The induction of tannins is sometimes used to infer their importance in anti-herbivore defense. Damage to red oak leaves by L. dispar induces CT and HT synthesis, which was believed to cause
decreased performance and fitness of L. dispar.
However, in subsequent studies on red oak, HTs were artificially increased by 15% dry wt., but this did not affect the performance of L. dispar.
Therefore, it appears that the induction of tannins in this case is only part of a suite of defenses that would be necessary to increase tree resistance.