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| Author |
Mahoui,Sihem ; Moulay, Mohamed Said ; Omrane, Abdennebi |
| Title |
Finite element approach to linear parabolic pointwise control problems of incomplete data |
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Journal Article |
| Year |
2020 |
Publication |
International Journal of Systems Science |
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| Volume |
51 |
Issue |
14 |
Pages |
2597-2609 |
Keywords  |
Optimal control problem ; low-regret control ; pointwise control ; finite element method ; a priori error estimates |
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In this paper we give a priori error estimates for finite element approximations of linear parabolicproblems with pointwise control and incomplete data. We discretise the optimal control problemby using piecewise linear and continuous finite elements for the space discretisation of the state,and we use the backward Euler scheme for time discretisation. We prove a priori error estimates forthe state, the adjoint-state as well as for the low-regret pointwise optimal control. |
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TAYLOR & FRANCIS LTD |
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EcoFoG @ webmaster @ |
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935 |
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Urbina, I.; Grau, O.; Sardans, J.; Ninot, J.M.; Peñuelas, J. |
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Encroachment of shrubs into subalpine grasslands in the Pyrenees changes the plant-soil stoichiometry spectrum |
Type |
Journal Article |
| Year |
2020 |
Publication |
Plant and Soil |
Abbreviated Journal |
Plant Soil |
| Volume |
448 |
Issue |
1-2 |
Pages |
37-53 |
| Keywords |
Nutrient stocks; Plant strategy; Plant-soil stoichiometry; Shrub encroachment; Subalpine grassland succession; aboveground biomass; biogeochemical cycle; carbon sequestration; ectomycorrhiza; fungus; grass; nitrogen; nutrient uptake; shrub; soil-vegetation interaction; stoichiometry; subalpine environment; succession; Europe; Pyrenees; Fungi |
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Aims: Shrub encroachment has been reported over a large proportion of the subalpine grasslands across Europe and is expected to have an important impact on the biogeochemical cycle of these ecosystems. We investigated the stoichiometric changes in the plant-soil system along the succession (e.g. increase in encroachment from unencroached grassland to mature shrubland) at two contrasting sites in the Pyrenees. Methods: We analyzed the chemical composition (C, N,15N, P, K, Ca, Mg and Fe) in the soil and in the aboveground plant compartments (leaves, leaf-litter and stems) of the main herbaceous species and shrubs at three contrasting stages of the succession: unencroached grassland, young shrubland and mature shrubland. Results: The plant-soil stoichiometry spectrum differed between the successional stages. Shrub encroachment generally increased the concentration of C and Ca and the C:N ratio and often reduced to concentrations of N, P and K in the leaves and leaf-litter, while several soil nutrient concentrations (N, P, K Ca and Mg) decreased. The stocks of C, N, P, Ca, and Mg in the total aboveground biomass increased with encroachment. Conclusions: Shrub encroachment favored the dominance of long-lived species with low concentrations of N and P in the plant-soil compartments, high C:nutrient ratios in the aboveground biomass and increase the uptake of N through ericoid or ectomycorrhizal fungi. We highlight the role of shrubs in the sequestration of C and nutrients through the allocation to the aboveground biomass. The changes in plant-soil elemental composition and stocks suggest a slowdown of the biogeochemical cycles in the subalpine mountain areas where shrub encroachment occurred. © 2020, Springer Nature Switzerland AG. |
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Biodiversity Research Institute (IRBio) and Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Catalonia, Spain |
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Springer |
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0032079x (Issn) |
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EcoFoG @ webmaster @ |
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983 |
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Van Langenhove, L.; Verryckt, L.T.; Bréchet, L.; Courtois, E.A.; Stahl, C.; Hofhansl, F.; Bauters, M.; Sardans, J.; Boeckx, P.; Fransen, E.; Peñuelas, J.; Janssens, I.A. |
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Atmospheric deposition of elements and its relevance for nutrient budgets of tropical forests |
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Journal Article |
| Year |
2020 |
Publication |
Biogeochemistry |
Abbreviated Journal |
Biogeochemistry |
| Volume |
149 |
Issue |
2 |
Pages |
175-193 |
| Keywords |
Litterfall; Nitrogen; Nutrient cycling; Phosphorus; Potassium; Throughfall; atmospheric deposition; canopy exchange; field method; forest floor; leaching; litterfall; nutrient cycling; phosphorus; potassium; precipitation (climatology); rainforest; tropical forest; French Guiana |
