Depth of soil water uptake by tropical rainforest trees during dry periods: Does tree dimension matter?

Stahl Clément, Hérault Bruno, Rossi Vivien, Burban Benoit, Bréchet Claude, Bonal Damien. 2013. Depth of soil water uptake by tropical rainforest trees during dry periods: Does tree dimension matter?. Oecologia, 173 (4) : 1191-1201.

https://doi.org/10.1007/s00442-013-2724-6

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Quartile : Q2, Sujet : ECOLOGY

Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Psychologie-éthologie-ergonomie

Résumé : Though the root biomass of tropical rainforest trees is concentrated in the upper soil layers, soil water uptake by deep roots has been shown to contribute to tree transpiration. A precise evaluation of the relationship between tree dimensions and depth of water uptake would be useful in tree-based modelling approaches designed to anticipate the response of tropical rainforest ecosystems to future changes in environmental conditions. We used an innovative dual-isotope labelling approach (deuterium in surface soil and oxygen at 120-cm depth) coupled with a modelling approach to investigate the role of tree dimensions in soil water uptake in a tropical rainforest exposed to seasonal drought. We studied 65 trees of varying diameter and height and with a wide range of predawn leaf water potential (?pd) values. We confirmed that about half of the studied trees relied on soil water below 100-cm depth during dry periods. ?pd was negatively correlated with depth of water extraction and can be taken as a rough proxy of this depth. Some trees showed considerable plasticity in their depth of water uptake, exhibiting an efficient adaptive strategy for water and nutrient resource acquisition. We did not find a strong relationship between tree dimensions and depth of water uptake. While tall trees preferentially extract water from layers below 100-cm depth, shorter trees show broad variations in mean depth of water uptake. This precludes the use of tree dimensions to parameterize functional models.

Mots-clés Agrovoc : forêt tropicale humide, racine, relation plante eau, deuterium, oxygène, croissance, absorption d'eau, profondeur, résistance à la sécheresse

Mots-clés géographiques Agrovoc : Afrique tropicale, Asie du Sud-Est, Amazonie

Classification Agris : K01 - Foresterie - Considérations générales
F62 - Physiologie végétale - Croissance et développement
F61 - Physiologie végétale - Nutrition
P33 - Chimie et physique du sol

Champ stratégique Cirad : Axe 6 (2005-2013) - Agriculture, environnement, nature et sociétés

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