TY  - JOUR
AU  - Levionnois, Sébastien
AU  - Ziegler, Camille
AU  - Heuret, Patrick
AU  - Jansen, Steven
AU  - Stahl, Clément
AU  - Calvet, Emma
AU  - Goret, Jean-Yves
AU  - Bonal, Damien
AU  - Coste, Sabrina
PY  - 2021//
TI  - Is vulnerability segmentation at the leaf‑stem transition a drought resistance mechanism? A theoretical test with a trait‑based model for Neotropical canopy tree species
JO  - Annals of Forest Science
SP  - 78
EP  - 87
VL  - 78
IS  - 4
PB  - Springer Link
KW  - Neotropics
KW  - bark
KW  - canopy
KW  - capacitance
KW  - drought
KW  - drought tolerance
KW  - embolism
KW  - leaves
KW  - models
KW  - transpiration
KW  - trees
KW  - tropical rain forests
KW  - xylem
N2  - Leaf-stem vulnerability segmentation predicts lower xylem embolism resistance in leaves than stem. However, although it has been intensively investigated these past decades, the extent to which vulnerability segmentation promotes drought resistance is not well understood. Based on a trait-based model, this study theoretically supports that vulnerability segmentation enhances shoot desiccation time across 18 Neotropical tree species. CONTEXT: Leaf-stem vulnerability segmentation predicts lower xylem embolism resistance in leaves than stems thereby preserving expensive organs such as branches or the trunk. Although vulnerability segmentation has been intensively investigated these past decades to test its consistency across species, the extent to which vulnerability segmentation promotes drought resistance is not well understood. AIMS: We investigated the theoretical impact of the degree of vulnerability segmentation on shoot desiccation time estimated with a simple trait-based model. METHODS: We combined data from 18 tropical rainforest canopy tree species on embolism resistance of stem xylem (flow-centrifugation technique) and leaves (optical visualisation method). Measured water loss under minimum leaf and bark conductance, leaf and stem capacitance, and leaf-to-bark area ratio allowed us to calculate a theoretical shoot desiccation time (tcᵣᵢₜ). RESULTS: Large degrees of vulnerability segmentation strongly enhanced the theoretical shoot desiccation time, suggesting vulnerability segmentation to be an efficient drought resistance mechanism for half of the studied species. The difference between leaf and bark area, rather than the minimum leaf and bark conductance, determined the drastic reduction of total transpiration by segmentation during severe drought. CONCLUSION: Our study strongly suggests that vulnerability segmentation is an important drought resistance mechanism that should be better taken into account when investigating plant drought resistance and modelling vegetation. We discuss future directions for improving model assumptions with empirical measures, such as changes in total shoot transpiration after leaf xylem embolism.
UR  - http://dx.doi.org/10.1007/s13595-021-01094-9
N1  - exported from refbase (http://php.ecofog.gf/refbase/show.php?record=1034), last updated on Thu, 21 Jul 2022 09:06:04 -0300
ID  - Levionnois_etal2021
ER  -