Van Langenhove L. auteur aut IRD Depaepe T. auteur aut IRD Verryckt L. T. auteur aut IRD Fuchslueger L. auteur aut IRD Donald J. auteur aut IRD Leroy Céline auteur aut IRD Moorthy S. M. K. auteur aut IRD Gargallo-Garriga A. auteur aut IRD Ellwood M. D. F. auteur aut IRD Verbeeck H. auteur aut IRD Van der Straeten D. auteur aut IRD Penuelas J. auteur aut IRD Janssens I. A. auteur aut IRD text journalArticle eng text/pdf born digital access Biological nitrogen fixation (BNF) isa fundamental part of nitrogen cycling in tropical forests, yet little is known about the contribution made by free-living nitrogen fixers inhabiting the often-extensive forest canopy. We used the acetylene reduction assay, calibrated with N-15(2), to measure free-living BNF on forest canopy leaves, vascular epiphytes, bryophytes and canopy soil, as well as on the forest floor in leaf litter and soil. We used a combination of calculated and published component densities to upscale free-living BNF rates to the forest level. We found that bryophytes and leaves situated in the canopy in particular displayed high mass-based rates of freeliving BNF. Additionally, we calculated that nearly 2 kg of nitrogen enters the forest ecosystem through free-living BNF every year, 40% of which was fixed by the various canopy components. Our results reveal that in the studied tropical lowland forest a large part of the nitrogen input through free-living BNF stems from the canopy, but also that the total nitrogen inputs by free-living BNF are lower than previously thought and comparable to the inputs of reactive nitrogen by atmospheric deposition. specialized Canopy soil Epiphytes Leaves Litter Bryophytes N-15(2) Terrestrial LIDAR GUYANE FRANCAISE ZONE TROPICALE 082 084 074 754 142202 [ p.] 2021 0048-9697 https://www.documentation.ird.fr/hor/fdi:010080461 10.1016/j.scitotenv.2020.142202 0048-9697 [F B010080461] https://www.documentation.ird.fr/hor/fdi:010080461 https://www.documentation.ird.fr/intranet/publi/2021/01/010080461.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2021-02-08 2025-02-24 fdi:010080461 fre