PT Journal
AU Van Langenhove, L
   Depaepe, T
   Verryckt, LT
   Fuchslueger, L
   Donald, J
   Celine, L
   Krishna Moorthy, SM
   Gargallo-Garriga, A
   Farnon Ellwood, MD
   Verbeeck, H
   Van Der Straeten, D
   Penuelas, J
   Janssens, IA
TI Comparable canapy and soil free living nitrogen fixation rates in e lowland tropical forest
SO Science of the total environment
PY 2021
VL 754
DI 10.1016/j.scitotenv.2020.142202
LA Anglais
DE Biodiversité; Systématique; phylogénie; taxonomie; Ecologie; Environnement; Ecosystèmes; Biologie végétale; Botanique
AB 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.
ER