No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Long-term impacts of prescribed burning on regional extent and incidence of wildfires—Evidence from 50 years of active fire management in SW Australian forests
Abstract
Prescribed burning is advocated for the sustainable management of fire-prone ecosystems for its capacity to reduce fuel loads and mitigate large high-intensity wildfires. However, there is a lack of comprehensive field evidence on which to base predictions of the benefits of prescribed burning for meeting either wildfire hazard reduction or conservation goals. Australian eucalypt forests are among the very few forest types in the world where prescribed burning has been practised long enough and at a large enough spatial scale to quantify its effect on the incidence and extent of unplanned fires. Nevertheless even for Australian forests evidence of the effectiveness of prescribed burning remains fragmented and largely unpublished in the scientific literature.
... Other natural and human intervention variables, such as fire prevention measures, land use changes, and climate change, could potentially affect the relationship between fire suppression and fire regimes, leading to variations in the findings of the included studies. Fire prevention measures, such as education and legislative regulations, landscape-scale fuel treatments, and prescribed burning [34,121,122], can effectively reduce ignitions and the accumulation of fuel caused by long-term fire suppression [34,37,[74][75][76][123][124][125]. Therefore, there has been no escalation of fire regimes, despite aggressive fire suppression, due to these fire prevention measures in regions of the US [95,126], Canada [127], France [88], and Australia [121,123,124]. ...
... Fire prevention measures, such as education and legislative regulations, landscape-scale fuel treatments, and prescribed burning [34,121,122], can effectively reduce ignitions and the accumulation of fuel caused by long-term fire suppression [34,37,[74][75][76][123][124][125]. Therefore, there has been no escalation of fire regimes, despite aggressive fire suppression, due to these fire prevention measures in regions of the US [95,126], Canada [127], France [88], and Australia [121,123,124]. Land use changes could also interact with fire suppression and alter the fire regimes. ...
... Land use changes could also interact with fire suppression and alter the fire regimes. Fragmentation caused by roads [121,125,128], grazing land [36], and agricultural fields [39,128] in flammable areas could reduce fuel continuity and the capacity for fire spread, resulting in lower fire frequency and burned area. For example, under the same aggressive fire suppression policy, there was a contrasting alteration in fire regimes between a region with livestock and a region without livestock [36]. ...
Fire suppression has become a fundamental approach for shaping contemporary wildfire regimes. However, a growing body of research suggests that aggressive fire suppression can increase high-intensity wildfires, creating the wildfire paradox. Whether the strategy always triggers the paradox remains a topic of ongoing debate. The role of fire suppression in altering wildfire regimes in diverse socio-ecological systems and associated research designs demands a deeper understanding. To reconcile these controversies and synthesize the existing knowledge, a systematic review has been conducted to screen 974 studies on the relationship between fire suppression and wildfire regimes. The rigorous screening process led to the selection of 37 studies that met our stringent criteria for inclusion. The selected literature was quantitatively analyzed in terms of study areas, study design and methods, and the impact of fire suppression on wildfire regimes. Several critical findings were revealed: 1. Numerous studies have focused on northern mid- and high-latitude biomes, neglecting tropical savannas where wildfires are frequent and intense. Further exploration in these regions is imperative. 2. Existing studies have predominantly employed methods such as difference analysis, regression analysis, and scenario simulations. Appropriate methods could be selected based on the study area, data availability, and understanding of fire regimes. 3. Despite the consensus that fire suppression reduces the total burned area, the emergence of the wildfire paradox remains controversial, with approximately equal amounts of the literature supporting and contradicting the wildfire paradox. A noteworthy pattern was observed: the wildfire paradox is more likely to occur in fuel-limited systems, specific vegetation types, and smaller scale and longer term studies. This systematic review highlights that the occurrence of the wildfire paradox is intricately tied to ecosystem feedback mechanisms for suppression and the research scale adopted. It is necessary to incorporate a comprehensive and multi-scale assessment of how local wildlands respond to suppression into wildfire management policy-making processes. This assessment will ensure a more informed and effective wildfire management strategy adapted to local conditions.
... Aboriginal Australians have been using controlled burning practices for tens of thousands of years (Bowman, 1998;Gammage, 2013), while Europeans introduced incident response-based wildfire control (Keating and Handmer, 2013;Pyne, 1991). PB has been used in Australia since the mid-1950s to reduce fuels and increase the likelihood of efficient wildfire suppression (Boer et al., 2009;Burrows and McCaw, 2013;Russell-Smith et al., 2013). Some studies argue that PB can be ineffective in reducing bushfire risk since it can stimulate the regrowth of flammable materials and create more fuel; increase fire risk and flammability, due to drying of the forest floor, and lead to faster spread of fire because of loss in forest density (Altangerel and Kull, 2013). ...
... Measuring bushfire management outcomes: environmental, social, and economic performance 3.1.1. Environmental assessment of bushfire management tools PB regimes should be designed to produce the least amount of greenhouse gas emissions, especially due to the growing environmental concerns worldwide (Boer et al., 2009). When it comes to the debate about applying prescribed fire to reduce carbon emissions from fire-prone forests, quantification of its effectiveness is crucial (Boer et al., 2009;Bradstock and Williams, 2009;Narayan et al., 2007). ...
... Environmental assessment of bushfire management tools PB regimes should be designed to produce the least amount of greenhouse gas emissions, especially due to the growing environmental concerns worldwide (Boer et al., 2009). When it comes to the debate about applying prescribed fire to reduce carbon emissions from fire-prone forests, quantification of its effectiveness is crucial (Boer et al., 2009;Bradstock and Williams, 2009;Narayan et al., 2007). ...
Fires are an important aspect of environmental ecology; however, they are also one of the most widespread destructive forces impacting natural ecosystems as well as property, human health, water and other resources. Urban sprawl is driving the construction of new homes and facilities into fire-vulnerable areas. This growth, combined with a warmer climate, is likely to make the consequences of wildfires more severe. To reduce wildfires and associated risks, a variety of hazard reduction practices are implemented, such as prescribed burning (PB) and mechanical fuel load reduction (MFLR). PB can reduce forest fuel load; however, it has adverse effects on air quality and human health, and should not be applied close to residential areas due to risks of fire escape. On the other hand, MFLR releases less greenhouse gasses and does not impose risks to residential areas. However, it is more expensive to implement. We suggest that environmental, economic and social costs of various mitigation tools should be taken into account when choosing the most appropriate fire mitigation approach and propose a conceptual framework, which can do it. We show that applying GIS methods and life cycle assessment we can produce a more reasonable comparison that can, for example, include the benefits that can be generated by using collected biomass for bioenergy or in timber industries. This framework can assist decision makers to find the optimal combinations of hazard reduction practices for various specific conditions and locations.
... The climate envelope of the woylie is also expected to shift by up to 100% by 2080, leading to further declines (Stewart et al., 2018). Shifts in climate are likely to affect fire regimes, as the incidence of unplanned wildfire increases during drought in this region (Boer et al., 2009). The combination of fire and drought will further impact species, their habitats and the effectiveness of recovery actions (Collins et al., 2019;. ...
... wandoo). Fire is a prominent disturbance in the region, with regular prescribed burns and occasional wildfires (Boer et al., 2009). Most of the fire within the study region is prescribed fire, and the current fire management policy stipulates that 45% of the study region be less than 6 years postfire at any one time to reduce the likelihood of large-scale severe fires. ...
... Therefore, fire history in the region is driven mostly by anthropogenic factors rather than environmental factors (e.g. rainfall) (Boer et al., 2009). Most of the study area has been subject to one or more native timber harvesting events over the last 100 years and while most of the area is now either Nature Reserve or National Park, about a third is State Forest and remains available for timber harvesting until the end of 2023 (Wayne et al., 2006). ...
Ecosystem management in the face of global change requires understanding how co‐occurring threats affect species and communities. Such an understanding allows for effective management strategies to be identified and implemented. An important component of this is differentiating between factors that are within (e.g., invasive predators) or outside (e.g., drought, large wildfires) of a local manager's control. In the global biodiversity hotspot of south‐western Australia, small and medium‐sized mammal species are severely affected by anthropogenic threats and environmental disturbances, including invasive predators, fire, and declining rainfall. However, the relative importance of different drivers has not been quantified. We used data from a long‐term monitoring program to fit Bayesian state‐space models that estimated spatial and temporal changes in the relative abundance of four threatened mammal species: the woylie (Bettongia penicillata), chuditch (Dasyurus geoffroii), koomal (Trichosurus vulpecula) and quenda (Isoodon fusciventor). We then use Bayesian structural equation modelling to identify the direct and indirect drivers of population changes, and scenario analysis to forecast population responses to future environmental change. We found that habitat loss or conversion and reduced primary productivity (caused by rainfall declines) had greater effects on species’ spatial and temporal population change than the range of fire and invasive predator (the red fox Vulpes vulpes) management actions observed in the study area. Scenario analysis revealed that a greater extent of severe fire and further rainfall declines predicted under climate change, operating in concert are likely to further reduce the abundance of these species, but may be mitigated partially by invasive predator control. Considering both historical and future drivers of population change is necessary to identify the factors that risk species recovery. Given that both anthropogenic pressures and environmental disturbances can undermine conservation efforts, managers must consider how the relative benefit of conservation actions will be shaped by ongoing global change.
