Treatment application
On July 25, 2018, four fourth stadium tussock moth caterpillars were placed in mesh bags onto all experimental trees in five mesocosms (different mesocosms than those used in Experiment 1). After two days, all caterpillars were removed and the defoliation was completed to a uniform 50% level using pinking shears. For the same period, empty mesh bags covered trees in another five mesocosms (previously unused). This second set of mesocosms was used as a control for testing how defoliation may influence recovery from drought stress. On July 27, all mesocosms were subjected to an extended drought stress treatment. Once all leaves from at least 12 of 16 trees had turned completely brown and the shoot tip meristems had died, the mesocosms were watered to soil saturation. Consequently, mesocosms containing undefoliated trees were re-watered 12-17 days after drought stress initiation, whereas mesocosms containing defoliated trees were re-watered 17-21 days after drought stress initiation. Starting with the initial re-watering date, mesocosms were kept watered for an additional 42 days. Subsequently, the experiment was terminated and all trees were harvested (see below). Because of flooding by an extreme rain event in the middle of the experiment, two mesocosms of the defoliation treatment had to be eliminated.