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Fukami, T.; Nakajima, M.; Fortunel, C.; Fine, P.V.A.; Baraloto, C.; Russo, S.E.; Peay, K.G. |
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Geographical variation in community divergence: insights from tropical forest monodominance by ectomycorrhizal trees |
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Journal Article |
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2017 |
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American Naturalist |
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American Naturalist |
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190 |
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S105-S122 |
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Community assembly; Mycorrhizae; Plant traits; Plant-soil feedback; Priority effects; Species pools |
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Convergence occurs in both species traits and community structure, but how convergence at the two scales influences each other remains unclear. To address this question, we focus on tropical forest monodominance, in which a single, often ectomycorrhizal (EM) tree species occasionally dominates forest stands within a landscape otherwise characterized by diverse communities of arbuscular mycorrhizal (AM) trees. Such monodominance is a striking potential example of community divergence resulting in alternative stable states. However, it is observed only in some tropical regions. A diverse suite of AM and EM trees locally codominate forest stands elsewhere. We develop a hypothesis to explain this geographical difference using a simulation model of plant community assembly. Simulation results suggest that in a region with a few EM species (e.g., South America), EM trees experience strong selection for convergent traits that match the abiotic conditions of the environment. Consequently, EM species successfully compete against other species to form monodominant stands via positive plant-soil feedbacks. By contrast, in a region with many EM species (e.g., Southeast Asia), species maintain divergent traits because of complex plant-soil feedbacks, with no species having traits that enablemonodominance. An analysis of plant trait data from Borneo and Peruvian Amazon was inconclusive. Overall, this work highlights the utility of geographical comparison in understanding the relationship between trait convergence and community convergence. © 2017 by The University of Chicago. |
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School of Biological Sciences, University of Nebraska, Lincoln, NE, United States |
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EcoFoG @ webmaster @ |
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761 |
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Dejean, A.; Petitclerc, F.; Compin, A.; Azémar, F.; Corbara, B.; Delabie, J.H.C.; Leroy, C. |
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Hollow internodes permit a neotropical understory plant to shelter multiple mutualistic ant species, obtaining protection and nutrient provisioning (myrmecotrophy) |
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Journal Article |
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2017 |
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American Naturalist |
Abbreviated Journal |
American Naturalist |
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190 |
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5 |
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E124-E131 |
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Ant-plant relationships; Biotic protection; Mutualism; Myrmecotrophy; Stable isotopes; Tachia guianensis |
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The Neotropical understory plant Tachia guianensis (Gentianaceae)- known to shelter the colonies of several ant species in its hollow trunks and branches-does not provide them with food rewards (e.g., extrafloral nectar). We tested whether these ants are opportunistic nesters or whether mutualistic relationships exist as for myrmecophytes or plants sheltering ant colonies in specialized hollow structures in exchange for protection from enemies and/or nutrient provisioning (myrmecotrophy). We noted 37 ant species sheltering inside T. guianensis internodes, three of them accounting for 43.5% of the cases. They protect their host plants from leaf-cutting ant defoliation and termite damage because individuals devoid of associated ants suffered significantly more attacks. Using the stable isotope 15N, we experimentally showed that the tested ant species furnish their host plants with nutrients. Therefore, a mutualism exists. However, because it is associated with numerous ant species, T. guianensis can be considered a nonspecialized myrmecophyte. © 2017 by The University of Chicago. |
