Grant James Williamson

University of Tasmania · School of Plant Science

Fire is an integral part of the Earth System and humans have skillfully used fire for millennia. Yet human activities are scaling up and reinforcing each other in ways that are reshaping fire patterns across the planet. We review these changes using the concept of the fire regime, which describes the timing, location, and type of fires. We then exp...

Background: We studied Riveaux Road Fire, which was ignited by multiple lightning strikes in January 2019 and burnt more than 637.19 km2 in southern Tasmania, Australia. Aims: We focused on fire weather, such as identification of dynamic wind and vegetation type, in a valley of the study area. Methods: We employed two methods: numerical weather mod...

Greenhouse gas (GHG) accounting of emissions from land use, land-use change, and forestry necessarily involves consideration of landscape fire. This is of particular importance for Australia given that natural and human fire is a common occurrence, and many ecosystems are adapted to fire, and require periodic burning for plant regeneration and ecol...

The establishment of sustainable, low-intensity fire regimes is a pressing global challenge given escalating risk of wildfire driven by climate change. Globally, colonialism and industrialisation have disrupted traditional fire management, such as Indigenous patch burning and silvo-pastoral practices, leading to substantial build-up of fuel and inc...

BACKGROUND Evidence on the relationship between air pollution and allergic sensitisation in childhood is inconsistent, and this relationship has not been investigated in the context of smoke events that are predicted to increase with climate change. Thus, we aimed to evaluate associations between exposure in two early life periods to severe levels...

Background and objective Studies linking early life exposure to air pollution and subsequent impaired lung health have focused on chronic, low-level exposures in urban settings. We aimed to determine whether in utero exposure to an acute, high-intensity air pollution episode impaired lung function 7-years later. Method We conducted a prospective c...

Background: Due to climate change, landscape fires account for an increasing proportion of air pollution emissions, and their impacts on primary and pharmaceutical care are little understood. Objectives: To evaluate associations between exposure in two early life periods to severe levels of PM2.5 from a mine fire, background PM2.5, and primary a...

Background Climate change is projected to increase environmental health hazard risks through fire-related air pollution and increased airborne pollen levels. To protect vulnerable populations, it is imperative that evidence-based and accessible interventions are available. The environmental health app, AirRater, was developed in 2015 in Australia t...

Background Information campaigns about bushfire preparedness are often based on the assumption that residents of bushfire-prone neighbourhoods underestimate their risk. However, there are complex relationships between bushfire hazard, perceived risk and adaptive action. Aims We investigate how residents’ understanding of bushfire risk relates to bi...

A neglected dimension of the fire regime concept is fire patchiness. Habitat mosaics that emerge from the grain of burned and unburned patches (pyrodiversity) are critical for the persistence of a diverse range of plant and animal species. This issue is of particular importance in frequently burned tropical Eucalyptus savannas, where coarse fire mo...

To date, most studies of fire severity, which is the ecological damage produced by a fire across all vegetation layers in an ecosystem, using remote sensing have focused on wildfires and forests, with less attention given to prescribed burns and treeless vegetation. Our research analyses a multi-decadal satellite record of fire severity in wildfire...

Sphagnum bogs in Australia are small, with a limited distribution, but of high conservation value. They are restricted to cool, wet environments that are typically fire free and are poorly adapted to recover from fire disturbance, unlike most Australian flora. Increased fire activity due to anthropogenic climate change is threatening Sphagnum bogs....

A neglected dimension of the fire regime concept is fire patchiness. Habitat mosaics that emerge from the grain of burned and unburned patches (pyrodiversity) are critical for the persistence of a diverse range of plant and animal species. This issue is of particular importance in frequently burned tropical Eucalyptus savannas, where coarse fire mo...

Fine fuel moisture content (FFMC) is a key determinant of wildfire occurrence, behaviour, and pyrogeographic patterns. Accurate determination of FFMC is laborious, hence managers and ecologists have devised a range of empirical and mechanistic measures for FFMC. These FFMC measures, however, have received limited field validation against field-base...

Wildfires are not only a natural part of many ecosystems, but they can also have disastrous consequences for humans, including in Australia. Rugged terrain adds to the difficulty of predicting fire behavior and fire spread, as fires often propagate contrary to expectations. Even though fire models generally incorporate weather, fuels, and topograph...

