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Author 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. doi  openurl
  Title Extreme rainfall events alter the trophic structure in bromeliad tanks across the Neotropics Type Journal Article
  Year 2020 Publication (up) Nature Communications Abbreviated Journal Nat. Commun.  
  Volume 11 Issue 3215 Pages  
  Keywords 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  
  Abstract 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).  
  Address Institute of Biological Sciences, Universidade Federal do Pará, Belém, PA, Brazil  
  Corporate Author Thesis  
  Publisher Nature Research Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 20411723 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 944  
Permanent link to this record
 

 
Author Esquivel-Muelbert, A.; Phillips, O.L.; Brienen, R.J.W.; Fauset, S.; Sullivan, M.J.P.; Baker, T.R.; Chao, K.-J.; Feldpausch, T.R.; Gloor, E.; Higuchi, N.; Houwing-Duistermaat, J.; Lloyd, J.; Liu, H.; Malhi, Y.; Marimon, B.; Marimon Junior, B.H.; Monteagudo-Mendoza, A.; Poorter, L.; Silveira, M.; Torre, E.V.; Dávila, E.A.; del Aguila Pasquel, J.; Almeida, E.; Loayza, P.A.; Andrade, A.; Aragão, L.E.O.C.; Araujo-Murakami, A.; Arets, E.; Arroyo, L.; Aymard C, G.A.; Baisie, M.; Baraloto, C.; Camargo, P.B.; Barroso, J.; Blanc, L.; Bonal, D.; Bongers, F.; Boot, R.; Brown, F.; Burban, B.; Camargo, J.L.; Castro, W.; Moscoso, V.C.; Chave, J.; Comiskey, J.; Valverde, F.C.; da Costa, A.L.; Cardozo, N.D.; Di Fiore, A.; Dourdain, A.; Erwin, T.; Llampazo, G.F.; Vieira, I.C.G.; Herrera, R.; Honorio Coronado, E.; Huamantupa-Chuquimaco, I.; Jimenez-Rojas, E.; Killeen, T.; Laurance, S.; Laurance, W.; Levesley, A.; Lewis, S.L.; Ladvocat, K.L.L.M.; Lopez-Gonzalez, G.; Lovejoy, T.; Meir, P.; Mendoza, C.; Morandi, P.; Neill, D.; Nogueira Lima, A.J.; Vargas, P.N.; de Oliveira, E.A.; Camacho, N.P.; Pardo, G.; Peacock, J.; Peña-Claros, M.; Peñuela-Mora, M.C.; Pickavance, G.; Pipoly, J.; Pitman, N.; Prieto, A.; Pugh, T.A.M.; Quesada, C.; Ramirez-Angulo, H.; de Almeida Reis, S.M.; Rejou-Machain, M.; Correa, Z.R.; Bayona, L.R.; Rudas, A.; Salomão, R.; Serrano, J.; Espejo, J.S.; Silva, N.; Singh, J.; Stahl, C.; Stropp, J.; Swamy, V.; Talbot, J.; ter Steege, H.; Terborgh, J.; Thomas, R.; Toledo, M.; Torres-Lezama, A.; Gamarra, L.V.; van der Heijden, G.; van der Meer, P.; van der Hout, P.; Martinez, R.V.; Vieira, S.A.; Cayo, J.V.; Vos, V.; Zagt, R.; Zuidema, P.; Galbraith, D. doi  openurl
  Title Tree mode of death and mortality risk factors across Amazon forests Type Journal Article
  Year 2020 Publication (up) Nature Communications Abbreviated Journal Nat. Commun.  
  Volume 11 Issue 5515 Pages  
  Keywords bioclimatology; carbon sink; ecological modeling; growth; holistic approach; mortality; mortality risk; risk factor; survival; trade-off; tropical forest; article; climate; controlled study; forest; growth rate; human; mortality rate; mortality risk; survival; biological model; biomass; Brazil; carbon sequestration; ecology; ecosystem; environmental monitoring; growth, development and aging; proportional hazards model; risk factor; tree; tropic climate; Amazonia; carbon dioxide; Biomass; Brazil; Carbon Dioxide; Carbon Sequestration; Ecology; Ecosystem; Environmental Monitoring; Forests; Models, Biological; Proportional Hazards Models; Risk Factors; Trees; Tropical Climate  
  Abstract The carbon sink capacity of tropical forests is substantially affected by tree mortality. However, the main drivers of tropical tree death remain largely unknown. Here we present a pan-Amazonian assessment of how and why trees die, analysing over 120,000 trees representing > 3800 species from 189 long-term RAINFOR forest plots. While tree mortality rates vary greatly Amazon-wide, on average trees are as likely to die standing as they are broken or uprooted—modes of death with different ecological consequences. Species-level growth rate is the single most important predictor of tree death in Amazonia, with faster-growing species being at higher risk. Within species, however, the slowest-growing trees are at greatest risk while the effect of tree size varies across the basin. In the driest Amazonian region species-level bioclimatic distributional patterns also predict the risk of death, suggesting that these forests are experiencing climatic conditions beyond their adaptative limits. These results provide not only a holistic pan-Amazonian picture of tree death but large-scale evidence for the overarching importance of the growth–survival trade-off in driving tropical tree mortality. © 2020, The Author(s).  
  Address Tropenbos International, Wageningen, Netherlands  
  Corporate Author Thesis  
  Publisher Nature Research Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 20411723 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 945  
Permanent link to this record
 

