The Forestier silvicultural systems trial: Alternatives to clearfelling

The Forestier silvicultural systems trial was established over the period 1987 to 1989 and was designed to evaluate a variety of silvicultural systems in wet eucalypt forests. Treatments tested included clearfelling and sowing, with and without burning; harvesting of small gaps (group selection) of approximately 100 m diameter, with and without burning; and partial logging, which involved thinning of the overstorey. Successful regeneration was achieved only in the coupes that were clearfelled, burnt and sown. Stocking levels were adequate in the partially logged treatments shortly after sowing but declined in subsequent years and the result was poor by age five. Regeneration in all other treatments was unsuccessful. The ultimate failure of the regeneration within the alternative treatments is attributed to the intense browsing pressure which is thought to have followed the harvesting. Partial logging resulted in a noticeable increase in the growth rate of the retained trees in those treatments where between three quarters and one half of the trees were removed. However, thinning also resulted in a major proliferation of epicormic shoot development on the boles of the retained stems. The results of this trial have been compromised by the lack of browsing monitoring and subsequent control. The trial has clearly demonstrated that monitoring of browsing damage to regeneration, and control of browsing animals where damage levels are unacceptable, is an essential part of native forest silviculture.