Colonialism has disrupted Indigenous socioecological systems around the globe, including those supported by intentional landscape burning. Because most disruptions happened centuries ago, our understanding of Indigenous fire management is largely inferential and open to debate. Here, we investigate the ecological consequences of the loss of traditi...

Background Uncontrolled wildfires in Australian temperate Eucalyptus forests produce significant smoke emissions, particularly carbon dioxide (CO 2 ) and particulates. Emissions from fires in these ecosystems, however, have received less research attention than the fires in North American conifer forests or frequently burned Australian tropical sav...

Background ‘Megafire’ is an emerging concept commonly used to describe fires that are extreme in terms of size, behaviour, and/or impacts, but the term’s meaning remains ambiguous. Approach We sought to resolve ambiguity surrounding the meaning of ‘megafire’ by conducting a structured review of the use and definition of the term in several languag...

Savanna fire management is a topic of global debate, with early dry season burning promoted as a large-scale emissions reduction opportunity. To date, discussions have centred on carbon abatement efficacy, biodiversity and cultural benefits and/or risks. Here we use a case study of Darwin, Australia to highlight smoke pollution as another critical...

Wildfires in 2019–2020 broke global records for extent and severity, affirming the arrival of the megafire era. Frequent megafires reflect changes to fire regimes that can negatively impact species and ecosystems. Here, we offer what we believe to be the first comprehensive analysis of megafire impacts on southeastern Australian vegetation communit...

Background Uncontrolled wildfires in Australian temperate Eucalyptus forests produce significant smoke emissions, particularly carbon dioxide (CO2) and particulates. Emissions from fires in these ecosystems, however, have received less research attention than the fires in North American conifer forests or frequently burned Australian tropical savan...

We analysed river flows in the Tasmanian Wilderness World Heritage Area to understand how they affect commercial whitewater rafting. Respectively, two river gauges have recorded river flows since 1953 and 1980 on the middle section of the Franklin on the Mt Fincham Track and at the bridge on the Collingwood River, a major tributary of the upper Fra...

Tasmania is a large island (68,401 km2) that lies 200 km south of the south-eastern Australian mainland [...]

There is mounting concern that global wildfire activity is shifting in frequency, intensity and seasonality in response to climate change. Fuel moisture provides a powerful means of detecting changing fire potential. Here, we use global burned area and weather reanalysis data, and the Canadian Fire Weather Index system to calculate fuel moisture tr...

The vulnerability to repeated high severity fires of tall wet eucalypt forests (TWEF) dominated by obligate seeder species is widely understood. However, 80% of Tasmania’s TWEF are dominated by resprouter species, and while these forests are more resilient to wildfire than those dominated by obligate seeders, the degree of their resilience is not w...

The 2019–20 Australian fire season was heralded as emblematic of the catastrophic harm wrought by climate change. Similarly extreme wildfire seasons have occurred across the globe in recent years. Here, we apply a pyrogeographic lens to the recent Australian fires to examine the range of causes, impacts and responses. We find that the extensive are...

Forest fire risk, and how it changes over time, has important influences on forest dynamics. Two common models describing how fire risk changes with stand development, known as flammability functions, are (a) the ‘moisture model’, where fire risk initially increases, then decreases, as a stand develops after a fire, and (b) the ‘Olson model’, where...

The temperate Eucalyptus savannas in the Midlands of Tasmania are ancient ecosystems where fire and grazing are intrinsic ecological disturbances. The arrival of Aboriginal people into Tasmania some 40,000 years ago altered natural fire regimes, and since the end of the last ice age, their skilful patch burning increased the grass cover and the abu...

The 2019–20 wildfires in eastern Australia presented a globally important opportunity to evaluate the respective roles of climatic drivers and natural and anthropogenic disturbances in causing high-severity fires. Here, we show the overwhelming dominance of fire weather in causing complete scorch or consumption of forest canopies in natural and pla...

Background Climate change is causing an increase in the frequency and severity of heatwave events, with a corresponding negative impact on human health. Health service utilisation during a heatwave is increased, with a greater risk of poor health outcomes identified for specific population groups. In this study, we examined the impact of heatwave e...

