title: Interactions among nitrogen fixation and soil phosphorus acquisition strategies in lowland tropical rain forests.
abstract: Paradoxically, symbiotic dinitrogen (N2 ) fixers are abundant in nitrogen (N)-rich, phosphorus (P)-poor lowland tropical rain forests. One hypothesis to explain this pattern states that N2 fixers have an advantage in acquiring soil P by producing more N-rich enzymes (phosphatases) that mineralise organic P than non-N2 fixers. We assessed soil and root phosphatase activity between fixers and non-fixers in two lowland tropical rain forest sites, but also addressed the hypothesis that arbuscular mycorrhizal (AM) colonisation (another P acquisition strategy) is greater on fixers than non-fixers. Root phosphatase activity and AM colonisation were higher for fixers than non-fixers, and strong correlations between AM colonisation and N2 fixation at both sites suggest that the N-P interactions mediated by fixers may generally apply across tropical forests. We suggest that phosphatase enzymes and AM fungi enhance the capacity of N2 fixers to acquire soil P, thus contributing to their high abundance in tropical forests.
authors: Department of Ecosystem and Conservation Sciences, University of Montana, Missoula, MT, 59812, USA.
authors: Megan K
authors: MK
authors: Nasto
authors: Silvia
authors: S
authors: Alvarez-Clare
authors: Ylva
authors: Y
authors: Lekberg
authors: Benjamin W
authors: BW
authors: Sullivan
authors: Alan R
authors: AR
authors: Townsend
authors: Cory C
authors: CC
authors: Cleveland
mesh_terms: D003364:Costa Rica; D065928:Forests; D038821:Mycorrhizae / Q000502:physiology*; D009586:Nitrogen Fixation; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism*; D018517:Plant Roots / Q000201:enzymology* / Q000382:microbiology; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry*; D014329:Tropical Climate
chemical_list: D012987:Soil; D010758:Phosphorus; D010744:Phosphoric Monoester Hydrolases
keywords: Arbuscular mycorrhizal fungi; nutrient acquisition strategies; phosphatase enzymes; tropical forest