Growth of eucalypt regeneration established with and without slash burns in Tasmania

Summary

Early height growth of mixed eucalypt species regeneration established by clearfall, burn and sow treatments at four locations taking in a range of different forest sites in eastern and north-eastern Tasmania has been compared with that of natural regeneration on adjoining areas which were clearfelled at the same time but not burnt. The natural regeneration was of various origins but was generally still quite small at the time of the burn and sow treatments, which it pre-dated by up to 12 years. Height has been measured several times at each site during the period 2–10 years post-burn.

On two relatively wet sites (approximately 1250 mm and 1000 mm mean annual rainfall) the burn and sow treatments produced significantly faster early height growth than the unburnt treatments, but on the two drier sites (approximately 850 mm and 800 mm mean annual rainfall) growth rates did not differ significantly between treatments. On the drier sites the unburnt treatment allowed vigorous coppice shoots to establish an initial height advantage which has so far been maintained.

These early results suggest that, on productivity grounds, the case for slash burning is not so strong in Tasmania's drier, more open, lower quality forests as in the wetter, higher quality forests. Nevertheless, in the drier forests slash burns are still used more often than not, mainly to facilitate future fire protection.