... Aboriginal Australians have been using controlled burning practices for tens of thousands of years (Bowman, 1998;Gammage, 2013), while Europeans introduced incident response-based wildfire control (Keating and Handmer, 2013;Pyne, 1991). PB has been used in Australia since the mid-1950s to reduce fuels and increase the likelihood of efficient wildfire suppression (Boer et al., 2009;Burrows and McCaw, 2013;Russell-Smith et al., 2013). Some studies argue that PB can be ineffective in reducing bushfire risk since it can stimulate the regrowth of flammable materials and create more fuel; increase fire risk and flammability, due to drying of the forest floor, and lead to faster spread of fire because of loss in forest density (Altangerel and Kull, 2013). ...
... Measuring bushfire management outcomes: environmental, social, and economic performance 3.1.1. Environmental assessment of bushfire management tools PB regimes should be designed to produce the least amount of greenhouse gas emissions, especially due to the growing environmental concerns worldwide (Boer et al., 2009). When it comes to the debate about applying prescribed fire to reduce carbon emissions from fire-prone forests, quantification of its effectiveness is crucial (Boer et al., 2009;Bradstock and Williams, 2009;Narayan et al., 2007). ...
... Environmental assessment of bushfire management tools PB regimes should be designed to produce the least amount of greenhouse gas emissions, especially due to the growing environmental concerns worldwide (Boer et al., 2009). When it comes to the debate about applying prescribed fire to reduce carbon emissions from fire-prone forests, quantification of its effectiveness is crucial (Boer et al., 2009;Bradstock and Williams, 2009;Narayan et al., 2007). ...
... Fig. 3. Distribution of log-transformed wildfire size before (PrePB, 1985(PrePB, -2004 and during (PB, 2005(PB, -2020 the prescribed burning era: (a) histograms and empirical density curves; (b) cumulative density curves. over preceding years (Boer et al., 2009;Price and Bradstock, 2011;Price et al., 2015a). Leverage can be expressed as return-for-effort, e.g., a leverage of 0.25 (1:4) implies that wildfire extent can be decreased by 1 ha by treating 4 ha. ...
... Simulation studies (e.g., Loehle, 2004;King et al., 2006;Price, 2012) may sound appealing, because simulation data are easier to obtain than observational data and leverage can be determined for distinct scenarios, but simulation results are conditioned by the assumptions and uncertainty inherent to fire spread models. Observed PB leverage can vary from 0.25 (Boer et al., 2009) or 0.30 (Price and Bradstock, 2011) in Australian eucalypt forests to 1 in northern Australia savannas . Elsewhere, past burned extent leverage varies widely, including no leverage or even negative leverage, implying a 'fire-follows-fire' process (Price et al., 2015a). ...
... Elsewhere, past burned extent leverage varies widely, including no leverage or even negative leverage, implying a 'fire-follows-fire' process (Price et al., 2015a). Besides its use to assess PB effectiveness, with implications other than decreasing wildfire extent (e. g., carbon emissions mitigation; Bradstock et al., 2012), leverage estimates can be used by fire management agencies to determine the extent and spatiotemporal pattern of PB required to reduce wildfire hazard to an acceptable level, and thus optimize its planning (Boer et al., 2009). ...
... This discussion can be better understood when placed into the context of the recent history of debate over fire management in Australia-particularly in the south-west. Fire management in the region rests heavily on the claim that there is a negative correlation between the areas of planned and unplanned fire (Boer et al., 2009;Burrows & McCaw, 2013;Sneeuwjagt, 2011). That is, examination of a subset of the West Australian fire history dataset suggested that wildfire area has increased as the rate of prescribed burning decreased. ...
... Photo: Melissa Howe & Nathan McQuoid. than wildfire (Boer et al., 2009). Further, suppression of wildfires has been made more difficult due to the area over which this policy has rendered the vegetation as more flammable regrowth Zylstra et al., 2022Zylstra et al., , 2024. ...
Empirical evidence in scientific literature shows that forest flammability in south‐western Australia declines as forests recover from disturbance, indicating that current policies mandating disturbance may be counterproductive. Zylstra et al. (2023) used mechanistic modelling to explain this trend in Red Tingle (Eucalyptus jacksonii) forest in south‐western Australia. McCaw. (2024) have questioned the validity of the modelling, advancing hypothetical arguments as to why one of the inputs (‘suspended litter’) is incorrect and re‐asserting the need for the current policy.
The primary argument by McCaw. (2024) depends upon the redefinition of a component of surface litter into suspended litter. The published definition of near‐surface fuel defines necromass as ‘suspended’ fuel only if it is suspended in living plants or collapsed shrubs. McCaw. (2024) removed this requirement, so that a component of surface fuel was incorrectly measured as ‘suspended’ fuel long after the plants that might suspend it had self‐thinned from the landscape.
This physically impossible assertion was supported by an empirical study led by an architect of the policy and utilising the same redefinition of suspended litter, also reporting physically impossible findings as a result.
Given the well‐documented decline in wildfire likelihood in long‐unburnt forest, the claim by McCaw. (2024) that suspended litter does not decline suggests at best that such litter plays a lesser role than previously believed. The approaches used by McCaw. (2024) to defend Government policy should be understood in context of growing international concerns around scientific suppression used in defence of Government policy.
Read the free Plain Language Summary for this article on the Journal blog.
... Approximately 68% of the region is legislatively protected as conservation reserve tenure managed by the state government's conservation agency (DBCA 2023a). Primary vegetation disturbance in the region is through prescribed burning and wildfires, and infestations of the soil-borne pathogen Phytophthora cinnamomi (Boer et al 2009, McDougall et al 2024. ...
... The flora and fauna in the region display a high degree of endemism (Rix et al 2015). Similar to the Warren region, the South-Jarrah forests and woodlands are subject to frequent wildfires and P. cinnamomi infestation (Boer et al 2009, McDougall et al 2024. ...
Worsening climate change impacts are amplifying the need for accurate estimates of vegetation structure and aboveground biomass density (AGBD) to assess changes in biodiversity and carbon storage. In Australia, increasing wildfire frequency and interest in the role of forests in the carbon cycle necessitates biomass mapping across large geographic extents to monitor forest change. The availability of spaceborne Light Detection and Ranging optimised for vegetation structure mapping through the Global Ecosystem Dynamics Investigation (GEDI) provides an opportunity for large-scale forest AGBD estimates of higher accuracy. This study assessed the use of the GEDI canopy height product to predict woody AGBD across five vegetation types in Western Australia: tall eucalypt forests, eucalypt open‒woodlands, low-lying heathland, tropical eucalypt savannas, and tussock and hummock grasslands. Canopy height models were developed using random forest regressions trained on GEDI canopy height discrete point data. Predictor variables included spectral bands and vegetation indices derived from synthetic aperture radar Sentinel‒1 data, and multispectral Landsat and Sentinel‒2 data. AGBD was subsequently estimated using power-law models derived by relating the predicted canopy heights to field AGBD plots. Mapping was conducted for 2020 and 2021. The accuracy of canopy height predictions varied with height quantiles; models underestimated the height of taller trees and overestimated the height of smaller trees. A similar underestimation and overestimation trend was observed for the AGBD estimates. The mean carbon stock was estimated at 69.0 ± 12.0 MgCha⁻¹ in the tall eucalypt forests of the Warren region; 33.8 ± 5.0 MgCha⁻¹ for the open eucalypt woodlands in the South Jarrah region; 7.1 ± 1.4 MgCha⁻¹ for the heathland and shrublands in the Geraldton Sandplains region; 43.9 ± 4.9 MgCha⁻¹ for the Kimberley eucalypt savanna; and 3.9 ± 1.0 MgCha⁻¹ for the Kimberley savanna grasslands. This approach provides a useful framework for the future development of this process for fire management, and habitat health monitoring.