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Institut de Recherche pour le Développement, UMR botAnique et Modélisation de l’Archtecture des Plantes et des Végétations, Cirad, CNRS, INRA, Université de Montpellier, Boulevard de la Lironde, TA A-51/PS2, Montpellier cedex 5, Brazil |
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Export Date: 2 November 2017 |
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EcoFoG @ webmaster @ |
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768 |
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Haettenschwiler, S.; Coq, S.; Barantal, S.; Handa, I.T. |
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Leaf traits and decomposition in tropical rainforests: revisiting some commonly held views and towards a new hypothesis |
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2011 |
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New Phytologist |
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New Phytol. |
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189 |
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4 |
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950-965 |
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energy starvation; French Guiana; litter quality; mycorrhizas; nutrient cycling; nutrient limitation; phosphorus; soil fauna |
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Proper estimates of decomposition are essential for tropical forests, given their key role in the global carbon (C) cycle. However, the current paradigm for litter decomposition is insufficient to account for recent observations and may limit model predictions for highly diverse tropical ecosystems. In light of recent findings from a nutrient-poor Amazonian rainforest, we revisit the commonly held views that: litter traits are a mere legacy of live leaf traits; nitrogen (N) and lignin are the key litter traits controlling decomposition; and favourable climatic conditions result in rapid decomposition in tropical forests. Substantial interspecific variation in litter phosphorus (P) was found to be unrelated to variation in green leaves. Litter nutrients explained no variation in decomposition, which instead was controlled primarily by nonlignin litter C compounds at low concentrations with important soil fauna effects. Despite near-optimal climatic conditions, tropical litter decomposition proceeded more slowly than in a climatically less favourable temperate forest. We suggest that slow decomposition in the studied rainforest results from a syndrome of poor litter C quality beyond a simple lignin control, enforcing energy starvation of decomposers. We hypothesize that the litter trait syndrome in nutrient-poor tropical rainforests may have evolved to increase plant access to limiting nutrients via mycorrhizal associations. |
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[Haettenschwiler, Stephan; Coq, Sylvain; Barantal, Sandra; Handa, Ira Tanya] CNRS, CEFE, F-34293 Montpellier 5, France, Email: stephan.hattenschwiler@cefe.cnrs.fr |
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Wiley-Blackwell |
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0028-646x |
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ISI:000286940500009 |
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EcoFoG @ webmaster @ |
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296 |
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Fichaux, M.; Béchade, B.; Donald, J.; Weyna, A.; Delabie, J.H.C.; Murienne, J.; Baraloto, C.; Orivel, J. |
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Habitats shape taxonomic and functional composition of Neotropical ant assemblages |
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2019 |
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Oecologia |
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Oecologia |
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189 |
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2 |
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501-513 |
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Formicidae; Functional diversity; Habitat filtering; Rainforest; Traits; Formicidae |
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Determining assembly rules of co-occurring species persists as a fundamental goal in community ecology. At local scales, the relative importance of environmental filtering vs. competitive exclusion remains a subject of debate. In this study, we assessed the relative importance of habitat filtering and competition in structuring understory ant communities in tropical forests of French Guiana. Leaf-litter ants were collected using pitfall and Winkler traps across swamp, slope and plateau forests near Saül, French Guiana. We used a combination of univariate and multivariate analyses to evaluate trait response of ants to habitat characteristics. Null model analyses were used to investigate the effects of habitat filtering and competitive interactions on community assembly at the scale of assemblages and sampling points, respectively. Swamp forests presented a much lower taxonomic and functional richness compared to slope and plateau forests. Furthermore, marked differences in taxonomic and functional composition were observed between swamp forests and slope or plateau forests. We found weak evidence for competitive exclusion based on null models. Nevertheless, the contrasting trait composition observed between habitats revealed differences in the ecological attributes of the species in the different forest habitats. Our analyses suggest that competitive interactions may not play an important role in structuring leaf-litter ant assemblages locally. Rather, habitats are responsible for driving both taxonomic and functional composition of ant communities. |
