Impact of intense disturbance on the structure and composition of wet-eucalypt forests: A case study from the Tasmanian 2016 wildfires

• Published in: PLOS ONE
• Main Authors: Lunn, TJ, Gerwin, M, Buettel, JC, Brook, BW
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science 2018
• Subjects: Agricultural; Veterinary and Food Sciences; Forestry sciences; Forest ecosystems; Antarc*; Antarctica
• Online Access: https://doi.org/10.1371/journal.pone.0200905; http://www.ncbi.nlm.nih.gov/pubmed/30028860; http://ecite.utas.edu.au/144158

Fire is a key process in eucalypt communities, exerting a strong influence on the composition, structure and functioning of forests. Much of the research on the fire response of temperate, wet-sclerophyll trees in Australia comes from Victoria, where the dominant eucalypt is Eucalyptus regnans . In contrast, central and northern Tasmanian forests, dominated by Eucalyptus delegatensis , are relatively understudied. There is a need to determine whether Tasmanian wet-sclerophyll forests, though the same forest type in name, are functionally different in floristics and response to fire. Here we document the forest community response to a natural wildfire event in Tasmania - using opportunistic before/after control/impact (BACI) data from pre-existing monitoring plots. Uniting pre- and post-fire floristic data, we quantified mortality and regeneration of eucalypt, acacia and other dominant tree species, and tree ferns, Dicksonia antarctica , in response to wildfire. We also evaluated the density of eucalypt and acacia seedling establishment between burnt and unburnt forests, and quantified faunal responses to fire. Despite moderate-to-high intensity burning in patches across the plot, mortality of eucalypts, acacias and tree ferns due to fire were low. By contrast, fire-sensitive rainforest species showed low survival, though were able to persist in unburnt refugia. Eucalypt and acacia seedling regeneration was high in the burnt plot, suggesting that E . delegatensis forests regenerate without stand-replacing fire events. This contrasts to Victorian E . regnans forests, whose persistence is dependent on high-severity stand-replacing events. We also found some group-specific avifaunal and invertebrate responses to the fire event, which are broadly reflective of responses documented in other Victorian-based studies. Our results have implications for Tasmanian wet-forest silvicultural practices, which are based on the principle of stand-replacement after fire. The broader relevance of this work to forest ecology is in demonstrating the serendipitous opportunities that can arise with baseline monitoring plots.