Regulation of Nitrogen Fixation from Free-Living Organisms in Soil and Leaf Litter of two tropical forests of the Guiana shield
Van Langenhove, Leandro (Universiteit Antwerpen. Departement Biologie)
Depaepe, Thomas (Ghent University)
Vicca, Sara (Universiteit Antwerpen. Departement Biologie)
Berge, Joke Van den (Universiteit Antwerpen. Departement Biologie)
Stahl, Clément (Université des Antilles. AgroParisTech)
Courtois, Elodie A. (Universiteit Antwerpen. Departement Biologie)
Weedon, J. T (Vrije Universiteit Amsterdam. Department of Ecological Science)
Urbina Barreto, Ifigenia (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Grau Fernández, Oriol (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Asensio, Dolores (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Peñuelas, Josep (Centre de Recerca Ecològica i d'Aplicacions Forestals)
Boeckx, Pascal (University of Ghent. Isotope Biosciencie Laboratory)
Richter, Andreas (Universität Wien. Department of Microbiology and Ecosystem Science)
Van Der Straeten, Dominique (Universiteit Gent)
Janssens, Ivan (University of Antwerp. Department of Biology)

Data:	2019
Resum:	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. 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. 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. 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.
Ajuts:	European Commission 610028
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Matèria:	Free-living nitrogen fixation ; Tropical forest ; French Guiana ; Nutrients ; Phosphorus ; Molybdenum
Publicat a:	Plant and soil, Vol. 450, Issue 1-2 (May 2020) , p. 93-110, ISSN 1573-5036

DOI: 10.1007/s11104-019-04012-1
PMID: 32624623

Postprint 41 p, 1.2 MB

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