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International Center for Tropical Botany, Department of Biological Sciences, Florida International University, Miami, FL 33199, United States |
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Springer Verlag |
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00298549 (Issn) |
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863 |
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Phillips, O.L.; van der Heijden, G.; Lewis, S.L.; Lopez-Gonzalez, G.; Aragao, L.E.O.C.; Lloyd, J.; Malhi, Y.; Monteagudo, A.; Almeida, S.; Davila, E.A.; Amaral, I.; Andelman, S.; Andrade, A.; Arroyo, L.; Aymard, G.; Baker, T.R.; Blanc, L.; Bonal, D.; de Oliveira, A.C.A.; Chao, K.J.; Cardozo, N.D.; da Costa, L.; Feldpausch, T.R.; Fisher, J.B.; Fyllas, N.M.; Freitas, M.A.; Galbraith, D.; Gloor, E.; Higuchi, N.; Honorio, E.; Jimenez, E.; Keeling, H.; Killeen, T.J.; Lovett, J.C.; Meir, P.; Mendoza, C.; Morel, A.; Vargas, P.N.; Patino, S.; Peh, K.S.H.; Cruz, A.P.; Prieto, A.; Quesada, C.A.; Ramirez, F.; Ramirez, H.; Rudas, A.; Salamao, R.; Schwarz, M.; Silva, J.; Silveira, M.; Slik, J.W.F.; Sonke, B.; Thomas, A.S.; Stropp, J.; Taplin, J.R.D.; Vasquez, R.; Vilanova, E. |
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Drought-mortality relationships for tropical forests |
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2010 |
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New Phytologist |
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New Phytol. |
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187 |
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3 |
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631-646 |
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Amazon; Borneo; drought; lags mortality; RAINFOR; trees; tropics |
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The rich ecology of tropical forests is intimately tied to their moisture status. Multi-site syntheses can provide a macro-scale view of these linkages and their susceptibility to changing climates. Here, we report pan-tropical and regional-scale analyses of tree vulnerability to drought. We assembled available data on tropical forest tree stem mortality before, during, and after recent drought events, from 119 monitoring plots in 10 countries concentrated in Amazonia and Borneo. In most sites, larger trees are disproportionately at risk. At least within Amazonia, low wood density trees are also at greater risk of drought-associated mortality, independent of size. For comparable drought intensities, trees in Borneo are more vulnerable than trees in the Amazon. There is some evidence for lagged impacts of drought, with mortality rates remaining elevated 2 yr after the meteorological event is over. These findings indicate that repeated droughts would shift the functional composition of tropical forests toward smaller, denser-wooded trees. At very high drought intensities, the linear relationship between tree mortality and moisture stress apparently breaks down, suggesting the existence of moisture stress thresholds beyond which some tropical forests would suffer catastrophic tree mortality. |
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[Phillips, Oliver L.; van der Heijden, Geertje; Lewis, Simon L.; Lopez-Gonzalez, Gabriela; Lloyd, Jon; Baker, Tim R.; Chao, Kuo-Jung; Feldpausch, Ted R.; Fyllas, Nikolaos M.; Gloor, Emanuel; Honorio, Euridice; Keeling, Helen; Quesada, Carlos A.; Schwarz, Michael] Univ Leeds, Sch Geog, Leeds LS2 9JT, W Yorkshire, England, Email: o.phillips@leeds.ac.uk |
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WILEY-BLACKWELL PUBLISHING, INC |
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ISI:000280122500028 |
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EcoFoG @ eric.marcon @ |
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50 |
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Dejean, A.; Céréghino, R.; Leponce, M.; Rossi, V.; Roux, O.; Compin, A.; Delabie, J.H.C.; Corbara, B. |
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The fire ant Solenopsis saevissima and habitat disturbance alter ant communities |
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2015 |
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Biological Conservation |
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Biological Conservation |