Background and objective: The link between respiratory and vascular health is well documented in adult populations. Impaired lung function is consistently associated with thicker arteries and higher incidence of cardiovascular disease. However, there are limited data on this relationship in young children and the studies that exist have focussed o...

Pollen is a well-established trigger of asthma and allergic rhinitis, yet concentration-response relationships, lagged effects, and interactions with other environmental factors remain poorly understood. Smartphone technology offers an opportunity to address these challenges using large, multi-year datasets that capture individual symptoms and expo...

Fire risk can be defined as the probability that a fire will spread across a landscape, that therefore determines the likely area burnt by a wildfire. Reliable monitoring of fire risk is essential for effective landscape management. Compilation of fire risk records enable identification of seasonal and inter-annual patterns and provide a baseline t...

During extreme air pollution events, such as bushfires, public health agencies often recommend that vulnerable individuals visit a nearby public building with central air conditioning to reduce their exposure to smoke. However, there is limited evidence that these “cleaner indoor air shelters” reduce exposure or health risks. We quantified the impa...

The relationships between productivity, fire frequency and fire severity shape the distribution of plant communities globally. Dry forests are expected to burn frequently and wet forests to burn infrequently. However, the effect of productivity on intensity and severity of wildfire is less consistent and poorly understood. One productive ecosystem...

AirRater is a free smartphone app developed in 2015, supporting individuals to protect their health from environmental hazards. It does this by providing (i) location-specific and near real-time air quality, pollen and temperature information and (ii) personal symptom tracking functionality. This research sought to evaluate user perceptions of AirR...

In flammable landscapes around the globe, longer fire seasons with larger, more severely burnt areas are causing social and economic impacts that are unsustainable. The Australian 2019–20 fire season is emblematic of this trend, burning over 8 million ha of predominately Eucalyptus forests over a six-month period. We calculated the wildfire-smoke-r...

This paper reviews information about field observations of vegetation productivity in Australia’s rangeland systems and identifies the need to establish a national initiative to collect net primary productivity (NPP) and biomass data for rangeland pastures. Productivity data are needed for vegetation and carbon model parameterisation, calibration a...

Over the Austral spring and summer of 2019/20 > 7 million ha of Eucalyptus forest and woodland, including some of Australia's most carbon dense ecosystems, were burnt on the east coast of Australia. We estimated bootstrapped mean CO2 emissions of c. 0.67 Pg, with other available estimates ranging from 0.55 to 0.85 Pg. Eucalyptus forests are renowne...

Background In the southern hemisphere summer of 2019-2020, Australia experienced its most severe bushfire season on record. Smoke from fires affected 80% of the population, with large exceedances of the Australian National Air Quality Standard for particulate air pollution recorded in all major population centres during this period. We examined if...

In the southern hemisphere summer of 2019–20, Australia experienced its most severe bushfire season on record. Smoke from fires affected 80% of the population, with large and prolonged exceedances of the Australian National Air Quality Standard for fine particulate matter (PM2.5) recorded in all major population centers. We examined if AirRater, a...

Commentary On: Oswald, W. W., Foster, D. R., Shuman, B. N., Chilton, E. S., Doucette, D. L., Duranleau, D. L. Conservation implications of limited Native American impacts in pre-contact New England. Nature Sustainability https://doi.org/10.1038/s41893-019-0466-0

Extreme fires have substantial adverse effects on society and natural ecosystems. Such events can be associated with the intense coupling of fire behaviour with the atmosphere, resulting in extreme fire characteristics such as pyrocumulonimbus cloud (pyroCb) development. Concern that anthropogenic climate change is increasing the occurrence of pyro...

The island state of Tasmania has marked seasonal variations of fine particulate matter (PM2.5) concentrations related to wood heating during winter, planned forest fires during autumn and spring, and bushfires during summer. Biomass smoke causes considerable health harms and associated costs. We estimated the historical health burden from PM2.5 att...

Previous analyses of historical aerial photography and satellite imagery have shown thickening of woody cover in Australian tropical savannas, despite increasing fire frequency. The thickening has been attributed to increasing precipitation and atmospheric CO2 enrichment. These analyses involved labour‐intensive, manual classification of vegetation...

Asthma and allergic rhinitis (or hay fever) are ubiquitous, chronic health conditions that seasonally affect a sizeable proportion of the population. Both are commonly triggered or exacerbated by environmental conditions including aeroallergens, air quality and weather. Smartphone technology offers new opportunities to identify environmental driver...

