Recent Topics Posters
Aranda, Ismael , Kleinsasser, Ian , Stanfield, Ryan , Bergman, Brett A. , Ewers, Madeleine M. , Bobich, Edward , Ewers, Frank W. .
Mechanical strength and water relations parameters are correlated in leaves: Two species, two growth habits, two strategies in responding to Mediterranean conditions .
Tensile strength and tensile elasticity were measured jointly with water relations parameters such as pre-dawn and mid-day water potentials, wilting point, osmotic adjustment and modulus of elasticity in leaves of evergreen coast live oak, Quercus agrifolia and deciduous southern California black walnut, Juglans californica. These two trees were dominant on a north-facing slope in southern California where about half of the individuals were burned and resprouted following wildfire in 2008, and half the trees were unburned adults that did not endure the fire effects. The different morphological and physiological traits were measured on leaves at different ontogenetic states from flushing, staring in January 2009, and are being followed seasonally. It was found that as leaves matured there were increases in tensile strength, tensile elasticity and modulus of elasticity. The mechanical strength was observed along with decreases in specific leaf area, predawn and midday water potentials and wilting point. By late spring there were further increases in mechanical strength, tensile elasticity, and elastic modulus, and decreases in field water potentials, wilting point, indicating osmotic and mechanical adjustment, especially in oak. Oak had greater tensile strength, tensile elasticity and osmotic adjustment, and lower specific leaf area and lower field water potentials and wilting points than walnut. For both species, adults had greater leaf mechanical strength, leaf tensile elasticity and greater osmotic adjustment but lower specific leaf area, lower field water potentials and lower wilting points than the resprouts. Thus the strength properties were correlated with various water relations measurements, suggesting a linkage between mechanical and water relations properties of leaves, but also two very different patterns to face Mediterranean conditions by the two studied species.
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1 - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Centro de Investigación Forestal (CIFOR), Carretera de La Coruña km 7.5, Madrid, 28040, Spain
2 - California State Polytechnic University, Biological Sciences, 3801 West Temple Avenue, Pomona, CA, 91768, USA
3 - University of Michigan, Department of Chemistry, Ann Arbor, MI, USA
modulus of elasticity
coast live oak
California black walnut
Presentation Type: Recent Topics Poster
Location: Event Tent/Cliff Lodge
Date: Monday, July 27th, 2009
Time: 5:30 PM