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Harvard Forest REU Symposium Abstract 2016

  • Title: Vulnerability to Cavitation in Xylem Across and Within Growth Rings in Four Hardwood Species
  • Author: Nathan A Stephansky (Bates College)
  • Abstract:

    Vulnerability to cavitation within xylem vessels is an important characteristic when predicting how a tree will respond to drought. The objective of this study was to determine how the vulnerability to cavitation differs in the xylem of growth rings ranging from current year through one and two year old rings, as well as within a growth ring from the earlywood to latewood. Measuring the air seeding pressure (ASP) in multiyear stem and trunk segments was used to quantify the vulnerability to cavitation in xylem of four hardwood species; red oak (Quercus rubra), white ash (Fraxinus americana), red maple (Acer rubrum), and American beech (Fagus grandifolia). Branch and trunk samples from sapling and mature trees for each species were collected at Harvard Forest, Petersham, MA and assessed for differences in ASP across species, growth ring, and earlywood versus latewood. Using ANOVA and Tukey’s HSD, there was no significant difference in ASP across growth rings for red oak, white ash, red maple, and American beech. Further investigation of the data suggested no difference in ASP within a growth ring from the earlywood to latewood. These results suggest that the vulnerability to cavitation is independent of xylem vessel age, whether it be across or within growth rings. If vulnerability to cavitation is independent of vessel age, then water transport within trees may not be as severely effected by drought as previous studies have indicated.

  • Research Category: Physiological Ecology, Population Dynamics, and Species Interactions