Bark hazard

Consider the bushfire hazard from bark when planning rehabilitation in bushfire prone areas

Fire spotting is a prominent issue in eucalypt forest fires and is one of the main ways that homes are ignited and destroyed in bushfire prone areas. The incidence of spot fires is closely related to the type of bark on the trees being consumed by fire. Therefore, consideration of how different types of bark can influence the incidence of fire spotting is important when planning rehabilitation in bushfire prone areas.

The Overall Fuel Hazard Assessment Guide (Victorian Government Department of Sustainability and Environment 2010) identifies three different types of bark which can influence fire spotting. These include:

• Stringybark and other fine fibrous bark types – these barks can produce massive quantities of embers and short distance spotting;
• Ribbon and candle bark types – these barks can produce substantial quantities of embers and result in both short and long distance spotting up to several kilometres from the main fire front; and
• Other barks types, eg ironbark, platy bark, paperbark, slab bark – these barks produce limited quantities of embers and spotting is infrequent and unlikely to hinder fire control.

Rehabilitation plantings often focus on providing koala food and habitat trees. Therefore, in this paper we have categorised some of the commonly used koala food and habitat trees into the three different types of bark.

The information in the table indicates that an area of rehabilitation plantings in a bushfire prone area, which favours koala food and habitat trees such as E. carnea, E. microcorys, E. resinifera, E. tindaliae and Lophostemon suaveolens will increase the bushfire hazard to adjacent buildings because of ember attack.

The guidelines below will help reduce the bushfire hazard from rehabilitation plantings in bushfire prone areas:

• At least 90 % of the koala food and habitat trees in the rehabilitation area should be trees with ‘other bark types’.
• Koala food and habitat trees with ‘stringybark and other fine fibrous bark types’ and ‘ribbon and candle bark types’ should be planted as far as possible from buildings, fire trails and fire-fighter water supply points.
• Koala food and habitat trees with ‘stringybark and other fine fibrous bark types’ and ‘ribbon and candle bark types’ can be planted as specimen trees in landscaped gardens and mowed areas, where they are unlikely to be impacted by fire.