Variability in accumulation of proanthocyanidins (condensed tannins) in needles of Douglas-fir (Pseudotsuga menziesii) following long-term budworm defoliation.

Long-term defoliation by budworms was associated with higher levels of soluble proanthocyanidins in the current year needles of Douglas-fir trees. The proanthocyanidin contents of needles from defoliated Douglas-fir trees were considerably more variable than those levels of undefoliated ones. The increased mean and variability of proanthocyanidin levels following defoliation may have interesting ecological consequences for Douglas-fir and its defoliators.