 
Author Thomas, H.J.D.; Bjorkman, A.D.; Myers-Smith, I.H.; Elmendorf, S.C.; Kattge, J.; Diaz, S.; Vellend, M.; Blok, D.; Cornelissen, J.H.C.; Forbes, B.C.; Henry, G.H.R.; Hollister, R.D.; Normand, S.; Prevéy, J.S.; Rixen, C.; Schaepman-Strub, G.; Wilmking, M.; Wipf, S.; Cornwell, W.K.; Beck, P.S.A.; Georges, D.; Goetz, S.J.; Guay, K.C.; Rüger, N.; Soudzilovskaia, N.A.; Spasojevic, M.J.; Alatalo, J.M.; Alexander, H.D.; Anadon-Rosell, A.; Angers-Blondin, S.; te Beest, M.; Berner, L.T.; Björk, R.G.; Buchwal, A.; Buras, A.; Carbognani, M.; Christie, K.S.; Collier, L.S.; Cooper, E.J.; Elberling, B.; Eskelinen, A.; Frei, E.R.; Grau, O.; Grogan, P.; Hallinger, M.; Heijmans, M.M.P.D.; Hermanutz, L.; Hudson, J.M.G.; Johnstone, J.F.; Hülber, K.; Iturrate-Garcia, M.; Iversen, C.M.; Jaroszynska, F.; Kaarlejarvi, E.; Kulonen, A.; Lamarque, L.J.; Lantz, T.C.; Lévesque, E.; Little, C.J.; Michelsen, A.; Milbau, A.; Nabe-Nielsen, J.; Nielsen, S.S.; Ninot, J.M.; Oberbauer, S.F.; Olofsson, J.; Onipchenko, V.G.; Petraglia, A.; Rumpf, S.B.; Shetti, R.; Speed, J.D.M.; Suding, K.N.; Tape, K.D.; Tomaselli, M.; Trant, A.J.; Treier, U.A.; Tremblay, M.; Venn, S.E.; Vowles, T.; Weijers, S.; Wookey, P.A.; Zamin, T.J.; Bahn, M.; Blonder, B.; van Bodegom, P.M.; Bond-Lamberty, B.; Campetella, G.; Cerabolini, B.E.L.; Chapin, F.S., III; Craine, J.M.; Dainese, M.; Green, W.A.; Jansen, S.; Kleyer, M.; Manning, P.; Niinemets, Ü.; Onoda, Y.; Ozinga, W.A.; Peñuelas, J.; Poschlod, P.; Reich, P.B.; Sandel, B.; Schamp, B.S.; Sheremetiev, S.N.; de Vries, F.T. doi  openurl
  Title Global plant trait relationships extend to the climatic extremes of the tundra biome Type Journal Article
  Year 2020 Publication (up) Nature Communications Abbreviated Journal Nat. Commun.  
  Volume 11 Issue 1351 Pages  
  Keywords biome; climate change; extreme event; global change; growth; interspecific interaction; plant community; tundra; article; plant community; prediction; tundra; warming; classification; climate; ecosystem; genetics; plant; plant development; Climate; Ecosystem; Plant Development; Plants; Tundra  
  Abstract The majority of variation in six traits critical to the growth, survival and reproduction of plant species is thought to be organised along just two dimensions, corresponding to strategies of plant size and resource acquisition. However, it is unknown whether global plant trait relationships extend to climatic extremes, and if these interspecific relationships are confounded by trait variation within species. We test whether trait relationships extend to the cold extremes of life on Earth using the largest database of tundra plant traits yet compiled. We show that tundra plants demonstrate remarkably similar resource economic traits, but not size traits, compared to global distributions, and exhibit the same two dimensions of trait variation. Three quarters of trait variation occurs among species, mirroring global estimates of interspecific trait variation. Plant trait relationships are thus generalizable to the edge of global trait-space, informing prediction of plant community change in a warming world. © 2020, Crown.  
  Address Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Postbus 94240, Amsterdam, 1090 GE, Netherlands  
  Corporate Author Thesis  
  Publisher Nature Research Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 20411723 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 947  
Permanent link to this record
 

