Given the relatively slow reproduction rate of the tree and the ease with which insects appear to adapt to new circumstances, you would think there's more than enough time for insects to evolve the ability to eat every last green thing on the planet. But they don't. Most likely, both of these are true to some extent. We don't have that problem in nature. Even those insects well-adapted to various plants rarely defoliate them.
Scientists know that plants respond actively to their environment.
Plants form symbiotic relationships with beneficial fungi, acclimate themselves to low temperatures, detoxify air pollutants or tolerate them, manufacture antimicrobial chemicals, and brace themselves against a steady wind. But how these mechanisms work cannot be explained within any one field of biology. They're cloning genes from maize, switching on plant defenses with airborne signals, visualizing membrane activity during root growth with jellyfish proteins that glow, studying the behavioral responses of roots to varying soil conditions, using lasers to measure the electrical conductivity of plant cell membranes, and heading off to the jungle to watch plants respond to leafcutter ants. There aren't enough years in a career to do that. Students will receive the standard disciplinary training of whatever department they adopt as their 'home base,' with the same rigor as any other Ph.D. student.