Patchiness of prescribed burns in dry sclerophyll eucalypt forests in South-eastern Australia

Abstract

Prescribed burning is commonly used in eucalypt forests to reduce fire risk and minimize damage to people and property in the event of a wildfire. The dry sclerophyll forests of south-eastern Australia are naturally fire-prone. Little is known about the heterogeneity of prescribed fires in these forests. This paper reports on the spatial variability of repeated low intensity fires under two burning regimes, in both logged and unlogged forests, for a 17-year period from 1988 to 2005. Prescribed burns were extremely patchy at both the coupe and the plot scale for all treatments. Burns implemented soon after logging covered significantly greater areas than the standard prescribed burns. On the coupe scale, the extent of the burn was influenced by the average aspect of the coupe and the percent of the coupe burnt in the last fire. At the smaller plot scale, the extent of the burn was influenced by the neighbourhood burn patterns, the distance the plot was from the nearest drainage line, the time since the last fire and the percentage of the plot that was burnt in the last fire. Under operational conditions, sites on ridges are likely to burn approximately every 11 years and sites in gullies approximately every 20 years. Patchy burns achieved in this study will provide refuges for fire sensitive species and newly burnt areas for colonizing species and are therefore likely to have significantly lower ecological impacts than homogenous burns.