Journal Article

Hydraulic and carbohydrate changes in experimental drought-induced mortality of saplings in two conifer species

William R.L. Anderegg and Leander D.L. Anderegg

Edited by Ram Oren

in Tree Physiology

Volume 33, issue 3, pages 252-260
Published in print March 2013 | ISSN: 0829-318X
Published online March 2013 | e-ISSN: 1758-4469 | DOI: http://dx.doi.org/10.1093/treephys/tpt016
Hydraulic and carbohydrate changes in experimental drought-induced mortality of saplings in two conifer species

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Global patterns of drought-induced forest die-off indicate that many forests may be sensitive to climate-driven mortality, but the lack of understanding of how trees and saplings die during drought hinders the projections of die-off, demographic bottlenecks and ecosystem trajectories. In this study, we performed a severe controlled drought experiment on saplings of Pinus edulis Engelm. and Juniperus osteosperma (Torr.) Little, two species that both experienced die-off in a recent ‘climate change-type’ drought. We examined the roles of carbohydrate and hydraulic changes in multiple tissues as the saplings died. We found that saplings of both species exhibited large degrees of loss of hydraulic conductivity prior to death. Neither species exhibited significant changes in carbohydrate concentrations in any tissue during the relatively short and severe imposed drought. Native hydraulic conductivity successfully predicted the degree of canopy mortality in both species, highlighting the importance of drought characteristics and tree attributes in influencing physiological pathways to mortality. The relationships elucidated here, as well as the differences between our results and previous findings in adult trees, can help inform mortality mechanisms in climate–vegetation models, especially for young trees, and to understand species response to severe drought across ontogeny.

Keywords: climate change; ecosystem trajectory; forest mortality; hydraulic conductivity; non-structural carbohydrates; plant physiology; vegetation model

Journal Article.  5592 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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