 
Author Levionnois, S.; Ziegler, C.; Jansen, S.; Calvet, E.; Coste, S.; Stahl, C.; Salmon, C.; Delzon, S.; Guichard, C.; Heuret, P. doi  openurl
  Title Vulnerability and hydraulic segmentations at the stem–leaf transition: coordination across Neotropical trees Type Journal Article
  Year 2020 Publication (up) New Phytologist Abbreviated Journal New Phytol.  
  Volume 228 Issue 2 Pages 512-524  
  Keywords drought-induced embolism resistance; hydraulic segmentation; leaf-specific conductivity; stem–leaf transition; tropical trees; vulnerability segmentation; air bubble; hydraulic conductivity; leaf; Neotropical Region; rainforest; tropical forest; vulnerability; xylem  
  Abstract Hydraulic segmentation at the stem–leaf transition predicts higher hydraulic resistance in leaves than in stems. Vulnerability segmentation, however, predicts lower embolism resistance in leaves. Both mechanisms should theoretically favour runaway embolism in leaves to preserve expensive organs such as stems, and should be tested for any potential coordination. We investigated the theoretical leaf-specific conductivity based on an anatomical approach to quantify the degree of hydraulic segmentation across 21 tropical rainforest tree species. Xylem resistance to embolism in stems (flow-centrifugation technique) and leaves (optical visualization method) was quantified to assess vulnerability segmentation. We found a pervasive hydraulic segmentation across species, but with a strong variability in the degree of segmentation. Despite a clear continuum in the degree of vulnerability segmentation, eight species showed a positive vulnerability segmentation (leaves less resistant to embolism than stems), whereas the remaining species studied exhibited a negative or no vulnerability segmentation. The degree of vulnerability segmentation was positively related to the degree of hydraulic segmentation, such that segmented species promote both mechanisms to hydraulically decouple leaf xylem from stem xylem. To what extent hydraulic and vulnerability segmentation determine drought resistance requires further integration of the leaf–stem transition at the whole-plant level, including both xylem and outer xylem tissue. © 2020 The Authors. New Phytologist © 2020 New Phytologist Trust  
  Address Univ. Bordeaux, INRAE, BIOGECO, Pessac, F-33615, France  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0028646x (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 952  
Permanent link to this record
 

 
Author Fortunel, C.; Stahl, C.; Heuret, P.; Nicolini, E.; Baraloto, C. doi  openurl
  Title Disentangling the effects of environment and ontogeny on tree functional dimensions for congeneric species in tropical forests Type Journal Article
  Year 2020 Publication (up) New Phytologist Abbreviated Journal New Phytol.  
  Volume 226 Issue 2 Pages 385-395  
  Keywords chemistry; developmental stage; habitats; Micropholis; morphology; physiology; plant traits; seasons; developmental stage; ecosystem function; forest ecosystem; habitat selection; habitat structure; nutrient availability; ontogeny; physiological response; soil water; taxonomy; tropical forest; Amazonia  
  Abstract Soil water and nutrient availability are key drivers of tree species distribution and forest ecosystem functioning, with strong species differences in water and nutrient use. Despite growing evidence for intraspecific trait differences, it remains unclear under which circumstances the effects of environmental gradients trump those of ontogeny and taxonomy on important functional dimensions related to resource use, particularly in tropical forests. Here, we explore how physiological, chemical, and morphological traits related to resource use vary between life stages in four species within the genus Micropholis that is widespread in lowland Amazonia. Specifically, we evaluate how environment, developmental stage, and taxonomy contribute to single-trait variation and multidimensional functional strategies. We find that environment, developmental stage, and taxonomy differentially contribute to functional dimensions. Habitats and seasons shape physiological and chemical traits related to water and nutrient use, whereas developmental stage and taxonomic identity impact morphological traits –especially those related to the leaf economics spectrum. Our findings suggest that combining environment, ontogeny, and taxonomy allows for a better understanding of important functional dimensions in tropical trees and highlights the need for integrating tree physiological and chemical traits with classically used morphological traits to improve predictions of tropical forests’ responses to environmental change. © 2019 The Authors New Phytologist © 2019 New Phytologist Trust  
  Address Department of Biological Sciences, Florida International University, Miami, FL 33133, United States  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0028646x (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 977  
Permanent link to this record
 

 
Author Schmitt, S.; Hérault, B.; Ducouret, É.; Baranger, A.; Tysklind, N.; Heuertz, M.; Marcon, É.; Cazal, S.O.; Derroire, G. doi  openurl
  Title Topography consistently drives intra- and inter-specific leaf trait variation within tree species complexes in a Neotropical forest Type Journal Article
  Year 2020 Publication (up) 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  
  Abstract 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  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 00301299 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 950  
Permanent link to this record
 

