1. Regulation of nitrogen fixation from free-living organisms in soil and leaf litter of two tropical forests of the Guiana shield
- Author
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Sara Vicca, Oriol Grau, Josep Peñuelas, Ifigenia Urbina, Thomas Depaepe, Dominique Van Der Straeten, Joke Van den Berge, Pascal Boeckx, Andreas Richter, James T. Weedon, Clément Stahl, Ivan A. Janssens, Elodie A. Courtois, Dolores Asensio, Leandro Van Langenhove, Centre of Excellence PLECO, Department of Biology, University of Antwerp (UA), Department of Biology Ghent, Laboratory of Functionnal Plant Biology, Ghent University, Ecologie des forêts de Guyane (UMR ECOFOG), Université des Antilles (UA)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)-AgroParisTech-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA), Laboratoire Ecologie, évolution, interactions des systèmes amazoniens (LEEISA), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS), Department of Ecological Science [Amsterdam], Vrije Universiteit [Brussels] (VUB), Global Ecology Unit (CREAF-CSIC-UAB), Centre de Recerca Ecològica i Aplicacions Forestals (CREAF), Unit CREAF-CSIC-UABB, CREAF, Centre de Recerca Ecologica i Applicacions Forestals, Consejo Superior de Investigaciones Científicas, Faculty of Bioscience Engineering, Isotope Bioscience Laboratory - ISOFY, Department of Microbiology and Ecosystem Science, University of Vienna, Department of Biology, Laboratory of Functionnal Plant Biology, Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-AgroParisTech-Université de Guyane (UG)-Centre National de la Recherche Scientifique (CNRS)-Université des Antilles (UA), Laboratoire Ecologie, Evolution, Interactions des Systèmes amazoniens (LEEISA), Centre National de la Recherche Scientifique (CNRS)-Université de Guyane (UG)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Vrije Universiteit Brussel (VUB), University of Vienna [Vienna], and Systems Ecology
- Subjects
0106 biological sciences ,forêt tropicale humide ,[SDV]Life Sciences [q-bio] ,Soil Science ,chemistry.chemical_element ,ACETYLENE-REDUCTION ,Plant Science ,Rainforest ,Biology ,01 natural sciences ,OXYGEN ,CARBON ,molybdenum ,tropical rain forests ,Nutrient ,Tropical forest ,free-living nitrogen fixation ,SYMBIOTIC DINITROGEN FIXATION ,nutrients ,Ecosystem ,SPATIAL VARIATION ,NUTRIENT AVAILABILITY ,phosphorus ,Molybdenum ,LIMITATION ,Phosphorus ,Biology and Life Sciences ,Regular Article ,Edaphic ,Nutrients ,RAIN-FOREST ,04 agricultural and veterinary sciences ,15. Life on land ,Plant litter ,French Guiana ,Agronomy ,chemistry ,fixation de l'azote ,Earth and Environmental Sciences ,Soil water ,040103 agronomy & agriculture ,Nitrogen fixation ,guyane française ,0401 agriculture, forestry, and fisheries ,Free-living nitrogen fixation ,010606 plant biology & botany - 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. Electronic supplementary material The online version of this article (10.1007/s11104-019-04012-1) contains supplementary material, which is available to authorized users.
- Published
- 2019
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