title: Complementary N Uptake Strategies between Tree Species in Tropical Rainforest.
abstract: Within tree communities, the differential use of soil N mineral resources, a key factor in ecosystem functioning, may reflect functional complementarity, a major mechanism that could explain species coexistence in tropical rainforests. Eperua falcata and Dicorynia guianensis, two abundant species cooccurring in rainforests of French Guiana, were chosen as representative of two functional groups with complementary N uptake strategies (contrasting leaf δ (15)N signatures related to the δ (15)N of their soil N source, NO3 (-) or NH4 (+)). The objectives were to investigate if these strategies occurred under contrasted soil N resources in sites with distinct geological substrates representative of the coastal rainforests. Results showed that species displayed contrasting leaf δ (15)N signatures on both substrates, confirming their complementary N uptake strategy. Consequently, their leaf (15)N can be used to trace the presence of inorganic N-forms in soils (NH4 (+) and NO3 (-)) and thus to indicate the capacity of soils to provide each of these two N sources to the plant community.
authors.affiliation: INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou Cedex, French Guiana.
authors.forename: J C
authors.initials: JC
authors.lastname: Roggy
authors.affiliation: INRA, UMR Ecologie des Forêts de Guyane, Campus Agronomique, BP 709, 97387 Kourou Cedex, French Guiana.
authors.forename: H
authors.initials: H
authors.lastname: Schimann
authors.affiliation: UMR Botanique et Bioinformatique de l'Architecture des Plantes (AMAP), TA A51/ PS2, 34398 Montpellier Cedex 5, France.
authors.forename: D
authors.initials: D
authors.lastname: Sabatier
authors.affiliation: UMR Botanique et Bioinformatique de l'Architecture des Plantes (AMAP), TA A51/ PS2, 34398 Montpellier Cedex 5, France.
authors.forename: J F
authors.initials: JF
authors.lastname: Molino
authors.affiliation: UR Dynamique des Forets Naturelles, TA C-37/D, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France.
authors.forename: V
authors.initials: V
authors.lastname: Freycon
authors.affiliation: Solicaz, c/o Guyane Technopole, 16 bis rue du 14 Juillet, 97 300 Cayenne, French Guiana.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Domenach