@article {bnh-7954, title = {Demographic effects of severe fire in montane shrublands on Tasmania{\textquoteright}s Central Plateau}, number = {658}, year = {2021}, month = {04/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

Australian montane sclerophyll shrubland vegetation is considered to be resilient to infrequent severe fire but this may not be the case in Tasmanian shrublands. Our research reports on the regeneration response of a Tasmanian non-coniferous woody montane shrubland following a severe fire. The 2019 Great Pine Tier fire in the Central Plateau Conservation Area was a severe crown fire that killed all above ground vegetation in the shrubland. Our field survey revealed that less than 1\% of the burnt plants were not top-killed by the fire, and only 5\% of the burnt plants were observed to be resprouting one year following the fire. Such a low resprouting rate means the resilience of the shrubland depends on seedling regeneration from aerial and soil seedbanks or colonisation from plants outside the fire ground. The low number of resprouters within the shrubland suggest that it may not be as resilient to fire as mainland Australian montane shrubland. As a consequence, our research highlights the fragility of the shrubland under a warming climate and potential increase in fire frequency.

}, keywords = {demographic, effects, Fire, montane, severe, shrublands, Tasmania}, issn = {658}, author = {Judy Foulkes and Steven Leonard and David Bowman} } @article {bnh-8127, title = {The southwest Tasmania fires of summer 2018-2019 - a post event review capability study}, year = {2021}, month = {07/2021}, pages = {64}, institution = {Zurich}, address = {Sydney}, abstract = {

The summer of 2018-19 (December 2018 {\textendash} February 2019) was devastating for the Australian state of Tasmania. Fire services were overwhelmed by the multiple, large fires that burned over 200,000 ha across the western half of the island from the end of December through to early March. This report analyses these fires using the Zurich Flood Resilience Alliance{\textquoteright}s Post Event Review Capability (PERC) methodology. It focuses on community and business resilience; while there have been several reviews into firefighting operations, a more systemic view of resilience is less common.

The summer 2018/19 fires officially began on 24 December 2018, in one of the hottest and driest summers on record. On 15 January 2019, 2402 dry lightning strikes hit the state, igniting 70 fires that formed into four massive fire complexes. More than 210,000 hectares burned, including 95,000 hectares in the Tasmanian Wilderness World Heritage Area (TWWHA). Fortunately, no deaths were directly attributed to the bushfire, although an unknown number of people are believed to have died due to smoke and 114 injuries or accidents were recorded.

The event saw a significant and protracted evacuation, with the Huonville evacuation centre open for 15 days, accommodating up to 700 people daily. The lingering effects on impacted communities are still being felt. It resulted in the destruction of tourism assets, forestry resource and globally precious, protected ecosystems of the TWWHA. Smoke from the fires impacted health and the burgeoning viticulture industry in Tasmania. These impacts, along with others, have had significant flow-on effects to the already-struggling Tasmanian economy and communities.

There is much to learn from this event for Tasmania and other jurisdictions which will likely face similar events. This report outlines the risk landscape in southwest Tasmania, examining trends in climate-change charged bushfire conditions, exposure of people and assets, and their vulnerabilities. It outlines what happened during the event, with a focus on the community safety response. Direct and indirect impacts on people and economies are explored. Key insights are identified across all phases of the disaster cycle. Below we present an abridged version of the final recommendations of the study

}, keywords = {Capability, fires, post event, review, southwest, summer, Tasmania}, url = {https://www.zurich.com.au/content/dam/au-documents/news/the-southwest-tasmania-fires-of-summer-2018-2019-a-post-event-review-capability-study.pdf}, author = {Adriana Keating and John Handmer} } @article {bnh-8165, title = {Using pre- and post-fire LiDAR to assess the severity of the 2019 Tasmanian bushfires}, number = {698}, year = {2021}, month = {08/2021}, institution = {Bushfire and Natural Hazards CRC}, address = {MELBOURNE}, abstract = {

