Presentation Title

Hydraulic Efficiency and Mechanical Strength in Shrub Stems

Start Date

November 2016

End Date

November 2016

Location

HUB 302-#48

Type of Presentation

Poster

Abstract

Malosma laurina, Laurel Sumac, and Salvia mellifera, black sage, are shrubs that grow in coastal sage scrub in Southern California. Southern California has a Mediterranean-type climate, experiencing summer drought. Recently, this region has been experiencing long-term drought in addition to the characteristic summer drought. Laurel sumac and black sage have different strategies for coping with drought. Laurel sumac is deeply rooted and evergreen, while black sage is more shallowly rooted and summer deciduous. Our primary research question was, do these different strategies involve different tradeoffs between hydraulic efficiency and mechanical strength? Efficient water transport is directly related to larger xylem vessels. However, these larger vessels may not be as strong as smaller xylem vessels. Therefore, stronger, denser wood should have lower hydraulic conductivity. We hypothesize that black sage because it avoids drought and is shallowly rooted, will have lower hydraulic efficiency, but stronger wood than laurel sumac. We measured modulus of elasticity, modulus of rupture, and hydraulic conductivity of stems collected from the Arroyo Pescadero Canyon trailhead. We expect that black sage will have a lower modulus of elasticity, a higher modulus of rupture, but will have a lower hydraulic conductivity when compared to Laurel Sumac.

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Nov 12th, 4:00 PM Nov 12th, 5:00 PM

Hydraulic Efficiency and Mechanical Strength in Shrub Stems

HUB 302-#48

Malosma laurina, Laurel Sumac, and Salvia mellifera, black sage, are shrubs that grow in coastal sage scrub in Southern California. Southern California has a Mediterranean-type climate, experiencing summer drought. Recently, this region has been experiencing long-term drought in addition to the characteristic summer drought. Laurel sumac and black sage have different strategies for coping with drought. Laurel sumac is deeply rooted and evergreen, while black sage is more shallowly rooted and summer deciduous. Our primary research question was, do these different strategies involve different tradeoffs between hydraulic efficiency and mechanical strength? Efficient water transport is directly related to larger xylem vessels. However, these larger vessels may not be as strong as smaller xylem vessels. Therefore, stronger, denser wood should have lower hydraulic conductivity. We hypothesize that black sage because it avoids drought and is shallowly rooted, will have lower hydraulic efficiency, but stronger wood than laurel sumac. We measured modulus of elasticity, modulus of rupture, and hydraulic conductivity of stems collected from the Arroyo Pescadero Canyon trailhead. We expect that black sage will have a lower modulus of elasticity, a higher modulus of rupture, but will have a lower hydraulic conductivity when compared to Laurel Sumac.