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187 |
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145-153 |
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Ant community; Fire ants; Invasive species; Species coexistence; Supercoloniality |
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The fire ant Solenopsis saevissima is a major pest frequent in human-disturbed areas of its native range where it forms 'supercolonies'. We determined that its natural habitat in French Guiana is likely the sporadically flooded riparian forest and aimed to evaluate this ant's impact on the abundance and diversity of other ants by comparing different habitats at two sites. We noted a significant decrease in ant species richness between the rainforest and human-disturbed habitats (but not between the former and the naturally disturbed riparian forest), and between extreme habitats and all others. The number of ant nests per surface unit (i.e., quadrats of equal surface area), a proxy of ant abundance, globally followed this pattern. S. saevissima was absent from pristine rainforest (as expected) and from extreme habitats, showing the limits of its adaptability, whereas some other native ants can develop in these habitats. Ant species richness was significantly lower in the presence of S. saevissima in the riparian forest, forest edges and meadows, illustrating that this ant species has a negative impact on the ant communities in addition to the impact of natural- and man-made disturbances. Only some ant species can develop in its presence, and certain of these can even thrive. Because it has been recorded in Africa, Guadeloupe and the Galápagos Islands, we concluded that, due to the increasing volume of global trade and forest destruction, S. saevissima could become a pantropical invasive species. © 2015 Elsevier Ltd. |
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Université Clermont Auvergne, Université Blaise Pascal (LMGE), Clermont-Ferrand, France |
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Export Date: 11 June 2015 |
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605 |
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Houel, E.; Nardella, F.; Jullian, V.; Valentin, A.; Vonthron-Sénécheau, C.; Villa, P.; Obrecht, A.; Kaiser, M.; Bourreau, E.; Odonne, G.; Fleury, M.; Bourdy, G.; Eparvier, V.; Deharo, E.; Stien, D. |
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Wayanin and guaijaverin, two active metabolites found in a Psidium acutangulum Mart. ex DC (syn. P. persoonii McVaugh) (Myrtaceae) antimalarial decoction from the Wayana Amerindians |
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Journal Article |
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2016 |
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Journal of Ethnopharmacology |
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Journal of Ethnopharmacology |
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187 |
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241-248 |
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Antimalarial; Cytokines; French guiana; Glycosylated flavonols; Psidium acutangulum; Traditional remedy |
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Ethnopharmacological relevance Psidium acutangulum Mart. ex DC is a small tree used by the Wayana Amerindians from the Upper-Maroni in French Guiana for the treatment of malaria. Aim of the study In a previous study, we highlighted the in vitro antiplasmodial, antioxidant and anti-inflammatory potential of the traditional decoction of P. acutangulum aerial parts. Our goal was then to investigate on the origin of the biological activity of the traditional remedy, and eventually characterize active constituents. Materials and methods Liquid-liquid extractions were performed on the decoction, and the antiplasmodial activity evaluated against chloroquine-resistant FcB1 ([3H]-hypoxanthine bioassay) and 7G8 (pLDH bioassay) P. falciparum strains, and on a chloroquine sensitive NF54 ([3H]-hypoxanthine bioassay) P. falciparum strain. The ethyl acetate fraction (D) was active and underwent bioguided fractionation. All the isolated compounds were tested on P. falciparum FcB1 strain. In vitro anti-inflammatory activity (IL-1β, IL-6, IL-8, TNFα) of the ethyl acetate fraction and of an anti-Plasmodium active compound, was concurrently assessed on LPS-stimulated human PBMC and NO secretion inhibition was measured on LPS stimulated RAW murine macrophages. Cytotoxicity of the fractions and pure compounds was measured on VERO cells, L6 mammalian cells, PBMCs, and RAW cells. Results Fractionation of the ethyl acetate soluble fraction (IC50 ranging from 3.4 to <1 μg/mL depending on the parasite strain) led to the isolation of six pure compounds: catechin and five glycosylated quercetin derivatives. These compounds have never been isolated from this plant species. Two of these compounds (wayanin and guaijaverin) were found to be moderately