Comparable canopy and soil free-living nitrogen fixation rates in a lowland tropical forest
Résumé
Biological nitrogen fixation (BNF) is a 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 15N2, 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 free-living 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.
Auteurs, date et publication :
Auteurs Leandro Van Langenhove , Thomas Depaepe , Lore T. Verryckt , Lucia Fuchslueger , Julian Donald , Celine Leroy , Sruthi M. Krishna Moorthy , Albert Gargallo-Garriga , M.D. Farnon Ellwood , Hans Verbeeck , Dominique Van Der Straeten , Josep Peñuelas , Ivan A. Janssens
Publication : Science of The Total Environment
Date : 2025
Volume : 754
Pages : 142202