... Boer et al 2009) because Zylstra et al (2022) examined patterns in flammability (frequency of fire at a point) over a much longer time-span. Although the findings of Zylstra et al (2022)concurred with earlier studies by finding a brief period of low flammability immediately after fire (Boer et al 2009, McCaw et al 2012, McCaw 2013, it contrasted with such studies by showing that flammability later declined. Because the long-unburnt (untreated) state of the forest had comparatively low flammability, Zylstra et al (2022)concluded that the decades-long pulse of flammability that followed a burning treatment was caused by the treatment. ...
... This has therefore likely affected all fire history analyses used to underpin management in the region (e.g. Boer et al 2009). ...
Our previous analysis of mapped records of forest fires in National Parks in Southwestern Australia showed that fires initiated a pulse in flammability (the likelihood of a point being burned by wildfire), but that flammability declined as forests matured (Zylstra et al 2022 Environ. Res. Lett. 17 044022). This reduction in flammability was contrary to that expected from modelling used by the West Australian Government to guide management, but consistent with expectations from peer-reviewed fire behaviour science and published ecological drivers of fire behaviour. Miller et al (2024 Environ. Res. Lett.) argued that our reported decline in flammability of long-unburnt forest is an artefact of poor data quality including flawed records kept by the West Australian Government, along with fewer and smaller sample sizes in long-unburnt forest. These problems, they claim, biased these age-classes toward values of zero flammability due to a rounding error. Critically, Miller et al (2024 Environ. Res. Lett.) did not test their hypothesis by repeating the analysis with these data removed. Here, we show that Miller et al’s (2024 Environ. Res. Lett.) concerns are dependent upon the mathematical fallacy that rounding errors only occur in one direction (rounding flammability down to zero), when they have an equal likelihood of rounding upward and elevating flammability. The effect of this is to introduce noise rather than bias. We tested their hypothesis by repeating the analysis of Zylstra et al (2022 Environ. Res. Lett. 17 044022) with a better suited statistical method on an improved and expanded dataset after removing the small patches that Miller et al (2024 Environ. Res. Lett.) proposed would bias the findings. Contrary to the objections of Miller et al (2024 Environ. Res. Lett.), removing lower quality data revealed that the mature forests were even less flammable than expected, so that only annual prescribed burning could reduce bushfire likelihood below that in forests unburnt for 56 years or more. Our findings highlight the role of prescribed burning in creating a more flammable landscape.
... Multiple studies have directly or indirectly addressed fire-on-fire interactions in the western USA (Collins et al. 2009;Parks et al. 2012Parks et al. , 2013Parks et al. , 2015Parks et al. , 2016Price et al. 2012;Belval et al. 2019;Yocom et al. 2019Yocom et al. , 2022 and Australia (Boer et al. 2009;Price et al. 2015b) but are scarce elsewhere (Price et al. 2015a). Previous work in southern Europe was based on simulation and dealt with the effects of past burned area (prescribed fire and wildfire scars) and firefighting (Piñol et al. 2005(Piñol et al. , 2007Regos et al. 2014) or modeled how past burned area influenced subsequent burned area (Price et al. 2015a;Duane et al. 2019;Davim et al. 2021Davim et al. , 2022. ...
... Our results are consistent with those pointing to a short-lived effect of TSF on wildfire extent in Portugal (Price et al. 2015a;Fernandes et al. 2019), Spain (Duane et al. 2019), and in temperate warm to hot summer climates elsewhere (Boer et al. 2009;Price et al. 2012). Previous work reports that the area treated with prescribed fire and not reburned by a subsequent wildfire was 1.5 times greater for fuels < 3.5 years old (Davim et al. 2021) and that the effect of prescribed burning in decreasing wildfire extent lasted for about 5 years, whereas the corresponding effect of wildfire lasted 7 years (Davim et al. 2022). ...
Background The study of wildfire interactions (i.e., spread limitation and reburns) is gaining traction as a means of describing the self-limiting process of fire spread in the landscape and has important management implications but has scarcely been attempted in Europe. We examined to what extent previously burned areas restricted the development of individual large wildfires (> 500 ha) in mainland Portugal.
Results For the 1984–2021 period, we (1) modeled the proportion of large wildfire perimeters coinciding with transitions to shorter time since fire (TSF), i.e., locations where fire spread ceased upon encountering assumedly less flammable fuels, and (2) characterized the prevalence of different TSF in the composition of the area burned by large wildfires in relation to available TSF. Only 4% of the large wildfires did not comprise edges intersecting past wildfires. Low TSF (especially up to 8 years) resulted in large-wildfire perimeter limitation at TSF transitions. This effect was further enhanced by high historical burn probability and proximity to roadways and watercourses. Perimeter limitation did also increase under high (but not very high or extreme) fire danger, benefiting from maximum seasonal firefighting preparedness. TSF prevalence in the composition of large-wildfire area was extremely variable and thus an overall weak pattern emerged, with minimum and maximum prevalence respectively at TSF < 2 years and TSF ≥ 6 years.
Conclusions Large wildfire limitation in Portugal is hampered by fast fuel build-up after fire, indicating a short-lived fire-hazard reduction effect under the prevailing Mediterranean humid climate of the study region. Nonetheless, such effect should be considered when planning fuel-reduction treatments and can be used opportunistically during large-wildfire suppression operations.
... Analysis of the occurrence and extent of planned and unplanned fires can provide useful insight into the effectiveness of prescribed burning in managing fire regimes at the landscape scale over decadal time periods. Boer et al. (2009) demonstrated a strong inverse relationship between the extent of prescribed burning and unplanned fire in the Warren region of south-west Western Australia over 45 years, during which the fraction of the study area burnt annually by planned fire ranged from 4 % to 11 %. Landscape scale studies of fire occurrence in the Sydney region have shown that fuel reduction by previous fire and prescribed burning has a measurable, but limited effect on fire spread and on the extent of unplanned fire (Price and Bradstock, 2010;Price and Bradstock, 2011). ...
... Use of prescribed fire to achieve fuel reduction and other land management objectives has declined in southern Australia over recent decades (Parliament of Victoria, 2008;Boer et al. 2009;Adams and Attiwill, 2011;Burrows and McCaw, 2013). This is despite the fact that most post-fire inquiries at State and federal level following major fire events have called for the use of prescribed burning to be maintained or increased; in the past decade these have included inquiries by independent experts and panels ( Doogan, 2006), and a Royal Commission (Teague et al. 2010). ...
Prescribed fire has been used in a coordinated manner to manage eucalypt forests and woodlands in Australia since the 1950s. The impetus for planned burning arose from the need to reduce the impact of extensive, high intensity fires on life, property and commercial forest values. Prescribed fire is increasingly recognised as also playing an important role in mitigating undesirable effects of high intensity fires on environmental values including soil, water and biodiversity. Critical elements for an effective prescribed fire program include a sound understanding of fire behaviour, reliable weather forecasts, an experienced and flexible workforce, and organisational commitment to adaptive management involving planning, monitoring and applied research. Implementation of prescribed fire programs has been closely linked with, and is dependent upon, the development of burning guides for particular forest types through empirical field research. The contribution of prescribed fire to mitigating the effects of extensive, high intensity fires can be quantified in a variety of ways using basic combustion science, well-documented case studies, analysis of historical fire statistics, and simulation. Done at appropriate spatial and temporal scales, fuel reduction improves the safety, efficiency and effectiveness of fire suppression and mitigates damage from unplanned bushfires. Social and political factors can significantly influence the conduct and effectiveness of prescribed fire programs, and engagement with the community is essential during planning, implementation and post-fire monitoring phases to ensure that the role of prescribed fire in land management is properly recognised and understood.
... A high leverage value shows potential for high fuel treatment benefits as it indicates that a relatively small area treated can result in a significant reduction in wildfire area, presumably by providing firefighters greater opportunities to limit fire size. Global analyses of fuel treatment leverage show that while fuel treatments can be associated with lower area burned in wildfire, leverage tends to be low and highly variable across locations [17,58,59]. Given its importance in determining the economic benefits of treatment, land managers should consider the encounter rate or potential leverage of any proposed treatment project. ...
... Further, using statistical modeling or wildfire simulation methods, several studies have examined how fuel treatment area influences wildfire patterns and losses over time. Generally, increased treatment area leads to reductions in wildfire area burned, burn probability, and wildfire-induced damages and losses [19,23,49,58,60]. However, since fuel treatment leverage varies widely based on ecosystem and fuel type [59], the scale of treatment at which cost effectiveness is optimized also varies by region [19]. ...
