Did belowground N transfer in mixed plantations of Acacia mangium and Eucalyptus meet the Stress Gradient Hypothesis?

De Oliveira Ivanka Rosada, Ribeiro Paula Ranieri, Bordron Bruno, Vicente Ferraz Alexandre, Gonçalves José Leonardo M., Amaral Guerrini I., Robin Agnès, Bouillet Jean-Pierre. 2019. Did belowground N transfer in mixed plantations of Acacia mangium and Eucalyptus meet the Stress Gradient Hypothesis?. Pesquisa Florestal Brasileira, 39, n.spéc., Résumé : 280. IUFRO World Congress 2019 "Forest Research and Cooperation for Sustainable Development". 25, Curitiba, Brésil, 29 Septembre 2019/5 Octobre 2019.

https://pfb.cnpf.embrapa.br/pfb/index.php/pfb/article/view/2043/

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Url - éditeur : https://pfb.cnpf.embrapa.br/pfb/index.php/pfb/article/view/2043/900

Résumé : Belowground interactions in mixed forest plantations remain poorly understood as that of short-tenn nitrogen (N) transfer from N-fixing trees to non-N-fixing trees (Non-NFT) depending on nutrient availability. We investigated in this facilitation process met the Stress Gradient Hypothesis. which predicts that under stressful environmental conditions competition decreases and facilitation increases. A 15N pulse-labelling study was conducted in a five-year-old mixture of 50% Eucalyptus grandis x E. urophylla and 50% Acacia mangium with the hypothesis of higher transfer from acacia when no fertilization was applied. A complete randomized block design was set up with three replicates of fertilized and non-fertilized mixture. In each treatment of each block, a labeled solution of potassium nitrate (98 atom% 15N-N03) was injected into the stem of an Acacia tree with the same basal area as the average of the stand. The x (15N) was monitored over two months in each labeled acacia and four neighboring eucalypts. For both species, young leaves and tine roots were sampled at 7.14 and 30 days after injection. After 60 days. the x (15N) was determined in the wood, bark, branches, total foliage and fine roots of the 6 labeled acacias and 12 eucalypts trees The preliminary results showed that complete absorption of the labeled solution occurred between 28 and 60 days after labeling depending on Acacia trees and treatments. The dynamics in the proportion of Eucalyptus N derived from transfer will give insights into how this process may promote N nutrition of non-NFTs growing in unfertile tropical soils.

Mots-clés Agrovoc : Eucalyptus grandis, Eucalyptus urophylla, Acacia mangium, forêt mélangée, plantation forestière, Fixation de l'azote, stress abiotique, fertilité du sol, sol tropical

Classification Agris : K10 - Production forestière
F61 - Physiologie végétale - Nutrition
P35 - Fertilité du sol
F04 - Fertilisation

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

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