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Atmospheric deposition is an important component of the nutrient cycles of terrestrial ecosystems, but field measurements are especially scarce in tropical regions. In this study we analysed 15 months of precipitation chemistry collected in an old growth tropical forest located in French Guiana. We measured nutrient inputs via bulk precipitation and throughfall and used the canopy budget model to estimate nutrient fluxes via canopy exchange and dry deposition. Based on this method we quantified net fluxes of macronutrients and compared their contribution to internal cycling rates via litterfall. Our results suggest that while atmospheric deposition of nitrogen was relatively high (13 kg ha−1 year−1), and mainly in organic forms, the N inputs via litterfall were an order of magnitude higher. In contrast to nitrogen, we found that atmospheric deposition of phosphorus (0.5 kg ha−1 year−1) supplied up to one third of the annual litterfall input to the forest floor. Most strikingly, combined annual inputs of potassium via atmospheric deposition (14 kg ha−1 year−1) and canopy leaching (22 kg ha−1 year−1) were three times larger than internal nutrient recycling via litterfall (11 kg ha−1 year−1). We conclude that atmospheric deposition of phosphorus and especially potassium may play an important role in sustaining the productivity of this old-growth tropical rainforest. © 2020, Springer Nature Switzerland AG. |
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StatUa Center for Statistics, University of Antwerp, Prinsstraat 13, Antwerp, 2000, Belgium |
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Springer |
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01682563 (Issn) |
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EcoFoG @ webmaster @ |
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964 |
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Vleminckx, J.; Bauman, D.; Demanet, M.; Hardy, O.J.; Doucet, J.-L.; Drouet, T. |
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Past human disturbances and soil fertility both influence the distribution of light-demanding tree species in a Central African tropical forest |
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Journal Article |
| Year |
2020 |
Publication |
Journal of Vegetation Science |
Abbreviated Journal |
J. Veg. Sci. |
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31 |
Issue |
3 |
Pages |
440-453 |
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light-demanding species; moist tropical forests; past human disturbances; shade-bearer species; soil charcoal abundance; soil properties; tree community assemblages; wood-specific gravity; anthropogenic effect; forest canopy; forest ecosystem; shifting cultivation; soil fertility; soil property; tree; tropical forest; Cameroon |
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Questions: In vast areas of Central African forests, the upper canopy is presently dominated by light-demanding tree species. Here, we confront three hypotheses to explain this dominance: (a) these species have expanded their distribution because of widespread past slash-and-burn activities, as suggested by important charcoal amounts recorded in the soils of the region; (b) their abundance is rather explained by soil properties, as this guild establishes preferentially on favourable physico-chemical conditions for rapid growth; (c) soil properties have been substantially influenced by past human disturbances and those two effects cannot be disentangled. Location: Pallisco-CIFM logging concession, southeastern Cameroon (300,000 ha). Methods: We quantified soil charcoal abundance and measured ten soil variables at the basis of 60 target trees that belonged to a list of three long-living pioneer light-demanding (LLP) and four shade-bearer (SB) species. We identified all stems with a diameter at breast height (DBH) ≥ 20 cm within a distance of 15 m around each target tree. Species were characterised by their wood-specific gravity (WSG), which reflected their light requirement. Multiple regression models were used to quantify and test the relative effects of charcoal abundance and soil variables on the mean WSG of the 60 tree communities, as well as the abundance of three guilds: LLP, SB, and non-pioneer light demanders (NPLD). Results: The mean WSG was the only response variable significantly explained by soil variables and charcoal abundance combined. It was significantly negatively associated with soil calcium and Mg content and with charcoal abundance, with soil and charcoal influencing the mean WSG independently. Conclusion: Our study provides evidence that past human disturbances and soil fertility have independently promoted the establishment of light-demanding species in western Central African forests, thereby shedding light on tree community assembly rules in these ecosystems which remain considerably understudied compared to the tropical forests of other continents. © 2020 International Association for Vegetation Science |
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Forest is life, TERRA Teaching and Research Centre, Université de Liège – Gembloux Agro-Bio Tech, Gembloux, Belgium |
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Wiley-Blackwell |
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11009233 (Issn) |
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no |
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EcoFoG @ webmaster @ |
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970 |
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Schmitt, S.; Hérault, B.; Ducouret, É.; Baranger, A.; Tysklind, N.; Heuertz, M.; Marcon, É.; Cazal, S.O.; Derroire, G. |
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Topography consistently drives intra- and inter-specific leaf trait variation within tree species complexes in a Neotropical forest |
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Journal Article |
| Year |
2020 |
Publication |
Oikos |
Abbreviated Journal |
Oikos |
| Volume |
129 |
Issue |
10 |
