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Does leaf shedding protect stems from cavitation during seasonal droughts? A test of the hydraulic fuse hypothesis
- Source :
- New Phytologist. 212:1007-1018
- Publication Year :
- 2016
- Publisher :
- Wiley, 2016.
-
Abstract
- During droughts, leaves are predicted to act as 'hydraulic fuses' by shedding when plants reach critically low water potential (Ψplant ), thereby slowing water loss, stabilizing Ψplant and protecting against cavitation-induced loss of stem hydraulic conductivity (Ks ). We tested these predictions among trees in seasonally dry tropical forests, where leaf shedding is common, yet variable, among species. We tracked leaf phenology, Ψplant and Ks in saplings of six tree species distributed across two forests. Species differed in their timing and extent of leaf shedding, yet converged in shedding leaves as they approached the Ψplant value associated with a 50% loss of Ks and at which their model-estimated maximum sustainable transpiration rate approached zero. However, after shedding all leaves, the Ψplant value of one species, Genipa americana, continued to decline, indicating that water loss continued after leaf shedding. Ks was highly variable among saplings within species and seasons, suggesting a minimal influence of seasonal drought on Ks . Hydraulic limits appear to drive diverse patterns of leaf shedding among tropical trees, supporting the hydraulic fuse hypothesis. However, leaf shedding is not universally effective at stabilizing Ψplant , suggesting that the main function of drought deciduousness may vary among species.
- Subjects :
- 0106 biological sciences
Time Factors
Physiology
Tropical trees
Plant Science
Models, Biological
010603 evolutionary biology
01 natural sciences
Trees
Abscission
Leaf phenology
Species Specificity
Hydraulic conductivity
Genipa americana
Transpiration
Plant Stems
biology
Ecology
Water
biology.organism_classification
Droughts
Plant Leaves
Water potential
Agronomy
Plant Stomata
Gases
Seasons
Tree species
010606 plant biology & botany
Subjects
Details
- ISSN :
- 14698137 and 0028646X
- Volume :
- 212
- Database :
- OpenAIRE
- Journal :
- New Phytologist
- Accession number :
- edsair.doi.dedup.....9ab016242ed36f99d2c92cb1cb0afa89