Leaf Natural15N Abundance and Total N Concentration as Potential Indicators of Plant N Nutrition in Legumes and Pioneer Species in a Rain Forest of French Guiana

• Published in: Oecologia Vol. 120; no. 2; pp. 171 - 182
• Main Authors: Roggy, J. C., Prévost, M. F., F. Gourbiere, H. Casabianca, Garbaye, J., Domenach, A. M.
• Format: Journal Article
• Language: English
• Published: Springer-Verlag 01-01-1999
• Subjects: Ecophysiology; Forest soils; Legumes; Pioneer species; Plants; Rain forests; Soil ecology; Trees; Tropical forests; Tropical rain forests; Tropical soils
• ISSN: 0029-8549; 1432-1939

The suitability of the natural15N abundance and of total N concentration of leaves as indicators of the type of plant N nutrition in a rain forest of French Guiana were tested. Leaf samples from primary legume species, non-legumes (pioneer species) and from the non-N₂-fixing species Dicorynia guianensis were analyzed. Both δ15N and total leaf N varied widely (-1 ≤ δ15N (‰) ≤ 7 and 1 ≤ leaf N(%) ≤ 3.2) suggesting possible distinctions between diazotrophic and non-fixing plants. The δ15N also revealed two statistically distinct groups of non-N₂-fixing species (δ15N = 5.14 ± 0.3 vs δ15N = 1.65 ± 0.17) related to the different ecological behaviors of these species in the successional processes. We conclude that the δ15N signature of plant leaves combined with their total N concentration may be relevant indicators for identifying functional groups within the community of non-N₂-fixing species, as well as for detecting diazotrophy. Despite the variability in the δ15N of the non-N₂-fixing species, N₂-fixing groups can still be identified, provided that plants are simultaneously classified taxonomically, by their leaf δ15N and total N concentration and by the presence or absence of nodules. The variability in the δ15N of the non-fixing species is discussed.