Pages |
1521-1530 |
| Keywords |
intraspecific variability; leaf traits; Paracou; species complex; syngameon; tropical forests; Bayesian analysis; coexistence; divergence; genetic variation; hierarchical system; leaf area; local adaptation; niche overlap; species diversity; topography; tropical forest; Guyana Shield |
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Tropical forests shelter the highest species diversity worldwide, although genus diversity is lower than expected. In the species-rich genera, species complexes are composed of closely-related species that share large amounts of genetic variation. Despite the key role of species complexes in diversification, evolution and functioning of ecological communities, little is known on why species complexes arise and how they are maintained in Neotropical forests. Examining how individual phenotypes vary along environmental gradients, within and among closely-related species within species complexes, can reveal processes allowing species coexistence within species complexes. We examined leaf functional trait variation with topography in a hyperdiverse tropical forest of the Guiana Shield. We collected leaf functional traits from 766 trees belonging to five species in two species complexes in permanent plots encompassing a diversity of topographic positions. We tested the role of topography on leaf functional trait variation with a hierarchical Bayesian model, controlling for individual tree diameter effect. We show that, mirroring what has been previously observed among species and communities, individual leaf traits covary from acquisitive to conservative strategy within species. Moreover, decreasing wetness from bottomlands to plateaus was associated with a shift of leaf traits from an acquisitive to a conservative strategy both across and within closely-related species. Our results suggest that intraspecific trait variability widens species’ niches and converges at species’ margins where niches overlap, potentially implying local neutral processes. Intraspecific trait variability favors local adaptation and divergence of closely-related species within species complexes. It is potentially maintained through interspecific sharing of genetic variation through hybridization. © 2020 Nordic Society Oikos. Published by John Wiley & Sons Ltd |
| Address |
INRAE, UMR EcoFoG (Agroparistech, CNRS, Cirad, Université des Antilles, Univ. de la Guyane), Kourou, French Guiana |
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Blackwell Publishing Ltd |
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00301299 (Issn) |
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EcoFoG @ webmaster @ |
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950 |
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Laybros, A.; Aubry-Kientz, M.; Féret, J.-B.; Bedeau, C.; Brunaux, O.; Derroire, G.; Vincent, G. |
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Quantitative airborne inventories in dense tropical forest using imaging spectroscopy |
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Journal Article |
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2020 |
Publication |
Remote Sensing |
Abbreviated Journal |
Remote Sens. |
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12 |
Issue |
10 |
Pages |
1577 |
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Hyperspectral; LiDAR; Species diversity; Tropical forest; Cost effectiveness; Discriminant analysis; Infrared devices; Infrared radiation; Logistic regression; Remote sensing; Tropics; Classification accuracy; Classification performance; Linear discriminant analysis; Operational applications; Regularized discriminant analysis; Remote sensing technology; Short wave infrared bands; Visible and near infrared; Forestry |
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Tropical forests have exceptional floristic diversity, but their characterization remains incomplete, in part due to the resource intensity of in-situ assessments. Remote sensing technologies can provide valuable, cost-effective, large-scale insights. This study investigates the combined use of airborne LiDAR and imaging spectroscopy to map tree species at landscape scale in French Guiana. Binary classifiers were developed for each of 20 species using linear discriminant analysis (LDA), regularized discriminant analysis (RDA) and logistic regression (LR). Complementing visible and near infrared (VNIR) spectral bands with short wave infrared (SWIR) bands improved the mean average classification accuracy of the target species from 56.1% to 79.6%. Increasing the number of non-focal species decreased the success rate of target species identification. Classification performance was not significantly affected by impurity rates (confusion between assigned classes) in the non-focal class (up to 5% of bias), provided that an adequate criterion was used for adjusting threshold probability assignment. A limited number of crowns (30 crowns) in each species class was sufficient to retrieve correct labels effectively. Overall canopy area of target species was strongly correlated to their basal area over 118 ha at 1.5 ha resolution, indicating that operational application of the method is a realistic prospect (R2 = 0.75 for six major commercial tree species). © 2020 by the authors. |
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Cirad, UMR EcoFoG (AgroParistech, CNRS, INRAE, Université des Antilles, Université de la Guyane), Kourou, French Guiana, 97379, France |
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Mdpi Ag |
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20724292 (Issn) |