This review synthesizes the scientific literature on fuel treatment economics published since 2013 with a focus on its implications for land managers and policy makers. We review the literature on whether fuel treatments are financially viable for land management agencies at the time of implementation, as well as over the lifespan of fuel treatment effectiveness. We also review the literature that considers the broad benefits of fuel treatments across multiple sectors of society. Most studies find that fuel treatments are not financially viable for land management agencies based on revenue generated from forest products, biomass, or carbon credits at the time of implementation. Fuel treatments also tend to not be financially viable based on future management costs savings (fire suppression and rehabilitation costs) or averted losses in forest products from wildfire over the lifespan of treatment effectiveness. Similarly, most studies that consider benefits beyond those accruing to land management agencies find that the benefits from any single category (e.g., damage to structures and infrastructure, critical watersheds, air quality, or ecosystem values) are not sufficient to offset treatment costs. Overall, the recent literature suggests that fuel treatment projects are more likely to have benefits that exceed costs if they generate benefits in multiple categories simultaneously. The literature also documents tremendous variability in benefits and costs across regions and between projects within regions, which poses a challenge to reaching general conclusions about the benefits and costs of fuel treatments at programmatic scales, and suggests that practitioners should proceed with caution when trying to extrapolate the benefits and costs for a prospective fuel treatment project from estimates reported in the previous literature.
... Such fires have prompted widespread discussions on how fire within forests and other vegetation types might be managed to maintain ecosystem integrity , as well as to limit the loss of human life and damage to property and infrastructure (Moritz et al., 2014;Covington and Pyne, 2020). Several kinds of human intervention aimed at reducing fire severity and burnt area are commonly applied, including mechanical thinning (Noss et al., 2006;Kalies and Kent, 2016; but see Taylor et al., 2020) and prescribed burning (Fernandes and Botelho, 2003;Boer et al., 2009;McCaw, 2013;Tolhurst and McCarthy, 2016). ...
Prescribed burning is a key tool in land management globally used to reduce wildfire risks and achieve ecological, cultural and resource management objectives across both natural and human systems. Despite its widespread application, research on prescribed burning is marked by significant gaps. Subsequently, we posed the following research questions: (1) What are the key research topics that define international, peer-reviewed literature on prescribed burning? (2) What are the temporal and spatial trends of these topics? (3) What are the relationships between the national income of a given country and the trends in research topics? And, (4) What are the most salient knowledge gaps in peer-reviewed prescribed burning research, and how can they be addressed? We used structural topic modelling and geoparsing to conduct a detailed text analysis of 7878 peer-reviewed articles on prescribed burning. We revealed that research on prescribed burning is dominated by studies from high-income countries, particularly the United States. This highlights a geographical bias that may skew global understanding and application of prescribed burning practices. Our topic modelling revealed the most prevalent topics to be Fire Regimes and Landscape Biodiversity Management, whilst topics such as Air Pollution & Health, and Wildfire Risk Management gained prominence in recent years. Our analysis highlighted a disconnect between forestry-related research and broader landscape management topics. This finding emphasises the need for more interdisciplinary research, and research on the use and effects of prescribed burning in diverse ecosystems and underrepresented regions, particularly in the context of climate change.
... One key tool in combatting the risks of severe wildfires is the controlled application of fire to remove dry fuel, known as prescribed burning [29,30]. Cultural fires, which have long been used by many Native American tribes, are one category of prescribed fires, but the majority of prescribed fires in the U.S. are those managed by non-tribal fire agencies [31]. ...
Background
Prescribed burning is an important fuel management tool to prevent severe wildfires. There is a pressing need to increase its application to reduce dry fuels in the western United States, a region that has experienced many damaging wildfires. Public support for this practice is tempered by concern around smoke impacts and escape risks. This study aims to understand how recent experiences with wildfire smoke and perceived risk of smoke events affect public support for prescribed burning.
Methods
Data were from the May 2023 Household Emergency Preparedness Survey, an online panel survey of 1,727 adults in 12 western conterminous states, applying survey weights to reflect the underlying population demographics. In weighted logistic regression models, we evaluated associations between predictor variables (past experiences with smoke, wildfire risk perception) and support for prescribed burns in general or near a respondent’s neighborhood, adjusting for age, race/ethnicity, gender, education, household income, and wildland urban interface status. Mediation models were used to assess whether perceived risk of smoke exposure mediates the relationship between recent smoke experience and support for prescribed burning.
Results
Approximately two-thirds of the population supported prescribed burning in general, and more than half supported prescribed burning near their neighborhood. 44% reported experiencing a smoke event in the past 3 years, which increased the odds of support for prescribed burning in general (OR = 2.03, 95%CI 1.51–2.74) and near their neighborhood (OR = 1.59, 95% CI 1.20–2.09). High perceived risk of future smoke impacts was associated with support for prescribed burns in general (adjusted OR = 1.66, 95% CI = 1.15–2.39) and near their residence (adjusted OR = 1.72, 95%CI = 1.23–2.39). Although only trending towards significance, perceived future risk mediated 16.9% (p = 0.066) of the association between recent smoke experience and support for prescribed burning nearby. Among those who experienced recent smoke events, reporting high degrees of overall smoke impacts or outdoor air quality impacts were positively associated with support for prescribed burns.
Conclusions
Recent experience with wildfire smoke and perceived future risk are strongly associated with support for prescribed burns. Educational campaigns can apply these findings to improve public support toward prescribed fire activities and funding to reduce wildfire risks and protect public health.
... The study assumed a 10-year effectiveness for prescribed burning (Fiedler & Keegan, 2003;Loehle, 2004), which was specific to the region studied. The longevity of Rx effects varies across regions depending on influencing factors, typically ranging between 4 and 10 years posttreatment (Boer et al., 2009;Kobziar et al., 2015;Reilly et al., 2016;Susaeta & Carney, 2023). To enhance the applicability of Rx models, the longevity of Rx can be represented by a function incorporating regional parameters such as vegetation type and climate conditions Fonseca et al., 2022;Hood et al., 2020). ...
Prescribed burning is an essential forest management tool that requires strategic planning to effectively address its multidimensional impacts, particularly given the influence of global climate change on fire behavior. Despite the inherent complexity in planning prescribed burns, limited efforts have been made to comprehensively identify the critical elements necessary for formulating effective models. In this work, we present a systematic review of the literature on optimization and decision models for prescribed burning, analyzing 471 academic papers published in the last 25 years. Our study identifies four main types of models: spatial‐allocation, spatial‐extent, temporal‐only, and spatial–temporal. We observe a growing number of studies on modeling prescribed burning, primarily due to the expansion in spatial‐allocation and spatial–temporal models. There is also an increase in complexity as the models consider more elements affecting prescribed burning effectiveness. We identify the essential components for optimization models, including stakeholders, decision variables, objectives, and influential factors, to enhance model practicality. The review also examines solution techniques, such as integer programming in spatial allocation, stochastic dynamic programming in probabilistic models, and multiobjective programming in balancing trade‐offs. These techniques' strengths and limitations are discussed to help researchers adapt methods to specific challenges in prescribed burning optimization. In addition, we investigate general assumptions in the models and challenges in relaxation to enhance practicality. Lastly, we propose future research to develop more comprehensive models incorporating dynamic fire behaviors, stakeholder preferences, and long‐term impacts. Enhancing these models' accuracy and applicability will enable decision‐makers to better manage wildfire treatment outcomes.
... Several options exist for reducing fuels 24 . Prescribed and cultural burning are often considered as the most effective strategy, as they remove both live and dead fuels, but they need to be applied over large scales to be effective 25,26 . It is often found that prescribed re is even more effective when accompanied by thinning that follows pyro-silvicultural principles 27 . ...
The European Union has recently passed the Nature Restoration Law (NRL) which, among others, seeks to increase the cover of forest reserves protected for biodiversity and, globally, the Kunming-Montreal Global Biodiversity Framework similarly seeks to expand protected areas. Here we test whether a trade-off exists between protected areas expansion and fire activity, leading to a higher exposure to fire for the population in protected areas, because they often harbour more biomass and occur in remote areas. We analysed forest fires affecting 14,892,174 ha, and intersecting 10,999 protected areas, across fire-prone European Temperate and Mediterranean forest biomes, and in similar ecosystems within California, Chile and Australia. Protected areas were being disproportionally affected by fire within most Temperate biomes, and fire severity was 20% higher within protected areas also in Mediterranean biomes. Population in the periphery of forest areas was up to 16 times more likely to be exposed to large wildfires when their environment was within, or near, protected areas. Enhanced fire activity in protected areas was driven by a combination of fuel loads, accessibility and abiotic factors. Wildfire prevention and mitigation must be central goals in the development of the NRL and other conservation/restoration programs to diminish population exposure and fire severity.
