Vulnerability and hydraulic segmentations at the stem-leaf transition: coordination across Neotropical trees
Sébastien Levionnois1,2, Camille Ziegler1,3, Steven Jansen4
1UMR EcoFoG, AgroParisTech, CIRAD, CNRS, INRAE, Université des Antilles, Université de Guyane, Kourou, 97310, France.
The New Phytologist
|June 5, 2020
Summary
Tropical trees exhibit hydraulic segmentation, a mechanism where stem and leaf xylem function differently to resist embolism. This segmentation varies among species, impacting drought resistance strategies.
Area of Science:
- Plant Physiology
- Ecology
- Forest Science
Background:
- Hydraulic segmentation and vulnerability segmentation are key plant water transport mechanisms.
- These mechanisms theoretically favor leaves experiencing embolism to protect stems.
Purpose of the Study:
- To quantify hydraulic segmentation across 21 tropical rainforest tree species.
- To assess the coordination between hydraulic and vulnerability segmentation in tropical trees.
Main Methods:
- Anatomical approach to quantify theoretical leaf-specific conductivity.
- Flow-centrifugation technique for stem xylem embolism resistance.
- Optical visualization method for leaf xylem embolism resistance.
Main Results:
- Hydraulic segmentation was pervasive across species, but with significant variability.
- Eight species displayed positive vulnerability segmentation (leaves less resistant than stems).
- The degree of vulnerability segmentation correlated positively with hydraulic segmentation.
Conclusions:
- Segmented species effectively decouple leaf and stem xylem hydraulics.
- Further research is needed to integrate leaf-stem transition at the whole-plant level for drought resistance.
- Understanding these mechanisms is crucial for predicting forest responses to drought.
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