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EcoFoG @ webmaster @ |
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969 |
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Touchard, A.; Aili, S.R.; Téné, N.; Barassé, V.; Klopp, C.; Dejean, A.; Kini, R.M.; Mrinalini; Coquet, L.; Jouenne, T.; Lefranc, B.; Leprince, J.; Escoubas, P.; Nicholson, G.M.; Treilhou, M.; Bonnafé, E. |
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Venom Peptide Repertoire of the European Myrmicine Ant Manica rubida: Identification of Insecticidal Toxins |
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Journal Article |
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2020 |
Publication |
Journal of proteome research |
Abbreviated Journal |
J. Proteome Res. |
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19 |
Issue |
4 |
Pages |
1800-1811 |
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glycosylated toxin; peptidome; polycationic α-helix; predation; pyroglutamate; reversible neurotoxicity |
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Using an integrated transcriptomic and proteomic approach, we characterized the venom peptidome of the European red ant, Manica rubida. We identified 13 “myrmicitoxins” that share sequence similarities with previously identified ant venom peptides, one of them being identified as an EGF-like toxin likely resulting from a threonine residue modified by O-fucosylation. Furthermore, we conducted insecticidal assays of reversed-phase HPLC venom fractions on the blowfly Lucilia caesar, permitting us to identify six myrmicitoxins (i.e., U3-, U10-, U13-, U20-MYRTX-Mri1a, U10-MYRTX-Mri1b, and U10-MYRTX-Mri1c) with an insecticidal activity. Chemically synthesized U10-MYRTX-Mri1a, -Mri1b, -Mri1c, and U20-MYRTX-Mri1a irreversibly paralyzed blowflies at the highest doses tested (30-125 nmol·g-1). U13-MYRTX-Mri1a, the most potent neurotoxic peptide at 1 h, had reversible effects after 24 h (150 nmol·g-1). Finally, U3-MYRTX-Mri1a has no insecticidal activity, even at up to 55 nmol·g-1. Thus, M. rubida employs a paralytic venom rich in linear insecticidal peptides, which likely act by disrupting cell membranes. |
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VenomeTech, 473 Route des Dolines – Villa 3, Valbonne, 06560, France |
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NLM (Medline) |
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15353907 (Issn) |
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Export Date: 20 April 2020 |
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EcoFoG @ webmaster @ |
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927 |
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Perrot, T.; Guillaume, S.; Nadine, A.; Jacques, B.; Philippe, G.; Stéphane, D.; Rodnay, S.; Mélanie, M.-R.; Eric, G. |
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A reverse chemical ecology approach to explore wood natural durability |
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Journal Article |
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2020 |
Publication |
Microbial Biotechnology |
Abbreviated Journal |
Microb. Biotechnol. |
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13 |
Issue |
5 |
Pages |
1673-1677 |
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glutathione transferase; Article; biodegradation; data base; detoxification; ecology; enzyme activity; enzyme metabolism; forest; molecular dynamics; physical parameters; species identification; thermal analysis; Trametes versicolor; wood; wood durability |
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The natural durability of wood species, defined as their inherent resistance to wood-destroying agents, is a complex phenomenon depending on many biotic and abiotic factors. Besides the presence of recalcitrant polymers, the presence of compounds with antimicrobial properties is known to be important to explain wood durability. Based on the advancement in our understanding of fungal detoxification systems, a reverse chemical ecology approach was proposed to explore wood natural durability using fungal glutathione transferases. A set of six glutathione transferases from the white-rot Trametes versicolor were used as targets to test wood extracts from seventeen French Guiana neotropical species. Fluorescent thermal shift assays quantified interactions between fungal glutathione transferases and these extracts. From these data, a model combining this approach and wood density significantly predicts the wood natural durability of the species tested previously using long-term soil bed tests. Overall, our findings confirm that detoxification systems could be used to explore the chemical environment encountered by wood-decaying fungi and also wood natural durability. © 2020 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology. |
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Université de Lorraine, INRAE, LERMAB, Nancy, France |
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John Wiley and Sons Ltd |
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17517907 (Issn) |
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EcoFoG @ webmaster @ |
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955 |
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Romero, G.Q.; Marino, N.A.C.; MacDonald, A.A.M.; Céréghino, R.; Trzcinski, M.K.; Mercado, D.A.; Leroy, C.; Corbara, B.; Farjalla, V.F.; Barberis, I.M.; Dézerald, O.; Hammill, E.; Atwood, T.B.; Piccoli, G.C.O.; Bautista, F.O.; Carrias, J.-F.; Leal, J.S.; Montero, G.; Antiqueira, P.A.P.; Freire, R.; Realpe, E.; Amundrud, S.L.; de Omena, P.M.; Campos, A.B.A.; Kratina, P.; O’Gorman, E.J.; Srivastava, D.S. |