... The jarrah forest has a canopy dominated by jarrah Eucalyptus marginata and marri Corymbia calophylla trees, a mid-storey of smaller trees and tall shrubs, and an understorey primarily comprised of forbs and small shrubs (Bell & Heddle, 1989). The region has had a broadscale prescribed programme in operation since the 1960s, which aims to manage wildfire risk by reducing fuel loads (Boer et al., 2009;Burrows & McCaw, 2013). The current policy is to maintain 45% of fuels in forested landscapes such that they are unlikely to support high-intensity and difficult to control wildfires (Howard et al., 2020). ...
Prescribed burning is the primary method used to reduce wildfire risk in a range of ecosystems globally. Knowledge of how animal populations respond to prescribed burns is essential for designing fuel management plans that are sensitive to ecological values. We conducted a before–after, control‐impact experiment in the temperate jarrah forest ecosystem of south‐western Australia to examine how reptiles respond to season of burning (spring or autumn) and time since burning (0–5 years). Through pitfall trapping at 10 survey grids over 7 years, we captured 1808 reptiles from 22 species. Bayesian mixed effects models revealed that six of the eight species analysed showed either a decrease or increase in capture rate at burnt compared to unburnt sites, and most of these effects only occurred within the first 2 years post fire. Species richness showed a weak negative response to one autumn burn and no relationship with time since fire. Fire effects were more common in autumn compared to spring burns, which is likely a reflection of differing fire severities. These results suggest that prescribed burning can temporarily reduce habitat suitability and abundance for some species, particularly those that rely on leaf litter for shelter and foraging. Our findings emphasise the dynamic nature of reptile responses to prescribed burns and underscore the importance of considering both fire seasonality and recency of burning in wildlife management plans.
... The incidence of uncontrollable wildfires in the southwest is strongly inhibited for six years following prescribed burning. 88 The inverse relationship between landscape-scale prescribed fire with the subsequent extent of wildfires is especially tight once 8% of the landscape is treated annually (meaning an area is burnt on a notional rotation every 12 years or so) but is lost very quickly and exponentially if the percentage declines further. 89 Severe fire events and seasons are then inevitable, but random. ...
This article examines the damaging 1937 bushfires, driven by a captured cyclone,
and probably the single largest recorded fire event in southwest Australia. Few
disasters have resonated in southwest people’s memory as these fires, yet the written history is scant. The fires showed it is unsafe to live in the southwest in a landscape of long-unburnt forest. They led, after 1937, to the intensification of fire management, including expanded prescribed burning, which had proved effective where practised, and to strengthening of both fire management legislation and the rural fire brigade system. Weaknesses of the Group Settlement Scheme were exposed. The paper addresses how to avoid a similar catastrophe today, tempered by the contemporary concerns about ecological resilience and the preferred levels of human intervention in the landscape. We conclude that fire mosaics with substantial areas of low-aged fuel are needed to break up fire-runs and to provide opportunities for suppression. We discuss strategies to achieve this, including the potential for even finer-scale mosaics.
... Restoration practices such as prescribed fire and mechanical thinning (Hanberry et al. 2017) are widely used to emulate the effects of natural disturbances which stabilize open woodland ecosystems and have been shown to increase oak regeneration and maintain biodiversity (Brose et al. 2013;Vander Yacht et al. 2020). More broadly, prescribed fire has improved or maintained the quality of woodland ecosystems in ecoregions in western North America (Brown et al. 2019;Hoffman et al. 2019;Saab et al. 2022), Australia (Boer et al. 2009;Burrows and McCaw 2013;Evans and Russell-Smith 2020) and southern Europe (Vilà-Vilardell et al. 2023;Fernández-Guisuraga and Fernandes 2024). ...
Temperate woodlands are biodiverse natural communities threatened by land use change and fire suppression. Excluding historic disturbance regimes of periodic groundfires from woodlands causes degradation, resulting from changes in the plant community and subsequent biodiversity loss. Restoration, through prescribed fire and tree thinning, can reverse biodiversity losses, however, because the diversity of woodland species spans many taxa, efficiently quantifying biodiversity can be challenging. We assessed whether soundscapes in an eastern North American woodland reflect biodiversity changes during restoration measured in a concurrent multitrophic field study. In five restored and five degraded woodland sites in Wisconsin, USA, we sampled vegetation, measured arthropod biomass, conducted bird surveys, and recorded soundscapes for five days of every 15-day period from May to August 2022. We calculated two complementary acoustic indices: Soundscape Saturation, which focuses on all acoustically active species, and Acoustic Complexity Index (ACI), which was developed to study vocalizing birds. We used generalized additive models to predict both indices based on Julian date, time of day, and level of habitat degradation. We found that restored woodlands had higher arthropod biomass, and higher richness and abundance of breeding birds. Additionally, soundscapes in restored sites had higher mean Soundscape Saturation and higher mean ACI. Restored woodland acoustic indices exhibited greater magnitudes of daily and seasonal peaks. We conclude that woodland restoration results in higher soundscape saturation and complexity, due to greater richness and abundance of vocalizing animals. This bioacoustic signature of restoration offers a promising monitoring tool for efficiently documenting differences in woodland biodiversity.
... Our results do not necessarily apply directly outside the context of this geographic scope, but this study does contribute to a better understanding of the ways in which treatments interact with wildfires. Globally, studies in Mediterranean and Australian ecosystems have found that prescribed burning can result in lower fire severity of subsequent wildfires, however this effect seems to be slightly shorter lived (~2-6 years) than we found in our region (Boer et al., 2009;Collins et al., 2023;Espinosa et al., 2019;Fernández-Guisuraga and Fernandes, 2024;Hislop et al., 2020;Tolhurst and McCarthy, 2016). In forests that historically burned in high-severity fire regimes, such as boreal forests, different types of fuel treatments may be employed (e.g. ...
Increased understanding of how mechanical thinning, prescribed burning, and wildfire affect subsequent wildfire
severity is urgently needed as people and forests face a growing wildfire crisis. In response, we reviewed scientific
literature for the US West and completed a meta-analysis that answered three questions: (1) How much do
treatments reduce wildfire severity within treated areas? (2) How do the effects vary with treatment type,
treatment age, and forest type? (3) How does fire weather moderate the effects of treatments? We found overwhelming
evidence that mechanical thinning with prescribed burning, mechanical thinning with pile burning,
and prescribed burning only are effective at reducing subsequent wildfire severity, resulting in reductions in
severity between 62% and 72% relative to untreated areas. In comparison, thinning only was less effective –
underscoring the importance of treating surface fuels when mitigating wildfire severity is the management goal.
The efficacy of these treatments did not vary among forest types assessed in this study and was high across a
range of fire weather conditions. Prior wildfire had more complex impacts on subsequent wildfire severity, which
varied with forest type and initial wildfire severity. Across treatment types, we found that effectiveness of
treatments declined over time, with the mean reduction in wildfire severity decreasing more than twofold when
wildfire occurred greater than 10 years after initial treatment. Our meta-analysis provides up-to-date information
on the extent to which active forest management reduces wildfire severity and facilitates better outcomes for
people and forests during future wildfire events.
... Often, prescribed fire results in lower burn severity -defined here as the loss of or change in aboveground and belowground organic matter, while recognising that individual studies use various metrics to measure severity (Keeley 2009). Prescribed burns may have multiple ignition points (Molina et al. 2022) and may be implemented when conditions are optimal for containment (Baijnath-Rodino et al. 2022), potentially leading to different duration, seasonality, spatial patterns and progression than wildfires (Boer et al. 2009). As a result of unique physical characteristics, prescribed burns and wildfire differ in their landscape-scale effects. ...
Prescribed burning is a key management strategy within fire-adapted systems, and improved monitoring approaches are needed to evaluate its effectiveness in achieving social-ecological outcomes. Remote sensing provides opportunities to analyse the impacts of prescribed burning, yet a comprehensive understanding of the applications of remote sensing for prescribed burn research is lacking. We conduct a literature review of 120 peer-reviewed publications to synthesise the research aims, methodologies, limitations and future directions of remote sensing for the analysis of prescribed fire. Studies evaluating management outcomes found prescribed burning effective for wildfire risk reduction, yet few analysed co-benefits or trade-offs with other management goals. Most studies use passive, spaceborne, low spatial resolution sensors, characterised in the literature as consistent and accessible data sources but limited in detecting small, low-severity and short-duration fires characteristic of prescribed burns. In contrast, active remote sensing approaches including LiDAR are less frequently employed, but show promise for highly accurate, spatially explicit 3D vegetation and fuel load mapping. Remote sensing advances toward higher spatial resolution, more frequent revisit, denser spectral sampling and more data across the electromagnetic spectrum are critical to advancing prescribed fire research, addressing current methodological gaps, and improving fuels and fire management capacity.
