Liana and tree below-ground water competition—evidence for water resource partitioning during the dry season

De Deurwaerder Hannes, Hervé-Fernández Pedro, Stahl Clément, Burban Benoit, Petronelli Pascal, Hoffman Bruce, Bonal Damien, Boeckx Pascal, Verbeeck Hans. 2018. Liana and tree below-ground water competition—evidence for water resource partitioning during the dry season. Tree Physiology, 38 (7) : 1071-1083.

https://doi.org/10.1093/treephys/tpy002

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Quartile : Q1, Sujet : FORESTRY

Résumé : To date, reasons for the increase in liana abundance and biomass in the Neotropics are still unclear. One proposed hypothesis suggests that lianas, in comparison with trees, are more adaptable to drought conditions. Moreover, previous studies have assumed that lianas have a deeper root system, which provides access to deeper soil layers, thereby making them less susceptible to drought stress. The dual stable water isotope approach (δ18O and δ2H) enables below-ground vegetation competition for water to be studied. Based on the occurrence of a natural gradient in soil water isotopic signatures, with enriched signatures in shallow soil relative to deep soil, the origin of vegetation water sources can be derived. Our study was performed on canopy trees and lianas reaching canopy level in tropical forests of French Guiana. Our results show liana xylem water isotopic signatures to be enriched in heavy isotopes in comparison with those from trees, indicating differences in water source depths and a more superficial root activity for lianas during the dry season. This enables them to efficiently capture dry season precipitation. Our study does not support the liana deep root water extraction hypothesis. Additionally, we provide new insights into water competition between tropical canopy lianas and trees. Results suggest that this competition is mitigated during the dry season due to water resource partitioning.

Mots-clés Agrovoc : forêt, besoin en eau, saison sèche, cycle hydrologique

Mots-clés géographiques Agrovoc : Guyane française, France

Mots-clés libres : Lianas, Soil water competition, Stable water isotopes, Tropical forest, Water resource partitioning

Classification Agris : F40 - Écologie végétale
K01 - Foresterie - Considérations générales
P10 - Ressources en eau et leur gestion

Champ stratégique Cirad : Axe 6 (2014-2018) - Sociétés, natures et territoires

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