Changes in Lightning Fire Incidence in the Tasmanian Wilderness World Heritage Area, 1980–2016

Abstract

The Tasmanian Wilderness World Heritage Area (TWWHA) has globally significant natural and cultural values, some of which are dependent on the absence of fire or the presence of particular fire regimes. Planned burning is currently used to reduce the risk of loss of world heritage values from unplanned fires, but large and damaging fires still occur, with lightning as the primary ignition source. Lightning-caused fire was rare in the TWWHA before 2000. There has since been an increase in both the number of fires following lightning storms and the area burnt by these fires. In the absence of a direct measurement of lightning strike incidence, we tested whether changes in rainfall, soil dryness and fuel load were responsible for these changes in fire incidence and extent. There were no relationships between these variables and the incidence of fires associated with lightning, but the variability in the Soil Dryness Index and the mean of 25% of driest values did predict both the number and area of fires. Thus, it appears that an increase in the proportion of lightning strikes that occur in dry conditions has increased ignition efficiency. These changes have important implications for the management of the TWWHA’s values, as higher projected fuel loads and drier climates could result in a further increase in the number of fires associated with lightning.

Prescribed burning in south-eastern Australia: history and future directions

“…According to Styger et al (2018), lightning-caused wildfire was rare before 2000 in the Tasmanian Wilderness World Heritage Area, but there has been an increase in the proportion of lightning strikes occurring there during dry conditions, resulting in large, damaging wildfires. In response, prescribed burning is being increasingly used to reduce the risk of loss of World Heritage values due to wildfire.…”

Population collapse and retreat to fire refugia of the Tasmanian endemic conifer Athrotaxis selaginoides following the transition from Aboriginal to European fire management

“…Close to a century after the fires, we found no live A. selaginoides trees and vanishingly few A. selaginoides seedlings. We suggest it is highly unlikely that A. selaginoides forest at Abrotanella Rise catchment can re‐occupy this site given (a) the poor dispersal of the species; (b) slow growth to reproductive maturity of the few seedlings that occur in this catchment; and (c) the need for long fire‐free interval (Gibson et al, ), which is an increasingly unlikely in this region given probable shift in future fire regimes (Harris et al, ; Mariani et al, ) due to regional drying trends and associated rapid increased occurrence of lightning‐lit fires (Fox‐Hughes, Harris, Lee, Grose, & Bindoff, ; Mariani et al, ; Styger, Marsden‐Smedley, & Kirkpatrick, ). The interlocking demographic effects of slow growth to reproductive maturity, limited seed establishment in the face of increased fire risk conforms to the interval squeeze model of Enright et al ().…”

“…It remains unclear however, whether topographic fire refugia will be sufficient to buffer extant A. selaginoides populations in the Southern Ranges or elsewhere in Tasmania against increasingly frequent fires. Increased human‐set fires and lightning ignitions combined and a drying and warming trend driven by anthropogenic climate change have been reported and forecasted for Tasmania (Harris et al, ; Mariani et al, , ; Styger et al, ). For instance, since the data for this study were collected, two very active fire seasons (in 2016 and 2019) have killed stands of Athrotaxis forests in Tasmania (e.g.…”

Development of EST microsatellite markers for the Tasmanian palaeoendemic conifer Lagarostrobos franklinii (Hook. f.) Quinn (Podocarpaceae)

“…Overall up to 15 % of its total extent has been lost to hydroelectric schemes (Reid, et al 1999) while a further 7 % has been impacted by fire (DPIPWE 2011) with very little recovery (Buckley 1997). Furthermore, recent increases in the frequency of fires ignited by dry lightning in western Tasmania (Styger, et al 2018) pose a severe threat to the species.…”