Defoliation, tree growth and storage of C and N

Severe herbivory is presumed to reduce tree growth through resulting limitations of nitrogen and carbon. Piper et al. examine the effects of herbivory of Nothofagus pumilio (lenga beech) by caterpillars of Ormiscodes amphimone and find that whilst completely defoliated trees do not die, they show reduced growth for at least 2 years. However, the concentrations of nitrogen and non-structural carbohydrate (NSC) in woody tissues are not reduced, and defoliated trees have higher concentrations of leaf polyphenols and branch NSC, indicating that growth is not limited by C or N. Instead, increased allocation of C to storage or limitation of resources other than C and N appears to be responsible for the decrease in growth.