Developing and testing models of the drivers of anthropogenic and lightning-caused wildfire ignitions in south-eastern Australia

Clarke, Hamish; Gibson, Rebecca K.; Cirulis, Brett; Bradstock, Ross A.; Penman, Trent D.

doi:10.1016/j.jenvman.2019.01.055

Cited by 53 publications

(67 citation statements)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fire regimes of such extreme nature are likely to be restricted spatially (e.g. ridgetops and upper slopes near human populations; Bradstock, Hammill, Collins, & Price, ; Clarke, Gibson, Cirulis, Bradstock, & Penman, ) and temporally (e.g. during prolonged droughts; Fairman et al, ), though they may become more commonplace under future climates (e.g.…”

Section: Discussionmentioning

confidence: 99%

Eucalypt forests dominated by epicormic resprouters are resilient to repeated canopy fires

Collins

2019

Journal of Ecology

View full text Add to dashboard Cite

1. Wildfire occurrence and severity are projected to increase in response to anthropogenic climate change, leading to fire regimes that may exceed the limits of tolerance for some species. Plants capable of regenerating from aerial shoots following high intensity fires, termed 'epicormic resprouters', are assumed to be resilient to changes in fire regimes. However, empirical tests of the response of epicormic resprouters to extreme fire regimes, such as repeated canopy fires at short intervals, are currently lacking.2. This study examined the effect of combinations of understorey fire and canopy fire across two successive wildfires (2007, 2013) on the resilience of eucalypts that resprout epicormically. The study took place in a temperate eucalypt forest in south eastern Australia. Measures used to infer community resilience included stem topkill and damage, and seedling recruitment. It was predicted that: (a) stems will exhibit lower resistance (i.e. increased topkill and damage) to canopy fire than understorey fire; (b) recruitment will be higher following canopy fire than understorey fire; (c) prior exposure to canopy fire will reduce stem resistance and recruitment in response to subsequent wildfires; and (d) stem resistance will vary depending on bark traits.3. Topkill of saplings and small stems (<30 cm diameter at breast height) was higher in sites that recently (i.e. 2013) experienced canopy fire as opposed to understorey fire. Recent fire severity had no effect on topkill of large trees. Tree species with dense bark on the main stem and larger branches were less prone to topkill or partial stem and branch mortality than species with fibrous bark or exposed branches. Seedling recruitment was greater following canopy fire than understorey fire. Exposure to past canopy fire (i.e. in 2007) did not decrease stem resistance or recruitment. Synthesis.The results of this study suggest that communities of eucalypts that can resprout epicormically following fire will experience demographic shifts following repeated canopy fires. However, given the high resistance of large trees and rapid post-fire recovery of the seedbank, ecosystem conversion appears unlikely. The findings support the presumption that forest communities of epicormic resprouters are highly resilient to shifts in fire regimes.

show abstract

Section: Discussionmentioning

confidence: 99%

Eucalypt forests dominated by epicormic resprouters are resilient to repeated canopy fires

Collins

2019

Journal of Ecology

View full text Add to dashboard Cite

show abstract

“…Lightning-caused and power-transmission-caused ignitions have been associated with the forest fire danger index in Victoria [93]. We found that about 23% of the Black Summer forest fires in SE Australia were associated with lightning strikes as their likely ignition cause.…”

Section: Multivariate Modelsmentioning

confidence: 73%

Unveiling the Factors Responsible for Australia’s Black Summer Fires of 2019/2020

