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).