Effects of selective logging and regeneration treatments on mortality of retained trees in Tasmanian cool temperate rainforest

Summary

The mortality of major Tasmanian rainforest tree species, principally myrtle and sassafras, was recorded over 10–26 y on transects established to monitor myrtle wilt in trials of a range of selective logging and regeneration treatments and in an untreated control area. At the sites monitored for over 20 y, cumulative mortality of myrtle and sassafras ranged from 25% to 45% and 25% to 69% respectively. Following the logging and/or regeneration treatments, annual mortality of myrtle and sassafras was initially high at all sites, including the untreated control area. However, some 3–9 y after disturbance, mortality of myrtle had declined significantly and stabilised at background levels previously reported for undisturbed myrtle forests. Annual mortality of sassafras also declined but less than myrtle. Mortality rates at the control site followed a similar pattern to treated sites. The greatest increase in myrtle and sassafras deaths occurred in the area most heavily selectively logged. Areas lightly selectively logged and/or regeneration treatments had mortality increases similar to the control area. The importance of minimising tree damage to myrtle trees in any future operations to minimise spread of myrtle wilt is emphasised.

Keywords:

• logging effects
• regeneration
• mortality
• myrtle
• myrtle wilt
• sassafras
• Atherosperma moschatum
• Chalara australis
• Nothofagus cunninghamii
• Tasmania
• Australia