 
Author Shepard, W.D.; Clavier, S.; Cerdan, A. doi  openurl
  Title A generic key to the known larval elmidae (Insecta: Coleoptera) of French Guiana Type Journal Article
  Year 2020 Publication (up) Papeis Avulsos de Zoologia Abbreviated Journal Pap. Avulsos Zool.  
  Volume 60 Issue Special Pages e202060  
  Keywords Biodiversity; Identification; Immatures; Neotropical; Survey  
  Abstract An identification key is provided for 21 larval types of Elmidae (riffle beetles) known to occur in French Guiana. Not all elmid genera known to occur in French Guiana are known in the larval stage. Nor are all the known larval types assigned to known elmid genera. © 2020, Universidade de Sao Paulo. All rights reserved.  
  Address CNRS, UMR EcoFog (AgroParisTech, CIRAD, INRA, Université des Antilles, Université de Guyane), Kourou Cedex, France  
  Corporate Author Thesis  
  Publisher Universidade de Sao Paulo Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 00311049 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 980  
Permanent link to this record
 

 
Author Svensk, M.; Coste, S.; Gérard, B.; Gril, E.; Julien, F.; Maillard, P.; Stahl, C.; Leroy, C. doi  openurl
  Title Drought effects on resource partition and conservation among leaf ontogenetic stages in epiphytic tank bromeliads Type Journal Article
  Year 2020 Publication (up) Physiologia Plantarum Abbreviated Journal Physiol. Plant.  
  Volume 170 Issue 4 Pages 488-507  
  Keywords chlorophyll; nitrogen; water; Bromeliaceae; drought; metabolism; photosynthesis; plant leaf; Bromeliaceae; Chlorophyll; Droughts; Nitrogen; Photosynthesis; Plant Leaves; Water  
  Abstract Studying the response to drought stress of keystone epiphytes such as tank bromeliads is essential to better understand their resistance capacity to future climate change. The objective was to test whether there is any variation in the carbon, water and nutrient status among different leaf ontogenetic stages in a bromeliad rosette subjected to a gradient of drought stress. We used a semi-controlled experiment consisting in a gradient of water shortage in Aechmea aquilega and Lutheria splendens. For each bromeliad and drought treatment, three leaves were collected based on their position in the rosette and several functional traits related to water and nutrient status, and carbon metabolism were measured. We found that water status traits (relative water content, leaf succulence, osmotic and midday water potentials) and carbon metabolism traits (carbon assimilation, maximum quantum yield of photosystem II, chlorophyll and starch contents) decreased with increasing drought stress, while leaf soluble sugars and carbon, nitrogen and phosphorus contents remained unchanged. The different leaf ontogenetic stages showed only marginal variations when subjected to a gradient of drought. Resources were not reallocated between different leaf ontogenetic stages but we found a reallocation of soluble sugars from leaf starch reserves to the root system. Both species were capable of metabolic and physiological adjustments in response to drought. Overall, this study advances our understanding of the resistance of bromeliads faced with increasing drought stress and paves the way for in-depth reflection on their strategies to cope with water shortage. © 2020 Scandinavian Plant Physiology Society  
  Address Laboratoire Ecologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse, 31062, France  
  Corporate Author Thesis  
  Publisher Blackwell Publishing Ltd Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 00319317 (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes PDF trop gros voir la documentaliste – merci Approved no  
  Call Number EcoFoG @ webmaster @ Serial 943  
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Author 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. doi  openurl
  Title Regulation of nitrogen fixation from free-living organisms in soil and leaf litter of two tropical forests of the Guiana shield Type Journal Article
  Year 2020 Publication (up) Plant and Soil Abbreviated Journal Plant Soil  
  Volume 450 Issue 1-2 Pages 93-110  
  Keywords 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  
  Abstract 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  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0032079x (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 971  
Permanent link to this record
 

 
Author Urbina, I.; Grau, O.; Sardans, J.; Ninot, J.M.; Peñuelas, J. doi  openurl
  Title Encroachment of shrubs into subalpine grasslands in the Pyrenees changes the plant-soil stoichiometry spectrum Type Journal Article
  Year 2020 Publication (up) 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  
  Abstract 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.  
  Address Biodiversity Research Institute (IRBio) and Department of Evolutionary Biology, Ecology and Environmental Sciences, University of Barcelona, Barcelona, Catalonia, Spain  
  Corporate Author Thesis  
  Publisher Springer Place of Publication Editor  
  Language Summary Language Original Title  
  Series Editor Series Title Abbreviated Series Title  
  Series Volume Series Issue Edition  
  ISSN 0032079x (Issn) ISBN Medium  
  Area Expedition Conference  
  Notes Approved no  
  Call Number EcoFoG @ webmaster @ Serial 983  
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