Graduation Date
Winter 2002
Document Type
Thesis
Program
Other
Program
Master of Arts Degree with a major in Biological Sciences
Committee Chair Name
Stephen C. Sillett
Committee Chair Affiliation
Cal Poly Humboldt Faculty or Staff
Second Committee Member Name
Michael A. Camann
Third Committee Member Name
Eric S. Jules
Fourth Committee Member Name
Dennis K. Walker
Keywords
x
Abstract
Recent research on whole-tree water relations has revealed interesting patterns of hydraulic variation in tall conifers. This work has been accompanied by an increasing attention to foliar anatomy and the role it plays in a tree's hydraulic functioning. In spite of broad interest in this topic, redwood, one of the potentially most interesting species, has been little studied. This thesis addresses our poor understanding of redwood by examining potential causes of foliar variation, testing the ability of foliage to directly absorb water, and quantifying vertical gradients in xylem pressure potential (psi x),stable carbon isotope ratio (delta 13C),light environment, foliar morphology, and leaf anatomy. On average, from the lowest to the uppermost foliage (generally 40m to 11 Om), leaf surface area to mass ratio (SA:M) decreased from 64.3 cm2/g to 20.5 cm 2/g, foliar delta 13C increased from -29.3 % to -25.5 %, and vascular bundle cross-sectional area increased from 0.012 mm2 to 0.023 mm2. Height and path length were the best predictors of foliar SA:M in a step-wise regression model that included wood volume, number of branch junctions, and light environment. Experimental increases in light environment induced a significant decrease in leaf SA:M and caused significant 13C enrichment relative to reduced light treatments. One hour of experimental misting with water relaxed psi xby 20%. There are three major conclusions of this study: (1) photosynthesis in tall redwoods is limited by stomata! conduction, (2) both foliar morphology and delta 13C are affected by light availability, and (3) redwoods are capable of direct foliar absorption of moisture.
Recommended Citation
Jennings, Gregory M., "Vertical Hydraulic Gradients and the Cause of Foliar Variation in Tall Redwood Trees (Sequoia Sempervirens)" (2002). Cal Poly Humboldt theses and projects. 2620.
https://digitalcommons.humboldt.edu/etd/2620