Effects of Different Rates and Methods of Leaf Area Removal on Rain Forest Seedlings of Coachwood (Ceratopetalum apetalum)

Abstract

Different ways in which insect herbivores may consume the same proportions of leaf area were compared experimentally in their effects on a host plant. Part of the leaf tissue was removed from seedlings of Ceratopetalum apetalum, a native Australian rain forest tree, and growth recovery was monitored. Seedlings maintained in a controlled environment were subjected to one of five defoliation treatments: 25% of each leaf removed: 50% of each leaf removed; one of every four leaves removed; one of every two leaves removed; control. Growth was stimulated beyond the rate of the controls in both types of treatments with 25% removal of whole leaves or of leaf tissue; but was suppressed to a greater degree with 50% tissue removal. Seedlings with all leaves partially clipped recovered more successfully than those with some leaves completely removed, and the implications of this are discussed in relation to the behaviour of herbivores.