Leaf damage does not affect leaf loss or chlorophyll content in the New Zealand pepper tree, kawakawa (Macropiper excelsum)

Abstract

Kawakawa (Macropiper excelsum) is an understorey, forest tree which sustains conspicuous and substantial herbivory from the larvae of a geometrid moth, Cleora scriptaria. This study examined the relationship between leaf abscission and the amount of damage a leaf had sustained. In the field, kawakawa trees showed no increase in the rate of leaf shedding in response to experimental damage by C. scriptaria larvae or to artificial damage produced by a hole punch, even when 90% of the leaf area was removed. The tree did not compensate for a loss in leaf area by increasing the chlorophyll content of damaged leaves. Although herbivore damage is conspicuous and appears detrimental, the tree’s leaf phenology does not appear to be affected. It is concluded that this plant species has evolved to tolerate frequent and severe feeding damage to its leaves.