Levin

Yebra

Phinn

2021

Fire

View full text Add to dashboard Cite

The summer season of 2019–2020 has been named Australia’s Black Summer because of the large forest fires that burnt for months in southeast Australia, affecting millions of Australia’s citizens and hundreds of millions of animals and capturing global media attention. This extensive fire season has been attributed to the global climate crisis, a long drought season and extreme fire weather conditions. Our aim in this study was to examine the factors that have led some of the wildfires to burn over larger areas for a longer duration and to cause more damage to vegetation. To this end, we studied all large forest and non-forest fires (>100 km2) that burnt in Australia between September 2019 and mid-February 2020 (Australia’s Black Summer fires), focusing on the forest fires in southeast Australia. We used a segmentation algorithm to define individual polygons of large fires based on the burn date from NASA’s Visible Infrared Imaging Radiometer Suite (VIIRS) active fires product and the Moderate Resolution Imaging Spectroradiometer (MODIS) burnt area product (MCD64A1). For each of the wildfires, we calculated the following 10 response variables, which served as proxies for the fires’ extent in space and time, spread and intensity: fire area, fire duration (days), the average spread of fire (area/days), fire radiative power (FRP; as detected by NASA’s MODIS Collection 6 active fires product (MCD14ML)), two burn severity products, and changes in vegetation as a result of the fire (as calculated using the vegetation health index (VHI) derived from AVHRR and VIIRS as well as live fuel moisture content (LFMC), photosynthetic vegetation (PV) and combined photosynthetic and non-photosynthetic vegetation (PV+NPV) derived from MODIS). We also computed more than 30 climatic, vegetation and anthropogenic variables based on remotely sensed derived variables, climatic time series and land cover datasets, which served as the explanatory variables. Altogether, 391 large fires were identified for Australia’s Black Summer. These included 205 forest fires with an average area of 584 km2 and 186 non-forest fires with an average area of 445 km2; 63 of the forest fires took place in southeast (SE) Australia (the area between Fraser Island, Queensland, and Kangaroo Island, South Australia), with an average area of 1097 km2. Australia’s Black Summer forest fires burnt for more days compared with non-forest fires. Overall, the stepwise regression models were most successful at explaining the response variables for the forest fires in SE Australia (n = 63; median-adjusted R2 of 64.3%), followed by all forest fires (n = 205; median-adjusted R2 of 55.8%) and all non-forest fires (n = 186; median-adjusted R2 of 48.2%). The two response variables that were best explained by the explanatory variables used as proxies for fires’ extent, spread and intensity across all models for the Black Summer forest and non-forest fires were the change in PV due to fire (median-adjusted R2 of 69.1%) and the change in VHI due to fire (median-adjusted R2 of 66.3%). Amongst the variables we examined, vegetation and fuel-related variables (such as previous frequency of fires and the conditions of the vegetation before the fire) were found to be more prevalent in the multivariate models for explaining the response variables in comparison with climatic and anthropogenic variables. This result suggests that better management of wildland–urban interfaces and natural vegetation using cultural and prescribed burning as well as planning landscapes with less flammable and more fire-tolerant ground cover plants may reduce fire risk to communities living near forests, but this is challenging given the sheer size and diversity of ecosystems in Australia.

show abstract

“…Modeling bushfires can aid in appropriate planning and management and are in practice since the 1950s. With the advancement of computational ability of modern computers, bushfire models have become complicated and account for several variables including the interactions among climate, vegetation, terrain, and land use (Boer et al, 2019; Clarke et al, 2019; Penman et al, 2013). Similarly, machine learning approaches are also widely accepted in bushfire applications such as Clarke et al (2020) and Dutta et al (2016).…”

Section: Discussionmentioning

confidence: 99%

Causes of the Widespread 2019–2020 Australian Bushfire Season

et al. 2020

View full text Add to dashboard Cite

The recent bushfires (2019-2020) in New South Wales (NSW) Australia were catastrophic by claiming human and animal lives, affecting ecosystems, destroying infrastructure, and more. Recent studies have investigated relationships between hydroclimatic signals and past bushfires, and very recently, a few commentary papers claimed drought and fuel moisture content as the probable causes for the widespread 2019-2020 bushfires. Therefore, in this study, a novel work of encompassing a wide range of factors attributing to the recent bushfires is presented. Empirical evidence-based statistical methods are used to identify the hydroclimatic variables and geomorphic characteristics contributing to the 2019-2020 bushfires. The results highlight that ongoing drought, surface soil moisture (SSM), wind speed (WS10), relative humidity (RH), heat waves (HW), dead and live fuel moisture, and certain land cover types create favorable conditions for fire ignition and aid in fire propagation in different regions of the NSW state. The findings suggest that accounting for the above-identified variables in bushfire prediction and monitoring system are crucial in avoiding such catastrophes in the future. The overarching application of this study is developing robust and more versatile fire protection planning and management. Plain Language Summary Since the 2019-2020 Australian bushfires were catastrophic in terms of burnt area and severity, a detailed analysis of the primary causes is crucial. In this paper, several probable causes are tested statistically to establish their relationship with the burnt area. The results indicate that the ongoing drought, surface soil moisture, wind speed, relative humidity, heat waves, dead and live fuel moisture, and land cover with certain vegetation (particularly native eucalyptus and grazing land) are the primary causes of the widespread bushfire. These results are extremely critical in updating the current bushfire planning and management.

show abstract

Developing and testing models of the drivers of anthropogenic and lightning-caused wildfire ignitions in south-eastern Australia

Cited by 53 publications

References 64 publications

Eucalypt forests dominated by epicormic resprouters are resilient to repeated canopy fires

Eucalypt forests dominated by epicormic resprouters are resilient to repeated canopy fires

Unveiling the Factors Responsible for Australia’s Black Summer Fires of 2019/2020

Causes of the Widespread 2019–2020 Australian Bushfire Season

Contact Info

Product

Resources

About