Impact of nutrient additions on free-living nitrogen fixation in litter and soil of two French-Guianese lowland ropical forests
In tropical forests, free-living Biological nitrogen (N) fixation (BNF) in soil and littertends to decrease when substrate N concentrations increase, whereas increasing phosphorus (P) andmolybdenum (Mo) soil and litter concentrations have been shown to stimulate free-living BNF rates. Yet,very few s...
| Autores: | , , , , , , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Universitat Autònoma de Barcelona |
| Repositorio: | Dipòsit Digital de Documents de la UAB |
| Idioma: | inglés |
| OAI Identifier: | oai:ddd.uab.cat:299969 |
| Acceso en línea: | https://ddd.uab.cat/record/299969 https://dx.doi.org/urn:doi:10.1029/2020JG006023 |
| Access Level: | acceso abierto |
| Palabra clave: | Phosphorus Molybdenum Feld fertilization Cross-site comparison Acetylene reduction assay 15N2 calibration |
| Sumario: | In tropical forests, free-living Biological nitrogen (N) fixation (BNF) in soil and littertends to decrease when substrate N concentrations increase, whereas increasing phosphorus (P) andmolybdenum (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 fertilizationexperiment, which would teach us which of these elements constrain or limit BNF activities. At twodistinct forest sites in French Guiana, we performed a 3-year in situ nutrient addition study to explorethe 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 inthe lab, while Mo alone yielded no changes. Soil BNF increased with P and P+Mo additions in only one ofthe field sites, while in the other site soil BNF increased with Mo and P+Mo additions. We concluded thatincreased substrate N concentrations suppress BNF. Moreover, both P and Mo have the potential to limitfree-living BNF in these tropical forests, but the balance between P versus Mo limitation is determined bysite-specific characteristics of nutrient supply and demand. |
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