Tree defense measurements
We took several types of measurements to characterize defenses of all 48
trees periodically as described in Kolb et al. (2019). We
collected phloem from each tree at 1.5 m height to determine composition
and concentrations of mono- and sesquiterpenes. We sampled phloem once a
month from May to October 2014 and from May to September 2015. All trees
were sampled on the same day by taking two phloem samples (1.25 cm dia.)
from opposite sides of the tree. Samples were kept in -20 °C until
analysis. Detailed descriptions of extraction and chemical analysis were
reported in Kolb et al. (2019).