%0 Journal Article
%T Impact of Nutrient Additions on Free-Living Nitrogen Fixation in Litter and Soil of Two French-Guianese Lowland Tropical Forests
%A Van Langenhove, Leandro
%A Depaepe, Thomas
%A Verryckt, Lore T.
%A Vallicrosa, Helena
%A Fuchslueger, Lucia
%A Lugli, Laynara F.
%A Bréchet, Laëtitia M.
%A Ogaya, Roma
%A Llusia, Joan
%A Urbina, Ifigenia
%A Gargallo-Garriga, Albert
%A Grau, Oriol
%A Richter, Andreas
%A Penuelas, Josep
%A Van Der Straeten, Dominique
%A August Janssens, Ivan A.
%J JGR Biogeosciences
%D 2021
%V 126
%N 7
%I American Geophysical Union
%F VanLangenhove_etal2021
%O exported from refbase (http://php.ecofog.gf/refbase/show.php?record=1040), last updated on Wed, 20 Jul 2022 13:24:02 -0300
%X In tropical forests, free-living Biological nitrogen (N) fixation (BNF) in soil and litter tends to decrease when substrate N concentrations increase, whereas increasing phosphorus (P) and molybdenum (Mo) soil and litter concentrations have been shown to stimulate free-living BNF rates. Yet, very few studies explored the effects of adding N, P, and Mo together in a single large-scale fertilization experiment, which would teach us which of these elements constrain or limit BNF activities. At two distinct forest sites in French Guiana, we performed a 3-year in situ nutrient addition study to explore the effects of N, P, and Mo additions on leaf litter and soil BNF. Additionally, we conducted a short-term laboratory study with the same nutrient addition treatments (+N, +N+P, +P, +Mo, and +P+Mo). We found that N additions alone suppressed litter free-living BNF in the field, but not in the short-term laboratory study, while litter free-living BNF remained unchanged in response to N+P additions. Additionally, we found that P and P+Mo additions stimulated BNF in leaf litter, both in the field and in the lab, while Mo alone yielded no changes. Soil BNF increased with P and P+Mo additions in only one of the field sites, while in the other site soil BNF increased with Mo and P+Mo additions. We concluded that increased substrate N concentrations suppress BNF. Moreover, both P and Mo have the potential to limit free-living BNF in these tropical forests, but the balance between P versus Mo limitation is determined by site-specific characteristics of nutrient supply and demand.
%U http://dx.doi.org/10.1029/2020JG006023
%P e2020JG006023