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Early browsing damage to seedlings may yield benefits later on



The larvae of the autumn gum moth can cause severe damage to eucalypt plantations.  Early browsing of seedlings by mammalian herbivores may reduce the risk of infestation by these insect pests.

Christina Borzak (PhD student, University of Tasmania) is looking at genetics, ontogeny and the ability of plants to compensate for damage caused by browsing.  Over the summer, Chrissy has been continually monitoring her two E. globulus recovery trials at Taranna and at the Univerisity of Tasmania (see Biobuzz 7 - Comparing strategies for surviving browsers). These trials investigate the regrowth response of two populations of E. globulus seedlings to mammalian damage.  The treatments include two levels of biomass removal and a repeated browse treatment.  Chrissy has also been writing up the results of her “Gladstone recovery study” that she presented at the ESA conference in Sydney in December last year (see related article in this issue of Biobuzz). 

­ The study assessed the recovery of plants in response to mammalian browsing damage at seedling stages.  The results showed that when mammalian browsing resulted in more than 75% defoliation, the survivorship, plant height and form at one year were adversely affected. The changes in plant architecture were shown to have flow-on effects to the subsequent autumn gum moth (Mnesampela privita; see image, left) community and damage by the white cockatoo (Cacatua galerita), with taller plants being more susceptible to damage.

Biobuzz issue eight, March 2009