active against P. falciparum FcB1 in vitro (IC50 5.5 and 6.9 μM respectively). We proposed the name wayanin during public meetings organized in June 2015 in the Upper-Maroni villages, in homage to the medicinal knowledge of the Wayana population. At 50 μg/mL, the ethyl acetate fraction (D) significantly inhibited IL-1β secretion (-46%) and NO production (-21%), as previously observed for the decoction. The effects of D and guiajaverin (4) on the secretion of other cytokines or NO production were not significant. Conclusions The confirmed antiplasmodial activity of the ethyl acetate soluble fraction of the decoction and of the isolated compounds support the previous results obtained on the P. acutangulum decoction. The antiplasmodial activity might be due to a mixture of moderately active non-toxic flavonoids. The anti-inflammatory activities were less marked for ethyl acetate fraction (D) than for the decoction. © 2016 Elsevier Ireland Ltd. All rights reserved. |
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Sorbonne Universités, UPMC Univ Paris 06, CNRS, Laboratoire de Biodiversité et Biotechnologies Microbiennes (LBBM), Observatoire Océanologique, Banyuls/Mer, France |
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Export Date: 20 May 2016 |
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679 |
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Rodríguez Pérez, H.; Borrel, G.; Leroy, C.; Carrias, J.-F.; Corbara, B.; Srivastava, D.S.; Céréghino, R. |
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Simulated drought regimes reveal community resilience and hydrological thresholds for altered decomposition |
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2018 |
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Oecologia |
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187 |
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1 |
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267-279 |
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Future climate scenarios forecast a 10–50% decline in rainfall in Eastern Amazonia. Altered precipitation patterns may change important ecosystem functions like decomposition through either changes in physical and chemical processes or shifts in the activity and/or composition of species. We experimentally manipulated hydroperiods (length of wet:dry cycles) in a tank bromeliad ecosystem to examine impacts on leaf litter decomposition. Gross loss of litter mass over 112 days was greatest in continuously submersed litter, lowest in continuously dry litter, and intermediate over a range of hydroperiods ranging from eight cycles of 7 wet:7 dry days to one cycle of 56 wet:56 dry days. The resilience of litter mass loss to hydroperiod length is due to a shift from biologically assisted decomposition (mostly microbial) at short wet:dry hydroperiods to physicochemical release of dissolved organic matter at longer wet:dry hydroperiods. Biologically assisted decomposition was maximized at wet:dry hydroperiods falling within the range of ambient conditions (12–22 consecutive dry days) but then declined under prolonged wet:dry hydroperiods (28 and 56 dry days. Fungal:bacterial ratios showed a similar pattern as biologically assisted decomposition to hydroperiod length. Our results suggest that microbial communities confer functional resilience to altered hydroperiod in tank bromeliad ecosystems. We predict a substantial decrease in biological activity relevant to decomposition under climate scenarios that increase consecutive dry days by 1.6- to 3.2-fold in our study area, whereas decreased frequency of dry periods will tend to increase the physicochemical component of decomposition. |
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1432-1939 |
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EcoFoG @ webmaster @ Rodríguez Pérez2018 |
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Perrin, A.-S.; Fujisaki, K.; Petitjean, C.; Sarrazin, M.; Godet, M.; Garric, B.; Horth, J.-C.; Balbino, L.C.; Filho, A.S.; de Almeida Machado, P.L.O.; Brossard, M. |
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Conversion of forest to agriculture in Amazonia with the chop-and-mulch method: Does it improve the soil carbon stock? |
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2014 |
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Agriculture, Ecosystems and Environment |
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Agric. Ecosyst. Environ. |
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184 |
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101-114 |
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Annual crops; Brachiaria; Deforestation; Fire-free; French Guiana; No-tillage |
