scholarly journals Wildfire refugia in forests: Severe fire weather and drought mute the influence of topography and fuel age

2019 ◽  
Vol 25 (11) ◽  
pp. 3829-3843 ◽  
Author(s):  
Luke Collins ◽  
Andrew F. Bennett ◽  
Steve W. J. Leonard ◽  
Trent D. Penman
Keyword(s):  
2018 ◽  
Vol 27 (9) ◽  
pp. 609 ◽  
Author(s):  
Kelly M. Dixon ◽  
Geoffrey J. Cary ◽  
Graeme L. Worboys ◽  
Julian Seddon ◽  
Philip Gibbons

Fuel hazard is often assumed to increase with fuel age, or the time-since-fire. However, studies on fuel hazard in long-unburned forests are scarce. We measured overall fuel hazard in Eucalyptus forests and woodlands in south-eastern Australia at 81 sites where time-since-fire spans 0.5 years to at least 96 years. Overall fuel hazard was higher in forests and woodlands burned 6–12 years previously than those unburned for at least 96 years. The probability of high, very high or extreme overall fuel hazard – which is an operational threshold considered to equate with almost no chance of wildfire suppression in severe fire-weather – was highest 0.5–12 years post-fire, and lowest where fire had not occurred for at least 96 years. Frequent burning can maintain forest understorey in an early successional ‘shrubby’ state, leading to higher overall fuel hazard than forests where a lack of fire is associated with the senescence of shrubs. Protecting long-unburned sites from fire and managing to transition a larger proportion of forest to a long-unburned state may benefit fuel-hazard management within these forests in the long-term.


1991 ◽  
Vol 1 (2) ◽  
pp. 97 ◽  
Author(s):  
R Mees

Under severe fire weather conditions arson is believed to be the primary cause of large wildland fires in southern California. Wildland fire suppression personnel and the public use the the expression "This weather brings out the arsonists" to indicate their awareness of the high potential for large arson-caused fires under these conditions. To determine the accuracy of this statement, fire occurrence and weather data were analyzed for four southern California National Forests for a 10-year period (1975–1984). The results showed that the proportion of arson and non-arson person-caused fires remained the same under most fire-danger conditions; however, a much higher percentage of arson fires became large fires when fire danger was severe. Furthermore, the timing of the arsonist contributed to the frequent occurrence of large arson fires. The data presented here refute the idea that most arson fires occur under severe weather conditions and at the same time-validate the utility of maintaining arson prevention programs during most weather conditions.


2002 ◽  
Vol 11 (4) ◽  
pp. 213 ◽  
Author(s):  
Mary Ann Jenkins

The Haines Index, an operational fire–weather index introduced in 1988 and based on the observed stability and moisture content of the near-surface atmosphere, has been a useful indicator of the potential for high-risk fires in low wind conditions and flat terrain. The Haines Index is of limited use, however, as a predictor of actual fire behavior. To develop a fire–weather index to predict severe or erratic wildfire behavior, an understanding of how the ambient lower-level atmospheric stability and moisture affects the growth of a wildfire is needed. This study is a first step in this process. This study investigates, through four comparative numerical simulations with a coupled wildfire–atmosphere model, the sensitivity of wildland fires to atmospheric stability and moisture, and in the process explores the correspondence between atmospheric stability and moisture, wildfire behavior, and the Haines Index. In the first three fire simulations, the model atmosphere was initially set to identical moisture but different instability conditions that correspond to Haines Indexes for low, moderate, and high potential for severe fire development. In the fourth fire simulation, the initial atmospheric and moisture conditions were for a high-risk fire Haines Index rating, but different from the initial conditions of dryness and stability of the previous experiments. The study indicates that high-risk fire development is sensitive to near-surface atmospheric stability and moisture, and that there is a range of atmospheric stability and moisture conditions that is important to the development of severe or erratic fire behavior, and that this range is within the atmospheric stability and moisture conditions represented by a Haines Index for high potential for severe fire. The analyses also suggest that there is a substantial latitude of fire behavior for fires rated as this Index, indicating that this Index should be further divided, or refined.


2016 ◽  
Vol 66 (3) ◽  
pp. 281-313
Author(s):  
Timothy Brown ◽  
Graham Mills ◽  
Sarah Harris ◽  
Domagoj Podnar ◽  
Hauss Reinbold ◽  
...  
Keyword(s):  

Fire ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 32
Author(s):  
Judy A. Foulkes ◽  
Lynda D. Prior ◽  
Steven W. J. Leonard ◽  
David M. J. S. Bowman

Australian montane sclerophyll shrubland vegetation is widely considered to be resilient to infrequent severe fire, but this may not be the case in Tasmania. Here, we report on the vegetative and seedling regeneration response of a Tasmanian non-coniferous woody montane shrubland following a severe fire, which burned much of the Great Pine Tier in the Central Plateau Conservation Area during the 2018–2019 fire season when a historically anomalously large area was burned in central Tasmania. Our field survey of a representative area burned by severe crown fire revealed that more than 99% of the shrubland plants were top-killed, with only 5% of the burnt plants 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 colonization from plants outside the burned area. Woody species’ seedling densities were variable but generally low (25 m−2). The low number of resprouters, and reliance on seedlings for recovery, suggest the shrubland may not be as resilient to fire as mainland Australian montane shrubland, particularly given a warming climate and likely increase in fire frequency.


2021 ◽  
Author(s):  
Andrew G. Marshall ◽  
Paul A. Gregory ◽  
Catherine O. de Burgh-Day ◽  
Morwenna Griffiths
Keyword(s):  

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