Developmental and Structural Section
Zanne, Amy E. , Coomes, David A. , Westoby, Mark , Ackerly, David D. .
Variation in xylem anatomy: a global perspective.
CONSIDERABLE variation exists among species in their stem properties related to water supply. Differences in stem hydraulics are largely determined by xylem anatomy. In general, hydraulic conductivity (efficiency) is expected to increase with increasing conduit diameter and density, and hydraulic safety is expected to increase with wood density; however, relationships between hydraulic safety and efficiency are less clear. Disparate studies have quantified wood anatomical traits across thousands of species. In this work, we are using many of these studies to examine global patterns in trait relationships and tracing the phylogenetic history of these traits. We examined tradeoffs among anatomical traits related to hydraulics, focusing on the anchor traits of vascular conduit diameter and density, and wood density. We found that conduit diameter was negatively related to conduit and wood density but wood density was unrelated to conduit density. These results were found both with and without incorporating phylogenetic relationships, although the strength of the relationships differed. Xylem traits showed strong phylogenetic signal, suggesting related species generally share similar trait values. We also compared these traits to latitude of speciesí origin environment and found that conduit density and wood density increased and conduit diameter decreased from the equator to the poles. Taken together, these results suggest a tradeoff in conduit packing in stems and an increase in hydraulic safety, most likely in relation to freeze-thaw embolism, towards the poles.
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1 - Macquarie University, Department of Biological Sciences, North Ryde, New South Wales, 2109, Australia
2 - University of Cambridge, Department of Plant Sciences, Downing Site, Downing Street, Cambridge, California, CB2 3EA, England
3 - University of California, Berkeley, Department of Integrative Biology, 3060 Valley Life Sciences Bldg #3140, Berkeley, California, 94720, USA
Presentation Type: Oral Paper:Papers for Sections
Location: 312/Bell Memorial Union
Date: Monday, July 31st, 2006
Time: 1:30 PM