RETRACTED: Propensities of Old Growth, Mature and Regrowth Wet Eucalypt Forest, and Eucalyptus nitens Plantation, to Burn During Wildfire and Suffer Fire-Induced Crown Death

Abstract

There are conflicting conclusions on how the flammability of wet eucalypt forests changes in the time after disturbances such as logging or wildfire. Some conclude that forests are most flammable in the decades following disturbance, while others conclude that disturbance has no effect on flammability. The comparative flammability of Eucalyptus nitens plantations in the same environment as wet eucalypt forest is not known. We determined fire incidence and fire severity in regrowth, mature and old growth wet eucalypt forest, and E. nitens plantation, in the Huon Valley, Tasmania after the January–February 2019 wildfire. To control for topographic variation and fire weather, we randomly selected sites within the fire footprint, then randomly located a paired site for each in different forest types in the same topographic environment within 3 km. Each pair of sites was burned on the same day. Old growth forest and plantations were the least likely to burn. Old growth and mature forest exhibited scorched eucalypt crowns to a much lesser degree than regrowth forests. In a comparison of paired sites, plantation forest was less likely to burn than combined mature and old growth forests, but in all cases of detected ignition the canopy of plantation was scorched. The lower flammability of older forests, and their importance as an increasing store of carbon, suggests that a cessation of logging outside plantations might have considerable benefits.

Managing interacting disturbances: Lessons from a case study in Australian forests

“…Similar kinds of interactions between stand age and forest flammability have been found in other parts of the world (e.g. Tiribelli, Morales, Gowda, Mermoz, & Kitzberger, 2018; Winoto‐Lewin, Sanger, & Kirkpatrick, 2020; Zald & Dunn, 2017; Zylstra, 2018). Several factors likely contribute to these stand age–flammability relationships.…”

Fire, forests and fauna (The 2020 Krebs Lecture)

“…However, evidence presented in (Attiwill et al 2014) actually showed that crown fires had occurred twice as frequently in regrowth when compared to old growth forests. Similarly, (Price and Bradstock 2012) and (Winoto-Lewin et al 2020) also found that the likelihood of crown fire declined in ash-type forests as they age. Attiwill et al (2014) have elected to ignore the broader body of evidence on relationships between logging and fire, including data in their own study.…”

“…A series of studies has shown that the severity of wildfires is influenced by the condition of the forest at the time of the fire (Bradstock and Price 2014;Lindenmayer et al 2009;Taylor et al 2014;Tiribelli et al 2018;Winoto-Lewin et al 2020;Zylstra 2009;Zylstra 2018) . A detailed empirical study after the 2009 Black Saturday wildfires in Victoria showed that logged in wet eucalypt forests that had been regenerated after harvesting were at seven times greater risk of burning at high severity than older, unlogged forests (Taylor et al 2014).…”

“…Second, reducing fire risks requires removing logging from native forests because such operations significantly increase the risks of high-severity conflagrations (Attiwill et al 2014;Bradstock and Price 2014;Taylor et al 2014;Winoto-Lewin et al 2020) . The longterm objective of such an action would be to remove the additional fire burden that arises from logging.…”

“…Third, land management agencies must work harder to significantly expand the old growth forest estate. This is critical for several reasons: (1) Old growth forest is where fire severity is lowest (Lindenmayer et al 2020b;Taylor et al 2014;Winoto-Lewin et al 2020;Zylstra 2018). (2) The old growth forest estate has declined dramatically in recent decades (Lindenmayer and Taylor 2020) and this will have major negative impacts on biodiversity, including after wildfire (through a scarcity of key biological legacies such as large burned trees).…”