Physical properties and monoterpene composition of xylem oleoresin along the bole of Pinus taeda in relation to southern pine beetle attack distribution

Abstract

Eight trees from each of four different age-classes (5–15, 16–25, 26–35, and 36–45 years) were sampled at 10 equally spaced heights along the bole for xylem oleoresin physical properties (initial flow rate, total flow, and viscosity) and monoterpene composition. Trees in the 36- to 45-year-old age-class had a significantly faster initial resin flow rate and greater total flow than trees from the other age-classes. No significant differences in initial flow rate, total flow, and relative viscosity were observed between sample heights. Unexpected differences in monoterpene composition occurred between age-classes. α-Pinene decreased and β-pinene increased with increasing height for all trees in all age-classes. Camphene decreased with increasing height in the 5- to 15-year-old age-class and β-phellandrene increased with increasing height in the age-classes of 16–25 and 26–35 years. No obvious xylem oleoresin properties at the different heights were observed that might suggest a favorable condition for southern pine beetle attack.