Dieback of rural eucalypts: Tree phenology and damage caused by leaf‐feeding insects

Abstract

AbstractDuring three growing seasons, phenology and damage on leafy shoots of healthy eucalypts and others with dieback were monitored on pastoral properties in the Australian Capital Territory. Leaves from the dieback trees tended to be younger than those from nearby healthy trees. Leaves that were not lost prematurely lived for similar lengths of time on both dieback and healthy trees, but more leaves were initiated on the dieback trees. Dieback trees were also less active reproductively. During the study, chewing insects caused most of the damage on leaves, and there was usually more of this damage on leaves from the dieback trees. Young leaves accumulated damage at a much faster rate than older leaves, and this probably contributed to the relatively greater damage on the leaves from the dieback trees. However, the differences in the amount of damage on the leaves from healthy and dieback trees were not solely due to the differences in ages of the leaves. Generalized linear models which equalized the effects of the differences in leafing phenology produced adjusted estimates for damage to leaves that were still higher for dieback trees.