Nitrogen cycling in the tropical rain forest of French Guiana: comparison of two sites with contrasting soil types using delta 15N - Université Claude Bernard Lyon 1 Accéder directement au contenu
Article Dans Une Revue Journal of Tropical Ecology Année : 1999

Nitrogen cycling in the tropical rain forest of French Guiana: comparison of two sites with contrasting soil types using delta 15N

Résumé

The natural 15N abundance method for estimating symbiotic biological N2-fixation was tested on legume trees from two rain forests on contrasting soils (oxisols and spodosols) in French Guiana. When possible, the significance of N2-fixing species in the plant community was evaluated in terms of density, biomass and contribution of N2-fixation to the building up of the total nitrogen mass in the leaves. Of the two sites, the rain forest on spodosols was the less favourable for application of the [delta]15N method: the available soil nitrogen was isotopically similar to fixed-N2. Hence, the results showed that a reliable estimate of N2-fixation could not be obtained. A substantial contribution of fixed-N2 to the nitrogen nutrition of legumes was found on oxisols, with an average value of 54 % Ndfa (Nitrogen derived from the atmosphere). The contribution of the N2-fixing legumes to the biomass of the stand was estimated to be 2 t ha[minus sign]1 for the leaf biomass and 136 t ha[minus sign]1 for the total above-ground plant biomass. With 7.5 % of trees in the stand able to fix N2 (462 out of 6156), N2-fixation was estimated to be 7 kg ha[minus sign]1 y[minus sign]1. These results are the first use of the [delta]15N method to estimate nitrogen input by N2-fixing legumes to a natural rain forest. The inter-site variability observed in the [delta]15N of the non-fixing plants suggested different nitrogen-cycling processes in the two soils. The [delta]15N of the non-N2-fixing plants could be related to the soil nitrogen availability and be used as an indicator of efficient or non-efficient nitrogen-cycling rain forests. The spatial variability of the [delta]15N in the plant-available soil nitrogen pool and the nitrogen balance in tropical rain forests are discussed.
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Dates et versions

hal-01032201 , version 1 (22-07-2014)

Identifiants

Citer

Jean-Christophe Roggy, Marie-Françoise Prévost, Jean Garbaye, Anne-Marie Domenach. Nitrogen cycling in the tropical rain forest of French Guiana: comparison of two sites with contrasting soil types using delta 15N. Journal of Tropical Ecology, 1999, 15 (1), pp.1-22. ⟨10.1017/S0266467499000644⟩. ⟨hal-01032201⟩
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