Fine particulate matter emissions (PM2.5) from landscape biomass fires, both prescribed and wild, pose a significant public health risk, with smoke exposure seasonally impacting human populations through both highly concentrated local plumes, and more dispersed regional haze. A range of technologies now exist for mapping and modeling atmospheric pa...

Smoke exposure from landscape and coal mine fires can have severe impacts on human health. The ability of health studies to accurately identify potential associations between smoke exposure and health is dependent on the techniques utilised to quantify exposure concentrations for the population at risk. The evolution of spatial modelling techniques...

The present study aimed to determine moisture thresholds for combustion of organic soils sampled from various vegetation types at 63 locations in Tasmania, Australia. To observe whether the soil sample sustained smouldering combustion, moisture content was experimentally manipulated and heat was applied. Combustion was primarily determined by moist...

Objective To evaluate whether vascular health in young children was associated with exposure to a 6-week episode of coal mine fire smoke or environmental tobacco smoke (ETS) in a retrospective cohort study. Methods Three years after a coal mine fire in Victoria, Australia, we investigated the vascular health of children either in utero (n=75) or a...

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 pyrocumulonimbus cloud (pyroCb) development. Concern that anthropogenic climate change is increasing the occurrence o...

In 2014, wildfires ignited a fire in the Morwell open cut coal mine, Australia, which burned for six weeks. This study examined associations between self-reported respiratory outcomes in adults and mine fire-related PM 2.5 smoke exposure. Self-reported data were collected as part of the Hazelwood Health Study Adult Survey. Eligible participants wer...

Background: This study assessed the association between coal-mine-fire-related fine particulate matter (PM2.5) and medical-service utilization, following a 6-week coal-mine fire in Australia, in 2014. Areas in the immediate vicinity of the mine experienced hourly mine-fire-related PM2.5 concentrations of up to 3700 μg/m3. Methods: Data on medica...

Heatwaves have been identified as a threat to human health, with this impact projected to rise in a warming climate. Gaps in local knowledge can potentially undermine appropriate policy and preparedness actions. Using a case-crossover methodology, we examined the impact of heatwave events on hospital emergency department (ED) presentations in the t...

Background: Evidence of health effects following early life exposure to short-to-medium duration of high pollution levels is extremely limited. Objectives: We aimed to evaluate the associations between: 1. intrauterine exposure to fine particulate matter (PM2.5) from coal mine fire emissions and the frequencies of general practitioner attendance...

Acknowledgements We would like to thank the Bureau of Meteorology for providing AQFx and Himawari-8 data feeds for AQVx. We would also like to thank the Department of Environment, Land, Water and Planning and the Environment Protection Authority, Victoria for their support with the deployment of the SMOG units and for their input to AQVx. We would...

Aim Understanding past distributions of people across the landscape is key to understanding how people used, affected and related to the natural environment. Here, we use habitat suitability modelling to represent the landscape distribution of Tasmanian Aboriginal archaeological sites and assess the implications for patterns of past human activity....

Rational In 2014, local wildfires ignited a fire in the Morwell open cut coal mine, in south-eastern Australia, which burned for six weeks. Limited research was available regarding the respiratory health effects of coal mine fire-related PM2.5 smoke exposure. Objective This study examined associations between self-reported respiratory outcomes in a...

Paleofire studies frequently discount the impact of human activities in past fire regimes. Globally, we know that a common pattern of anthropogenic burning regimes is to burn many small patches at high frequency, thereby generating landscape heterogeneity. Is this type of anthropogenic pyrodiversity necessarily obscured in paleofire records because...

Background and objective: Long-term respiratory risks following exposure to relatively short periods of poor air quality early in life are unknown. We aimed to evaluate the association between exposure to a 6-week episode of air pollution from a coal mine fire in children aged <2 years, and their lung function 3 years after the fire. Methods: We...

The extensible Biomass Smoke Validated Events Database is an ongoing, community driven, collection of air pollution events which are known to be caused by vegetation fires such as bushfires (also known as wildfire and wildland fires), or prescribed fuel reduction burns, and wood heaters. This is useful for researchers of health impacts who need to...