Safety and streamlining of woody shoots in wind: an empirical study across 39 species in tropical Australia
Article first published online: 14 OCT 2011
© 2011 The Authors. New Phytologist © 2011 New Phytologist Trust
Volume 193, Issue 1, pages 137–149, January 2012
How to Cite
Butler, D. W., Gleason, S. M., Davidson, I., Onoda, Y. and Westoby, M. (2012), Safety and streamlining of woody shoots in wind: an empirical study across 39 species in tropical Australia. New Phytologist, 193: 137–149. doi: 10.1111/j.1469-8137.2011.03887.x
- Issue published online: 2 DEC 2011
- Article first published online: 14 OCT 2011
- Received: 27 April 2011, Accepted: 12 August 2011
- wood density
- •Wind is a key mechanical stress for woody plants, so how do shoot traits affect performance in wind?
- •We used a vehicle mounted apparatus to measure drag, streamlining and mechanical safety in 127 vertical lead-shoots, 1.2 m long, across 39 species in tropical Australia.
- •Shoot dimensions and stem tissue properties were closely coupled so that shoots with low stem specific gravity or larger projected area had thicker stems. Thicker stems provide larger second moment of area (I), which increased shoot safety and bending stiffness but impeded shoot reconfiguration in strong winds, including frontal area reduction. Nonetheless, increasing I also improved streamlining. Streamlining was unrelated to traits except I. Stem tissue material properties only had small effects. Higher modulus of rupture increased shoot safety and higher Young’s modulus impeded shoot reconfiguration.
- •We found no conflict between bending stiffness and streamlining for woody shoots. Stiffness might help streamlining by increasing damping and stability, thereby reducing flagging in wind. Tissue-level traits did influence shoot-level mechanical safety and behaviour, but shoot geometry was much more important. Variable shoot and stem traits, which all influenced shoot biomechanics, were integrated in shoots to yield a relatively narrow range of outcomes in wind.