Returning Fire to Degraded Temperate Grassy Woodland Fragments Requires Fine-Scale Management Interventions to Promote Trees: Insights From the Beaufront Experiment

Abstract

Temperate grassy woodlands were once widespread in southeast Australia and were shaped by fire regimes imposed by Indigenous peoples. Today, they persist as scattered fragments in matrices of highly modified farmland, where fire is rare and eucalypt trees are in decline. Returning fire to these fragments is a suggested approach to reduce fuels and stimulate eucalypt recruitment. We implemented a single round of small, low-intensity surface fires in a woodland fragment in the Tasmanian Midlands and assessed adult eucalypt mortality and juvenile recruitment. The fires were set during mild fire weather, were tended by 4–15 people, and fire-fighting vehicles were used to extinguish burning trees. Still, the fires killed 7% of adult eucalypts (18 trees), mostly due to cambial girdling which occurred where burning litter and coarse woody debris at the base of the trees initiated smouldering fires in thick bark on the lower trunks. Seedling recruitment was restricted to ash beds near trees with viable seed crops. Seedlings survived only if protected from mammalian herbivores. Herbivore protection also increased the growth of lignotuberous sprouts after fire. Our findings demonstrate that eucalypt trees in degraded woodland fragments may be vulnerable to low-intensity surface fire. We make recommendations as to how managers may burn woodland fragments in ways that avoid killing eucalypt trees and enhance postfire recruitment, enabling transition to more sustainable fire regimes.