Dry‐season decline in tree sapflux is correlated with leaf turgor loss point in a tropical rainforest. (21st August 2018)

• Record Type: Journal Article
• Authors: Maréchaux, Isabelle; Bonal, Damien; Bartlett, Megan K.; Burban, Benoît; Coste, Sabrina; Courtois, Elodie A.; Dulormne, Maguy; Goret, Jean‐Yves; Mira, Eléonore; Mirabel, Ariane; Sack, Lawren; Stahl, Clément; Chave, Jérôme
• Editors: Sala, Anna
• Is Part Of: Functional ecology. Volume 32:Number 10(2018)
• Page Start: 2285
• Page End: 2297
• Publication Date: 2018-08-21
• Subjects: drought tolerance -- hydraulic conductance -- sap flow -- sapflux density -- tropical trees -- turgor loss point -- water potential -- wilting point; Ecology -- Periodicals; 574.505
• DOI: 10.1111/1365-2435.13188
• Languages: English
• ISSNs: 0269-8463

Abstract

Abstract: Water availability is a key determinant of forest ecosystem function and tree species distributions. While droughts are increasing in frequency in many ecosystems, including in the tropics, plant responses to water supply vary with species and drought intensity and are therefore difficult to model. Based on physiological first principles, we hypothesized that trees with a lower turgor loss point ( π tlp ), that is, a more negative leaf water potential at wilting, would maintain water transport for longer into a dry season. We measured sapflux density of 22 mature trees of 10 species during a dry season in an Amazonian rainforest, quantified sapflux decline as soil water content decreased and tested its relationship to tree π tlp, size and leaf predawn and midday water potentials measured after the onset of the dry season. The measured trees varied strongly in the response of water use to the seasonal drought, with sapflux at the end of the dry season ranging from 37 to 117% (on average 83 ± 5 %) of that at the beginning of the dry season. The decline of water transport as soil dried was correlated with tree π tlp (Spearman's ρ ≥ 0.63), but not with tree size or predawn and midday water potentials. Thus, trees with more drought‐tolerant leaves better maintained water transport during the seasonal drought. Our study provides an explicit correlation between a trait, measurable at the leaf level, and whole‐plant performance under drying conditions. Physiological traits such as π tlp can be used to assess and model higher scale processes in response to drying conditions. A plain language summary is available for this article. Abstract : Plain Language Summary