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Fire-free forest conversion with organic inputs as an alternative to slash-and-burn could improve agro-ecosystem sustainability. We assessed soil carbon mass changes in a sandy-clayey and well-drained soil in French Guiana after forest clearing by the chop-and-mulch method and crop establishment. At the experimental site of Combi, native forest was cut down in October 2008; woody biomass was chopped and incorporated into the top 20cm of soil. After about one year of legume and grass cover, three forms of land management were compared: grassland (Urochloa ruziziensis), maize/soybean crop rotation with disk tillage and in direct seeding without tillage. There were four replicates. We measured 14.16kgm-2 of carbon in 2mm-sieved soil down to 2m depth for the initial forest. Forest clearing did not induce significant soil compaction; neither did any specific agricultural practice. In converted soils, C stocks were measured in the 0-30cm layer after each crop for three years. Carbon mass changes for soil fractions <2mm (soil C stock) and >2mm (soil C pool) in the 0-5, 5-10, 10-20 and 20-30cm soil layers were assessed on an equivalent soil mass basis. One year and 1.5 years after deforestation, higher C stocks (+0.64 to 1.16kgCm-2yr-1) and C pools (+0.52 to 0.90kgCm-2yr-1) were measured in converted soils, compared to those of the forest into the top 30cm of soil. However, the masses of carbon in these converted soils declined later. The highest rates of carbon decrease were measured between 1.5 and 2 years after forest conversion in the <2mm soil fraction, from 0.46kgCm-2yr-1 (in grassland soils) to 0.71kgCm-2yr-1 (in cropland under no tillage). The carbon pool declined during the third year at rates of 0.41kgCm-2yr-1 (cropland under disk tillage) to 0.76kgCm-2yr-1 (grassland soils). Three years after forest conversion, C masses in the top 30cm of soils for grassland showed similar values than for forest. In comparison, the carbon stock in cropped soils managed under no tillage in direct seeding (without mulch) was significantly 17% and 16% lower than in forest and grassland soils, respectively. None of the studied agricultural practices succeeded in accumulating carbon from the chopped forest biomass. © 2013 Elsevier B.V. |
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EMBRAPA Arroz e Feijao, Cx Postal 179, CEP 75375-000 Santo Antonio de Goias, GO, Brazil |
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Export Date: 2 January 2014; Source: Scopus; Coden: Aeend; doi: 10.1016/j.agee.2013.11.009 |
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Martos, F.; Dulormne, M.; Pailler, T.; Bonfante, P.; Faccio, A.; Fournel, J.; Dubois, M.-P.; Selosse, M.-A. |
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Independent recruitment of saprotrophic fungi as mycorrhizal partners by tropical achlorophyllous orchids |
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2009 |
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New Phytologist |
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New Phytologist |
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184 |
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668-681 |
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Mycoheterotrophy; Mycorrhizas; Orchids; Rainforests; Saprotrophic fungi; Stable isotopes |
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Mycoheterotrophic orchids have adapted to shaded forest understory by shifting to achlorophylly and receiving carbon from their mycorrhizal fungi. In temperate forests, they associate in a highly specific way with fungi forming ectomycorrhizas on nearby trees, and exploiting tree photosynthates. However, many rainforests lack ectomycorrhizal fungi, and there is evidence that some tropical Asiatic species associate with saprotrophic fungi. To investigate this in different geographic and phylogenetic contexts, we identified the mycorrhizal fungi supporting two tropical mycoheterotrophic orchids from Mascarene (Indian Ocean) and Caribbean islands. We tested their possible carbon sources by measuring natural nitrogen (15N) and carbon (13C) abundances. Saprotrophic basidiomycetes were found: Gastrodia similis associates with a wood-decaying Resinicium (Hymenochaetales); Wullschlaegelia aphylla associates with both litter-decaying Gymnopus and Mycena species, whose rhizomorphs link orchid roots to leaf litter. The 15N and 13C abundances make plausible food chains from dead wood to G. similis and from dead leaves to W. aphylla. We propose that temperature and moisture in rainforests, but not in most temperate forests, may favour sufficient saprotrophic activity to support development of mycoheterotrophs. By enlarging the spectrum of mycorrhizal fungi and the level of specificity in mycoheterotrophic orchids, this study provides new insights on orchid and mycorrhizal biology in the tropics. © 2009 New Phytologist. |
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Dipartimento di Biologia Vegetale dell'Università, Istituto per la Protezione Delle Piante – CNR, Viale Mattioli 25, I-10125 Torino, Italy |
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Cited By :65; Export Date: 7 February 2017 |
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