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Extreme rainfall events alter the trophic structure in bromeliad tanks across the Neotropics |
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Journal Article |
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2020 |
Publication |
Nature Communications |
Abbreviated Journal |
Nat. Commun. |
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11 |
Issue |
3215 |
Pages |
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fresh water; rain; fresh water; agricultural intensification; angiosperm; biomass; climate change; ecosystem function; extreme event; food web; freshwater ecosystem; Neotropic Ecozone; precipitation intensity; rainfall; trophic structure; Article; biomass; Central America; controlled study; detritivore; drought; flooding; food web; hydrology; microcosm; Neotropics; nonhuman; precipitation; predator; South America; trophic level; animal; biodiversity; Bromelia; climate change; ecosystem; flooding; food chain; Central America; South America; Animals; Biodiversity; Biomass; Bromelia; Climate Change; Droughts; Ecosystem; Floods; Food Chain; Fresh Water; Hydrology; South America |
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Changes in global and regional precipitation regimes are among the most pervasive components of climate change. Intensification of rainfall cycles, ranging from frequent downpours to severe droughts, could cause widespread, but largely unknown, alterations to trophic structure and ecosystem function. We conducted multi-site coordinated experiments to show how variation in the quantity and evenness of rainfall modulates trophic structure in 210 natural freshwater microcosms (tank bromeliads) across Central and South America (18°N to 29°S). The biomass of smaller organisms (detritivores) was higher under more stable hydrological conditions. Conversely, the biomass of predators was highest when rainfall was uneven, resulting in top-heavy biomass pyramids. These results illustrate how extremes of precipitation, resulting in localized droughts or flooding, can erode the base of freshwater food webs, with negative implications for the stability of trophic dynamics. © 2020, The Author(s). |
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Institute of Biological Sciences, Universidade Federal do Pará, Belém, PA, Brazil |
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Nature Research |
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20411723 (Issn) |
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EcoFoG @ webmaster @ |
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944 |
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Van Langenhove, L.; Depaepe, T.; Vicca, S.; van den Berge, J.; Stahl, C.; Courtois, E.; Weedon, J.; Urbina, I.; Grau, O.; Asensio, D.; Peñuelas, J.; Boeckx, P.; Richter, A.; Van Der Straeten, D.; Janssens, I.A. |
| Title |
Regulation of nitrogen fixation from free-living organisms in soil and leaf litter of two tropical forests of the Guiana shield |
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Journal Article |
| Year |
2020 |
Publication |
Plant and Soil |
Abbreviated Journal |
Plant Soil |
| Volume |
450 |
Issue |
1-2 |
Pages |
93-110 |
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Free-living nitrogen fixation; French Guiana; Molybdenum; Nutrients; Phosphorus; Tropical forest; acetylene; leaf litter; molybdenum; nitrogen fixation; nutrient cycling; phosphorus; rainforest; reduction; soil biota; soil carbon; soil nitrogen; soil water; topographic effect; tropical forest; French Guiana |
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Background and aims: Biological fixation of atmospheric nitrogen (N2) is the main pathway for introducing N into unmanaged ecosystems. While recent estimates suggest that free-living N fixation (FLNF) accounts for the majority of N fixed in mature tropical forests, the controls governing this process are not completely understood. The aim of this study was to quantify FLNF rates and determine its drivers in two tropical pristine forests of French Guiana. Methods: We used the acetylene reduction assay to measure FLNF rates at two sites, in two seasons and along three topographical positions, and used regression analyses to identify which edaphic explanatory variables, including carbon (C), nitrogen (N), phosphorus (P) and molybdenum (Mo) content, pH, water and available N and P, explained most of the variation in FLNF rates. Results: Overall, FLNF rates were lower than measured in tropical systems elsewhere. In soils seasonal variability was small and FLNF rates differed among topographies at only one site. Water, P and pH explained 24% of the variation. In leaf litter, FLNF rates differed seasonally, without site or topographical differences. Water, C, N and P explained 46% of the observed variation. We found no regulatory role of Mo at our sites. Conclusions: Rates of FLNF were low in primary rainforest on poor soils on the Guiana shield. Water was the most important rate-regulating factor and FLNF increased with increasing P, but decreased with increasing N. Our results support the general assumption that N fixation in tropical lowland forests is limited by P availability. © 2019, The Author(s). |
| Address |
Department of Microbiology and Ecosystem Science, University of Vienna, Althanstr. 14, Vienna, 1090, Austria |
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Springer |
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| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
no |
| Call Number |
EcoFoG @ webmaster @ |
Serial |
971 |
| Permanent link to this record |