... Additionally, Western Australia generally had higher fire frequencies than other states at the start of the analysis period, primarily due to a widespread prescribed burning program that began in the 1960s (24). The negative trend in fire frequency observed in Western Australia since 1980 is likely due to both the effectiveness of the prescribed burning program in reducing wildfire occurrence (25) and a decline in the area treated by prescribed burns over time (24). ...
Human actions are causing widespread increases in fire size, frequency, and severity in diverse ecosystems globally. This alteration of fire regimes is considered a threat to numerous animal species, but empirical evidence of how fire regimes are shifting within both threatened species’ ranges and protected areas is scarce, particularly at large spatial and temporal scales. We used a big data approach to quantify multidecadal changes in fire regimes in southern Australia from 1980 to 2021, spanning 415 reserves (21.5 million ha) and 129 threatened species’ ranges including birds, mammals, reptiles, invertebrates, and frogs. Most reserves and threatened species’ ranges within the region have experienced declines in unburnt vegetation (≥30 y without fire), increases in recently burnt vegetation (≤5 y since fire), and increases in fire frequency. The mean percentage of unburnt vegetation within reserves declined from 61 to 36% (1980 to 2021), whereas the mean percentage of recently burnt vegetation increased from 20 to 35%, and mean fire frequency increased by 32%, with the latter two trends primarily driven by the record-breaking 2019 to 2020 fire season. The strongest changes occurred for high-elevation threatened species, and reserves of high elevation, high productivity, and strong rainfall decline, particularly in the southeast of the continent. Our results provide evidence for the widely held but poorly tested assumption that threatened species are experiencing widespread declines in unburnt habitat and increases in fire frequency. This underscores the imperative for developing management strategies that conserve fire-threatened species in an increasingly fiery future.
... Under these conditions, a tipping point can be reached due to the high costs of suppression strategies and the increased difficulties in dampening high-impact trajectories when these have an exponential growth 7,56,57 . In recent years, the recorded increase in megafires has already called for a paradigm shift to increase efforts toward mitigation rather than extinction measures 58,59 . Without mitigation, climate change is expected to increase the economic costs of fire suppression and may lead to fire seasons that overwhelm fire suppression agencies 60 . ...
This study quantifies how changes in temperature and precipitation would influence the intensity and duration of extreme fires across Europe. The analysis explores the impact of a range of climate change projections on fire events compared to a baseline of fire danger, using a 30-year ERA5 reanalysis. The results show that areas in southern Europe could experience a tenfold increase in the probability of catastrophic fires occurring in any given year under a moderate CMIP6 scenario. If global temperatures reach the +2 °C threshold, central and northern Europe will also become more susceptible to wildfires during droughts. The increased probability of fire extremes in a warming climate, in combination with an average one-week extension of the fire season across most countries, would put extra strain on Europe’s ability to cope in the forthcoming decades.
... All six studied species benefit from perturbations that limit vegetation encroachment and enhance landscape heterogeneity. The recovery of agricultural mosaics and extensive grazing, together with the implementation of programs of prescribed burning in certain areas, could strengthen the populations of the studied taxa, and could foment scarce habitats and contribute to reducing the risk and impact of future wildfires (Etienne 1996, Perevolotsky & Seligman 1998, Boer et al. 2009). We consider that the risk from wildfires will continue to increase in the Mediterranean basin in coming decades (Moriondo et al. 2006, Morán-Ordóñez et al. 2020) and so actions designed to reduce fuel continuity and vegetation encroachment -which also benefit threatened species -are appropriate management measures in terms of both fire prevention and biodiversity conservation (Castellnou et al. 2010). ...
... Nevertheless, humans have direct agency in decisions about when and where to exclude these actions and allow forest to grow to an older (and potentially less flammable) age. In south-western Western Australia, for example, 80% of area burned is by prescribed fire (Boer et al., 2009), and 80% of the remaining wildfire area results from human ignitions (Department of Biodiversity, Conservation and Attractions, 2021). This leaves only 4% of the burned area caused by natural ignitions, and 96% subject to human agency. ...
Many forest types globally have been subject to an increase in the frequency of, and area burnt by, high‐severity wildfire. Here we explore the role that previous disturbance has played in increasing the extent and severity of subsequent forest fires. We summarise evidence documenting and explaining the mechanisms underpinning a pulse of flammability that may follow disturbances such as fire, logging, clearing or windthrow (a process we term disturbance‐stimulated flammability). Disturbance sometimes initiates a short initial period of low flammability, but then drives an extended period of increased flammability as vegetation regrows. Our analysis initially focuses on well‐documented cases in Australia, but we also discuss where these pattens may apply elsewhere, including in the Northern Hemisphere. We outline the mechanisms by which disturbance drives flammability through disrupting the ecological controls that limit it in undisturbed forests. We then develop and test a conceptual model to aid prediction of woody vegetation communities where such patterns of disturbance‐stimulated flammability may occur. We discuss the interaction of ecological controls with climate change, which is driving larger and more severe fires. We also explore the current state of knowledge around the point where disturbed, fire‐prone stands are sufficiently widespread in landscapes that they may promote spatial contagion of high‐severity wildfire that overwhelms any reduction in fire spread offered by less‐flammable stands.
We discuss how land managers might deal with the major challenges that changes in landscape cover and altered fire regimes may have created. This is especially pertinent in landscapes now dominated by extensive areas of young forest regenerating after logging, regrowing following broadscale fire including prescribed burning, or regenerating following agricultural land abandonment.
Where disturbance is found to stimulate flammability, then key management actions should consider the long‐term benefits of: ( i ) limiting disturbance‐based management like logging or burning that creates young forests and triggers understorey development; ( ii ) protecting young forests from disturbances and assisting them to transition to an older, less‐flammable state; and ( iii ) reinforcing the fire‐inhibitory properties of older, less‐flammable stands through methods for rapid fire detection and suppression.
... In summary, our model simulations suggest that (i) that burning 10,000 and 20,000 ha/year across the landscape without spatial criteria (size and/or location), allowing the creation of open spaces and fuel discontinuity, and (ii) burning areas with medium to high fuel loads, i.e., areas that have not burned over a certain period of time, would mitigate the impact of future wildfires by around 21 to 36% by 2050 (scenarios 5 and 10%, respectively). These results align with other studies [66,67], indicating that fire hazard-oriented planning would increase the leverage from 0.18 to 0.32, particularly when the effort is low (see 0.5% scenarios in Table 3) [68]. In fact, the leverage values approximate to an overall value of 0.28 estimated for mainland Portugal [63]. ...
Integrating fire into land management is crucial in fire-prone regions. To evaluate the effectiveness and efficiency of prescribed fire (PF), we employed the REMAINS model in NW Iberia’s Transboundary Biosphere Reserve Gerês-Xurés. We tested three levels of prescribed fire treatment effort for shrubland and grassland, employing three spatial allocation strategies: random distribution, prioritization in high-wildfire-risk zones, and creating fuel breaks by utilizing the existing road network. These approaches were assessed in isolation and in combination with three land-use scenarios: Business-as-usual (representing rural abandonment trends), High Nature Value farmland (reversing farmland abandonment), and Fire-Smart forest management (promoting fire-resistant landscapes). Our results confirm that PF is effective in reducing future wildfires (reductions up to 36%), with leverage values ranging from 0.07 to 0.45. Strategic spatial allocation, targeting wildfire-risk areas and existing road networks, is essential for maximizing prescribed fire’s efficiency (leverage effort of 0.32 and 0.45; i.e., approximately 3 ha of PF decrease subsequent wildfire by 1 ha). However, the PF treatments yield the best efficiency when integrated into land-use policies promoting ‘fire-smart’ landscapes (reaching leverage values of up to 1.78 under policies promoting ‘HNVf and ‘fire-smart’ forest conversion). These recommendations strengthen wildfire prevention and enhance landscape resilience in fire-prone regions.
... Forest fire mainly occurs in mixed forest, deciduous forest, and forestry plantations (Royal Forest Department, n.d.), so it is necessary to build firebreaks in these areas and encourage cooperation with local people regarding forest burning to reduce the severity of forest fire and smoke caused by forest burning (Gnews, n.d.). In addition to data from land surveys, remote sensing technology can be used to evaluate burning forest areas (Boer et al., 2009;Mohammadi et al., 2014;Tariq et al., 2021a andTariq et al., 2021b). ...
... It has been documented that prescribed burning reduces fire intensity by minimizing fuel levels and disrupting the vertical and horizontal continuity of fuel in the landscape (Fernandes and Botelho 2003). The efficiency of this method in reducing the severity of wildfires has been supported by several studies (Boer et al. 2009). Furthermore, it has been noted that prescribed burning can accomplish other objectives, such as control of weeds, insects, and diseases; maintenance of biodiversity; site preparation for tree regeneration and enhancements of silvicultural practices (Savage et al. 2011). ...
