devices deployed on 62 terrestrial species in 167 projects worldwide. We evaluate the success rate in obtaining GPS fixes as well as in transferring these fixes to the user and we evaluate failure rates. Average fix success and data transfer rates were high and were generally better predicted by species and unit characteristics, while environmental characteristics influenced the variability of performance. However, 48% of the unit deployments ended prematurely, half of them due to technical failure. Nonetheless, this study shows that the performance of satellite telemetry applications has shown improvements over time, and based on our findings, we provide further recommendations for both users and manufacturers.
Keywords: article; nonhuman; telemetry; terrestrial species; wildlife
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Fox Ramos, A. E., Alcover, C., Evanno, L., Maciuk, A., Litaudon, M., Duplais, C., et al. (2017). Revisiting Previously Investigated Plants: A Molecular Networking-Based Study of Geissospermum laeve. Journal of Natural Products, 80(4), 1007–1014.
Abstract: Three new monoterpene indole alkaloids (1-3) have been isolated from the bark of Geissospermum laeve, together with the known alkaloids (−)-leuconolam (4), geissolosimine (5), and geissospermine (6). The structures of 1-3 were elucidated by analysis of their HRMS and NMR spectroscopic data. The absolute configuration of geissolaevine (1) was deduced from the comparison of experimental and theoretically calculated ECD spectra. The isolation workflow was guided by a molecular networking-based dereplication strategy using an in-house database of monoterpene indole alkaloids. In addition, five known compounds previously undescribed in the Geissospermum genus were dereplicated from the G. laeve alkaloid extract network and were assigned with various levels of identification confidence. The antiparasitic activities against Plasmodium falciparum and Leishmania donovani as well as the cytotoxic activity against the MRC-5 cell line were determined for compounds 1-5. © 2017 The American Chemical Society and American Society of Pharmacognosy.
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Sayer, E. J., Rodtassana, C., Sheldrake, M., Bréchet, L. M., Ashford, O. S., Lopez-Sangil, L., et al. (2020). Revisiting nutrient cycling by litterfall—Insights from 15 years of litter manipulation in old-growth lowland tropical forest. Adv. Ecol. Res., 62, 173–223.
Abstract: The crucial role of tropical forests in the global carbon balance is underpinned by their extraordinarily high biomass and productivity, even though the majority of tropical forests grow on nutrient-poor soils. Nutrient cycling by litterfall has long been considered essential for maintaining high primary productivity in lowland tropical forests but few studies have tested this assumption experimentally. We review and synthesise findings from the Gigante Litter Manipulation Project (GLiMP), a long-term experiment in lowland tropical forest in Panama, Central America, in which litter has been removed from or added to large-scale plots for 15 years. We assessed changes in soil and litter nutrient concentrations in response to the experimental treatments and estimated nutrient return and nutrient use efficiency to indicate changes in nutrient cycling. The soil concentrations of most nutrients increased with litter addition and declined with litter removal. Litter removal altered nitrogen, potassium, manganese and zinc cycling, demonstrating the importance of litter inputs for maintaining the availability of these elements to plants. By contrast, litter addition only altered nitrogen cycling and, despite low concentrations of available soil phosphorus, the effects of litter manipulation on phosphorus cycling were inconsistent. We discuss potential mechanisms underlying the observed changes, and we emphasise the importance of decomposition processes in the forest floor for retaining nutrient elements, which partially decouples nutrient cycling from the mineral soil. Finally, by synthesising GLiMP studies conducted during 15 years of litter manipulation, we highlight key knowledge gaps and avenues for future research into tropical forest nutrient cycling. © 2020 Elsevier Ltd
Keywords: Forest floor; Litter addition; Litter removal; Litterfall; Nutrient cycling; Nutrient use efficiency; Soil fertility; Trace elements; Tropical lowland forest
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Malé, P. - J. G., Ferdy, J. - B., Leroy, C., Roux, O., Lauth, J., Avilez, A., et al. (2014). Retaliation in Response to Castration Promotes a Low Level of Virulence in an Ant-Plant Mutualism. Evol. Biol., 41(1), 22–28.
Abstract: The diversion of a host's energy by a symbiont for its own benefit is a major source of instability in horizontally-transmitted mutualisms. This instability can be counter-balanced by the host's retaliation against exploiters. Such responses are crucial to the maintenance of the relationship. We focus on this issue in an obligate ant-plant mutualism in which the ants are known to partially castrate their host plant. We studied plant responses to various levels of castration in terms of (1) global vegetative investment and (2) investment in myrmecophytic traits. Castration led to a higher plant growth rate, signalling a novel case of gigantism induced by parasitic castration. On the other hand, completely castrated plants produced smaller nesting and food resources (i.e. leaf pouches and extra floral nectaries). Since the number of worker larvae is correlated to the volume of the leaf pouches, such a decrease in the investment in myrmecophytic traits demonstrates for the first time the existence of inducible retaliation mechanisms against too virulent castrating ants. Over time, this mechanism promotes an intermediate level of castration and enhances the stability of the mutualistic relationship by providing the ants with more living space while allowing the plant to reproduce. © 2013 Springer Science+Business Media New York.
Keywords: Allomerus decemarticulatus; Cheater; Evolutionary conflict; Hirtella physophora; Mutualism breakdown; Overexploitation
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Fontaine, S., Stahl, C., Klumpp, K., Picon-Cochard, C., Grise, M. M., Dezécache, C., et al. (2018). Response to Editor to the comment by Schipper and Smith to our paper entitled 'Continuous soil carbon storage of old permanent pastures in Amazonia'. Global Change Biology, 24(3), e732–e733.
Keywords: chronosequence study; continuous C accumulation; deep soil C; eddy covariance; grassland
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