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Title
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Impact of nutrient additions on free-living nitrogen fixation in litter and soil of two French-Guianese lowland tropical forests
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Author
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Abstract
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| 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. |
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Language
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English
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Source (journal)
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Journal of geophysical research : biogeosciences / American Geophysical Union [Washington, D.C.] - Hoboken, N.J., 2013, currens
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Publication
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Hoboken, N.J.
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2021
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ISSN
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2169-8953
[print]
2169-8961
[online]
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DOI
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10.1029/2020JG006023
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Volume/pages
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126
:7
(2021)
, 15 p.
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Article Reference
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e2020JG006023
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ISI
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000677821700013
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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Full text (publisher's version - intranet only)
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