Background Socio-economic changes of the last decades have led to fuel buildup in Mediterranean forests. In the context of Climate Change, this situation has resulted in the formation of potential fire traps that could lead to catastrophic events. Several wildfire management systems have therefore started to use prescribed fires for land management and wildfire risk mitigation. Prescribed fires are prepared by designing a plan, where specific objectives are identified, prescriptions are checked, and scenarios are defined. In the plan definition phase, simulation models can provide an additional decision-support tool, allowing the different scenarios to be qualitatively and quantitatively assessed. We used the well-established wildfire simulation tool PROPAGATOR to identify potential areas of treatment and to assess different scenarios of hypothetical prescribed fires. In the present work, we prepared the model for use in prescribed fires by changing the native space-time resolution to a finer scale. We selected a case study in the Liguria region, Italy, where the model is operationally used by the regional wildfire risk management system during emergencies. Results We first used the propagation model to simulate a wildfire event, to show the potentiality of the model as an emergency response tool. We selected the most important fire incident that occurred in the Liguria region in 2022. We then used PROPAGATOR to identify the optimal treatment areas to maximize wildfire risk mitigation effects and reduce the costs of treatment. In the identified areas, we used the model to simulate ignition scenarios in different weather conditions allowed by the regional regulation. The scenarios developed by the model made it possible to differentiate between situations that are under control and those that pose greater risks. Conclusions We showed how PROPAGATOR can provide quantitative and qualitative information that can be used in prescribed fire planning. Our methodology involved incorporating expert opinions throughout the process and providing scenarios based on this information. The possibility of evaluating different scenarios and having quantitative information helps make informed decisions, promoting safer and more efficient fire management practices.
... Treatments that include surface and ladder fuel removal were found to be consistently effective at reducing wildfire severity and increasing the chances of adult tree survival. Some of these studies are conducted using long-term data, such as Boer et al. (2009) who studied a 52-year fire history from the Eucalypt forest regions in southwestern Australia and found that a unit area reduction in wildfire requires about 4 unit areas of prescribed burning. In this study, the average annual extent of Rx over a period of 6 years explained a 24% variation in the average annual number and a 71% variation in the average annual extent of unintended wildfires. ...
In the current century, wildfires have shown an increasing trend, causing a huge amount of direct and indirect losses in society. Different methods and efforts have been employed to reduce the frequency and intensity of the damages, one of which is implementing prescribed fires. Previous works have established that prescribed fires are effective at reducing the damage caused by wildfires. However, the actual impact of prescribed fire programs is dependent on factors such as where and when prescribed fires are conducted. In this paper, we propose a novel data-driven model studying the impact of prescribed fire as a mitigation technique for wildfires to minimize the total costs and losses. This is applied to states in the USA to perform a comparative analysis of the impact of prescribed fires from 2003 to 2017 and to identify the optimal scale of the impactful prescribed fire programs using least-cost optimization. The fifty US states are classified into categories based on impact and risk levels. Measures that could be taken to improve different prescribed fire programs are discussed. Our results show that California and Oregon are the only severe-risk US states to conduct prescribed fire programs that are impactful at reducing wildfire risks, while other southeastern states such as Florida maintain fire-healthy ecosystems with very extensive prescribed fire programs. Our study suggests that states that have impactful prescribed fire programs (like California) should increase their scale of operation, while states that burn prescribed fires with no impact (like Nevada) should change the way prescribed burning is planned and conducted.
... Depending on the life-history traits of the vegetation, high severity fire may result in the short or long-term removal of overstorey shelter, so that succession and growth are more pronounced and the regrowth period more flammable than it would have been following a less-severe fire. Although no systematic data were available on the severity of fires that had affected our study area, more than 80% of previous fires in the bioregion had been prescribed burns rather than wildfire (Boer et al., 2009). Where our sites occurred in blocks that had recently been prescribed burnt, one site was high severity with complete crown scorch (site 1, Figure 2c), and the other had an intact canopy. ...
Forest wildfire impact is widely believed to increase with time since disturbance, presenting a dilemma for the persistence of fire‐sensitive species. However, in south‐western Australia, disturbance has been shown to increase wildfire likelihood for some decades before it again declines. It has been proposed that this trend occurs through ‘ecological controls’ on wildfire such as the self‐thinning of fire‐stimulated understorey growth.
Here, we analyse six proposed ecological controls using a surveyed chronosequence of a Eucalyptus jacksonii forest community. We quantify plant growth (growth and self‐pruning) and succession (changing plant traits, self‐thinning), along with consequent changes in surface and suspended litter. We then use a biophysical, mechanistic model to predict the dynamics of flame height and canopy scorch/consumption, along with suppression difficulty during wildfire conditions. To identify the importance of each potential ecological control, we separately manipulate them to grow hypothetical forests from 1 to 100 years; each with one of the controls removed. We then model flame height in each to compare with the original forest that had all controls present.
Fire initially promoted dense understorey regeneration, but ecological controls transferred this biomass from fuel (likely to ignite) to overstorey shelter (unlikely to ignite, creating a less flammable microclimate). The effect of these changes was to alter modelled fire behaviour, such that flame dimensions in mature forest were half those in regrowth, canopy damage greatly reduced, and fire suppression opportunities maximised. The primary controls were self‐thinning and self‐pruning.
Forest growth and succession explains observed trends in flammability dynamics in south‐western Australian forests, and the persistence of fire‐sensitive species over time. Approaches that cooperate with, rather than disrupt, these processes therefore provide a pathway to mitigate current climatic effects on fire.
Read the free Plain Language Summary for this article on the Journal blog.
... Hence, April to June can be optimal for interventions using fire, such as creating firebreaks and prescribed burning for management purposes, as during this period the risk of burning fertile plants is lower. Therefore, phenological information is relevant to conservation efforts and interventions that use prescribed fire as a form of adaptive management and a restoration tool (Boer et al., 2009;Bradshaw et al., 2018;Penman et al., 2011;Valentin-Silva et al., 2021). To decide when to apply fire, among other factors, indigenous peoples of the Brazilian savannas pay attention to the phenology of the plants they rely on. ...
The homogenization of fire regimes in a landscape may imply a temporal reduction in the availability of resources , such as flowers and fruits, which affect the fauna, as well as ecosystem services. We hypothesized that maintaining mosaic burning regimes, and thereby pyrodiversity, can diversify phenological patterns, ensuring year-round availability of flowers and fruits. Here we monitored open grassy tropical savanna phenology under different historical fire frequencies and fire seasons in a highly heterogeneous landscape in an Indigenous Territory in Brazil. We evaluated phenological patterns of tree and non-tree plants through monthly surveys over three years. These two life forms responded differently to climate and photoperiod variables and to fire. Different fire regimes led to a continuous availability of flowers and fruits, due to the complementarity between tree and non-tree phenologies. Late-season fires are supposed to be more devastating, but we did not detect a significant reduction in flower and fruit production, especially under moderate fire frequency. However, late burning in patches under high frequency resulted in a low availability of ripe fruits in trees. The fruiting of non-tree plants in patches under low fire frequency and early burning ensure ripe fruit, when there are practically no trees fruiting in the entire landscape. We conclude that maintaining a seasonal fire mosaic should be prioritized over historical fire regimes, which lead to homogenization. Fire management is best conducted between the end of the rainy season and the beginning of the dry season, when the risk of burning fertile plants is lower.
... However, increasing prescribed burning to these levels will come at an additional cost that may be high. In addition, in today's context in the South West forest region, this would be an exceptionally high level of prescribed burning and it may not be possible for several reasons: climate change (Bradstock et al. 2009;Cary et al. 2012; Barbero et al. 2015), the accumulation of fuels in the south-western forests of WA for the past 50 years (Boer et al. 2009), fire exclusion policies and the expansion of the WUI (Mutch et al. 2011), have all contributed to create a landscape in which the application of high rates of prescribed burning is increasingly difficult (Burrows and McCaw 2013;McCaw 2013). Nevertheless, this study emphasises the importance of keeping a minimum level of prescribed burning per year in the south-west forest region. ...
CITATIONS 2 READS 775 6 authors, including: Some of the authors of this publication are also working on these related projects: Relationship between soil and fuel drying-flammability switch in ash forests and damper foothill forests View project Managing bushfire in tall forests-fuel hazard and moisture relationships View project
... We are compelled to include the effects of all types of wildland fires. In Mediterranean ecosystems, and indeed worldwide, forms of management fires are used for land management to reduce fuel loads, in the hope that they might reduce the intensity and severity of wildland fires, and make them more controllable (see for example Boer et al. 2009 andDellaSalla et al. 2022). We therefore examine the literature to determine if such prescribed burns are also able to protect water quality in drinking water supply areas, in the context of DOM. ...
