Impact of fire regimes, logging and topography on hollows in fallen logs in eucalypt forest of south eastern Australia

Log hollows provide important habitat for a range of vertebrate fauna. Despite this, little is known about the impact fire regimes have on this resource, or the role topography may play in preserving hollows through the mitigation of fire intensity. This study examined the effect different combinations of fire frequency and topography have on (i) the number of hollow bearing logs and (ii) the presence and size of hollows within logs. The influence of wildfire severity and logging were also examined. Hollow availability (i.e. density of hollow bearing logs and hollow presence within logs) was greatest at sites burnt at ‘low’ frequency. The density of hollow logs was greater in gullies, though the effect of fire frequency did not vary with topographic position. Hollows showing signs of internal fire charring typically had a greater entrance width than unburnt hollows, which suggests fire plays an important role in creating large hollows. The number of hollow bearing logs increased with logging intensity, due to unmerchantable timber being left in situ. Wildfire severity had little effect on log hollows. The results indicate that frequent burning may reduce hollow availability, though it is likely that gullies will still retain a high density of hollow bearing logs irrespective of burning, and may play an important role in preserving connectivity of this resource across landscapes.

► Hollows (i.e. cavities) within logs provide important habitat for an array of fauna.
► We examined the effect of fire frequency, topography, logging intensity and fire severity on log hollows.
► Hollow availability was greater in areas burnt at low frequency and in gullies as opposed to ridges.
► The density of hollow logs increased with logging intensity, though subsequent declines in hollow log density are expected.
► Restricting anthropogenic disturbances in gullies may help maintain high hollow density in frequently burnt landscapes.