In January 2019, over 64,000 ha of bushland burned in the Riveaux Road fire in Tasmania{\textquoteright}s southern forests. Most of area burned occurred in tall wet eucalypt forest. These forests are considered to be highly flammable in dry conditions, but fires are infrequent due to the generally cool, wet climate in which they grow. As a result, limited data exists on the behaviour and effects of wildfire in these forests. Prior to these fires, extensive areas of these southern forests have been studied in-depth. In 2014, a large area of the forests that burned were mapped with aerial LiDAR, a remote-sensing technology that can characterise three-dimensional forest structure. Further, in 2016, detailed field-based measurements of fuel load, structure, and hazard were taken at 12 permanent plots which subsequently burned in 2019. Hence, the 2019 fires in Tasmania represent a globally-rare opportunity to characterise the severity of a large wildfire using pre-fire and post-fire data. In October 2019, the Department of Primary Industries, Parks, Water and Environment (DPIPWE) in Tasmania, along with five other BNHCRC end-users and the University of Tasmania, launched a project to use remote-sensing and field-based data to create a detailed case study of the 2019 Riveaux Rd. Fire, and to untangle the drivers of fire severity in tall wet eucalypt forests.\  To do this we (i) remeasured plots to assess tree mortality and changes in fuel loads post fire; (ii) acquired LiDAR data from a transect across a burned buttongrass-forest boundary on the Weld River enabling comparison with pre-fire LiDAR data; (iii) established baseline postfire LiDAR buttongrass-forest boundary transect on the Huon River at Blakes Opening.\  Here we describe the data sets and report some preliminary analyses.

}, keywords = {Bushfire, fire severity, Lidar, post-fire, pre-fire, Tasmania}, issn = {698}, author = {Furlaud, James M. and Arko Lucieer and Scott Foyster and Anna Matala and David Bowman} } @article {bnh-7344, title = {Variation in Eucalyptus delegatensis post-fire recovery strategies: The Tasmanian subspecies is a resprouter whereas the mainland Australian subspecies is an obligate seeder}, journal = {Forest Ecology and Management}, volume = {473}, year = {2020}, month = {10/2020}, abstract = {

Eucalyptus delegatensis\ is native to the Australian Alps (subsp.\ delegatensis) and montane Tasmania (subsp.\ tasmaniensis).\ Post-fire regeneration mechanisms of the obligate-seeder subspecies on the Australian mainland are well-known, but less is known about the resprouter Tasmanian subspecies. In January 2016, large tracts of\ Eucalyptus delegatensis\ forests in central Tasmania, logged at different intensities, were burnt by low- and high-severity fire. We used statistical modelling to understand how tree survival, vegetative regeneration and seedling recruitment differed according to understorey type, fire severity, logging intensity and tree size (DBH). Fire severity, defined as unburnt, low-severity (fire scarring on the stem and/or lower canopy burnt) and high-severity (full canopy burnt), affected tree survival: 84\% of trees were alive in unburnt transects, compared with 43\% in low-severity transects and 36\% in high-severity transects. Epicormic resprouting was the dominant mode of vegetative recovery, with\ \<\ 1\% of total trees recovering solely by basal resprouting. Fire severity significantly affected epicormic resprouting, with 70\% of live stems resprouting post-fire in low-severity transects and 99\% in high-severity transects, compared with 4\% in unburnt transects. Tree survival was strongly influenced by tree size: in high-severity transects, 24\% of trees with DBH\ \<\ 20\ cm were alive, compared with 88\% of trees with DBH\ >=\ 20\ cm. These differences in survival were primarily because large trees were more likely to resprout epicormically, with epicormic shoots present on 24\% of live trees with DBH\ \<\ 20\ cm, compared with 79\% of live trees with DBH\ >=\ 80\ cm. The strong effect of tree size renders clear-felled forests especially vulnerable to fire during the several decades when all the regenerating trees are small (DBH\ \<\ 20\ cm). Seedling recruitment was uncommon, independent of understorey type and logging intensity, but with higher occurrence on high-severity (54\%) than low-severity (19\%) or unburnt (15\%) transects. When present, seedling densities were typically low: median\ =\ 400 and maximum\ =\ 4{\textperiodcentered}104\ seedlings ha-1. This study highlights that mature forests of\ Eucalyptus delegatensis\ in Tasmania are more resilient (able to return to pre-disturbance conditions) to single high-severity fires than their mainland counterparts, because they can recover more quickly through epicormic resprouting. However, clear-felling reduces this resilience for several decades because it decreases median tree size and, hence, leads to higher post-fire mortality. It is difficult to predict how the Tasmanian subspecies will respond to an increased frequency of high-severity fires associated with a projected warmer and drier climate.

}, keywords = {Clear-felling, Epicormic resprouting, Eucalyptus delegatensis, fire severity, Seedlings, Tasmania, Tree size, Tree survival, Understorey type}, doi = {https://doi.org/10.1016/j.foreco.2020.118292}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0378112720310616}, author = {Dario Rodriguez-Cubillo and Lynda Prior and David Bowman} } @article {bnh-6392, title = {Evolution of an extreme Pyrocumulonimbus-driven wildfire event in Tasmania, Australia}, journal = {Natural Hazards and Earth System Sciences}, year = {2019}, month = {12/2019}, abstract = {

Extreme fires have substantial adverse effects on society and natural ecosystems. Such events can be associated with intense coupling of fire behaviour with the atmosphere, resulting in extreme fire characteristics such as pyrocumulonimbuscloud (pyroCb) development. Concern that anthropogenic climate change is increasing the occurrence of pyroCbs globally is driving more focused research into these meteorological phenomena. Using 6-minute scans from a nearby weather radar, we describe the development of a pyroCb during the afternoon of 4 January 2013 above the Forcett-Dunalley fire in south-eastern Tasmania. We relate storm development to: (1) near-surface weather using the McArthur Forest Fire Danger Index (FFDI), and the C-Haines Index, a measure of the vertical atmospheric stability and dryness both derived from gridded weather reanalysis for Tasmania (BARRA-TA), and (2) a chronosequence of fire severity derived from remote sensing. We show that the pyroCb rapidly developed over a 24-minute period in the afternoon of 4 January, with the cloud top reaching a height of 15 km. The pyroCb was associated with a highly unstable atmosphere (C-Haines 10-11) and Severe-marginally Extreme (FFDI 60-75) near-surface fire weather, and formed over an area of forest that was severely burned (total crown defoliation). We use spatial patterns of elevated fire weather in Tasmania, and fire weather during major runs of large wildfires in Tasmania for the period 2007-2016 to geographically and historically contextualise this pyroCb event. Although the Forcett-Dunalley fire is the only known record of a pyroCb in Tasmania, our results show that eastern and south-eastern Tasmania are prone to the conjunction of high FFDI and C-Haines values that have been associated with pyroCb development. Our findings have implications for fire weather forecasting and wildfire management, and highlight the vulnerability of southeast Tasmania to extreme fire events.

}, keywords = {C-Haines, extreme fire, fire severity, Fire weather, McArthur Forest Fire Danger Index, pyrocumulonimbus, smoke plume injection, Tasmania, wildland fire}, doi = {https://doi.org/10.5194/nhess-2019-354}, url = {https://www.nat-hazards-earth-syst-sci-discuss.net/nhess-2019-354/}, author = {Mercy Ndalila and Grant Williamson and Paul Fox-Hughes and Jason J. Sharples and David Bowman} } @article {bnh-6321, title = {Geographic Patterns of Fire Severity Following an Extreme Eucalyptus Forest Fire in Southern Australia: 2013 Forcett-Dunalley Fire }, journal = {Fire}, volume = {1}, year = {2018}, month = {10/2018}, abstract = {

Fire severity is an important characteristic of fire regimes; however, global assessments of fire regimes typically focus more on fire frequency and burnt area. Our objective in this case study is to use multiple lines of evidence to understand fire severity and intensity patterns and their environmental correlates in the extreme 2013 Forcett-Dunalley fire in southeast Tasmania, Australia. We use maximum likelihood classification of aerial photography, and fire behavior equations, to report on fire severity and intensity patterns, and compare the performance of multiple thresholds of the normalised burn ratio (dNBR) and normalized difference vegetation index (dNDVI) (from pre- and post-fire Landsat 7 images) against classified aerial photography. We investigate how vegetation, topography, and fire weather, and therefore intensity, influenced fire severity patterns. According to the aerial photographic classification, the fire burnt 25,950 ha of which 5\% burnt at low severities, 17\% at medium severity, 32\% at high severity, 23\% at very high severities, while 22\% contained unburnt patches. Generalized linear modelling revealed that fire severity was strongly influenced by slope angle, aspect, and interactions between vegetation type and fire weather (FFDI) ranging from moderate (12) to catastrophic (\>100). Extreme fire weather, which occurred in 2\% of the total fire duration of the fire (16 days), caused the fire to burn nearly half (46\%) of the total area of the fireground and resulted in modelled extreme fireline intensities among all vegetation types, including an inferred peak of 68,000 kW{\textperiodcentered}m-1 in dry forest. The best satellite-based severity map was the site-specific dNBR (45\% congruence with aerial photography) showing dNBR potential in Eucalyptus forests, but the reliability of this approach must be assessed using aerial photography, and/or ground assessment.

}, keywords = {aerial photography, Eucalyptus forest, fire intensity, fire severity mapping, generalized linear modelling, geospatial validation, normalized burn ratio, Tasmania}, doi = {https://doi.org/10.3390/fire1030040}, url = {https://www.mdpi.com/2571-6255/1/3/40}, author = {Mercy Ndalila and Grant Williamson and David Bowman} }