Fires in forested catchments pose a water contamination risk from fire-derived dissolved organic matter (DOM). Fire events are expected to increase under a projection of warmer and drier climatic conditions; therefore, understanding the consequences of fire-derived DOM is critical for water supply and management of drinking water and catchments. This paper addresses how fire regime - the intensity, severity and frequency of fires - influences DOM quantity and composition in surface waters in forested catchments, and how long it takes for water quality to recover to pre-fire levels. A review of post-fire studies in Mediterranean regions reporting on DOM related parameters has been conducted. The literature shows that post-fire DOM composition and reactivity is different from DOM generated under processes of biological degradation, and hence our reliance on DOM 'bulk properties' and surrogate DOM bulk parameters may not provide sufficient information to deal with the potential complexity of the organic compounds produced by a catchment fire. Appropriate measures are important to adequately operate conventional water treatment facilities, for example. Critical parameters for the effects of burning include the alteration of DOM composition, aromaticity, and the relative amounts of labile/recalcitrant organic components. The literature shows mixed information for the influence of both burn severity and fire intensity, on these parameters, which indicates DOM response to fire is highly variable. For fire frequency, the evidence is more unequivocal, indicating that frequent fires change the composition of DOM to components that are less bioavailable, and elevate the degree of aromaticity, which may be detrimental to water quality. In addition, and in general terms, the more recent the fire, the more aromatic and humified DOM components are found, and vice versa. The recovery of surface water quality to pre-fire conditions was variable, with no safe temporal thresholds suggested in the literature. In some cases, fire-induced changes in DOM composition were observable up to 16 years post-fire. The lack of clearly observed trends in post-fire DOM with fire regimes could be attributed to numerous factors such as limited long-term and event-based observations, experimental design challenges, and site-specific biological, physical and hydrological factors. The application of terminologies used to describe fire regimes such as burn severity and fire intensity also creates challenges in comparing the outcomes and results from numerous studies.
... The proportion was lowest in areas that had been burnt by prescribed burns since 2014, highest in areas burnt between 1999 and 2014, and intermediate in areas burnt between 1971 and 1999 or unburnt by prescribed burns since at least 1971 (Fig. 10). This is consistent with findings from other studies that a rapid fuel accumulation rate generally limits the effectiveness of prescribed burns in reducing fire hazard to a post-treatment period of 2-6 years (Raison et al. 1983, Fernandes and Botelho 2003, Boer et al. 2009). It is also consistent with indications that fire hazard reaches a peak in forests burnt 6-12 years previously and then declines to lower levels in long unburnt forests (Storey et al. 2016, Dixon et al. 2018. ...
The 2019-20 'Black Summer' mega-fires burnt an unprecedented 79% of the Greater Blue Mountains World Heritage Area, which is more than three times greater than the area burnt in any of the previous 48 fire seasons. The fires were not proportionally more severe than previous large fires but their huge scale meant that an unprecedented 29% of the World Heritage Area was burnt at high to extreme severity. The fires were particularly extensive and severe in parts of the World Heritage Area that are rarely burnt by wild-fires, notably in cooler areas over 1000 m in the southwest. The vegetation type least impacted by the fires was grassy woodland, an important bird habitat, of which 48% was burnt. However, grassy woodland covers less than 2% of the World Heritage Area and extensive areas of grassy woodland were burnt elsewhere in 2019-20. Rainforest and shrubby wet sclerophyll forest in sheltered gullies have played an important role in past fires as unburnt fauna refuges but were unusually heavily impacted in 2019-20, with 82% and 79% burnt, respectively. The fauna and flora of the World Heritage area are likely to eventually recover from the Black Summer fires if this was an exceptional event that will not recur for many decades. However, a change in the Australian fire regime to more frequent, more extensive, more severe wildfires as a result of climate change has long been predicted. If the Black Summer fires are a harbinger of this change, the long-term impact on the environment and biota of the World Heritage Area would be catastrophic.
... Prescribed burning involves reducing the fuel load in selected areas of the landscape. This reduces the spread and intensity of large wildfires (Boer et al., 2009;Coop et al., 2016;Lydersen et al., 2017), and thus the risk to human life and economic assets (Penman et al., 2011). ...
Hazard reduction is a complex task involving important efforts to prevent and mitigate the consequences of disasters. Many countries around the world have experienced devastating wildfires in recent decades and risk reduction strategies are now more important than ever. Reducing contiguous areas of high fuel load through prescribed burning is a fuel management strategy for reducing wildfire hazard. Unfortunately, this has an impact on the habitat of fauna and thus constrains a prescribed burning schedule which is also subject to uncertainty. To address this problem a mathematical programming model is proposed for scheduling prescribed burns on treatment units on a landscape over a planning horizon. The model takes into account the uncertainty related to the conditions for performing the scheduled prescribed burns as well as several criteria related to the safety and quality of the habitat. This multiobjective stochastic problem is modelled from a risk-averse perspective whose aim is to minimize the worst achievement of the criteria on the different scenarios considered. This model is applied to a real case study in Andalusia (Spain) comparing the solutions achieved with the risk-neutral solution provided by the simple weighted aggregated average. The results obtained show that our proposed approach outperforms the risk-neutral solution in worst cases without a significant loss of quality in the global set of scenarios.
... The Upper Warren region of south-western Australia includes 140 000 ha of publicly managed native vegetation (Wayne et al. 2013). It has a mediterranean climate, with warm summers, cool winters and mean annual rainfall of ~650-1000 mm (BoM 2020 (Boer et al. 2009). Most of the study area has been subject to one or more native timber harvesting events over the last 100 years, and although most land is now classified as either a Nature Reserve or National Park, about a third of the area is State Forest and remains available for timber harvesting until 2024 (Wayne et al. 2006). ...
Context
Invasive predators are major drivers of global biodiversity loss. Red foxes (Vulpes vulpes) and feral cats (Felis catus) have contributed to the decline and extinction of many native species in Australia. The deployment of poison baits to control fox populations is a widespread conservation tool, but the effects of baiting intensity, rainfall and prey abundance on baiting effectiveness remain poorly understood.
Aims
We aimed to understand what influences the association between fox baiting intensity, red fox activity and feral cat activity, to provide inferences about what might affect the effectiveness of fox baiting in reducing fox activity.
Methods
We used generalised linear models to assess how fox and cat activity changes in relation to fox baiting intensity, rainfall, native prey availability and distance to agricultural land over a 6-year period (2006–13) in the forest ecosystems of the Upper Warren region of south-western Australia.
Key results
We found that fox activity was negatively associated with rainfall in the previous 12 months and positively associated with prey abundance and fox baiting intensity. We also found an interaction between fox baiting and prey abundance, with fox activity increasing with prey activity in areas of low and moderate baiting intensity, but remaining constant in areas of high baiting intensity. Feral cat activity was positively associated with prey abundance and fox baiting intensity. We found no clear relationship between fox and cat activity.
Conclusions
The drivers of the association between fox baiting and fox activity are unclear because intense fox baiting was targeted at areas of known high fox abundance. However, our results indicate that intense fox baiting may be effective at decoupling the positive association between fox activity and prey abundance. Our results also suggest a positive association between fox baiting intensity and feral cat activity, thus supporting the case for integrated fox and cat management.
Implications
We caution interpretation of our results, but note that management of invasive predators could be improved by adjusting the intensity of management in response to changes in environmental conditions and local context (e.g. strategically conducting intense predator management where prey abundance is highest). Improved understanding of these associations requires a monitoring program with sufficient replication and statistical power to detect any treatment effects.
Unprecedented wildfires are expected to remain a major challenge for Europe in the coming years due to their increasing frequency and intensity. However, there is currently no standardized framework for managing wildfire risk, with no common definition of integrated wildfire risk management, and lack of consensus within sustainable forest management, with over 20 synonyms and semi-synonyms used for Continuous Cover Forestry (CCF), including among others, close-to-nature forest management. This open letter examines and highlights the importance of implementing two key approaches, the Integrated Fire Management (IFM) and the EU’s proposed approach of Closer-To-Nature Forest Management (CTNFM) with temporal and spatial connectivity in the face of climate change. The document discusses relevant management options to address wildfire risk challenges, and their associated impacts such as forest degradation and biodiversity loss. It emphasizes the urgent need for action by EU Member States in light of a bottom-up approach (local to regional and national level), political commitment, and public awareness to address these issues effectively. Key topics covered include wildfire adaptation strategies of plant species, and the impact of climate change and land use on today’s uncharacteristic fire regimes conditions. Silvicultural closer-to-nature practices, where needed and appropriate, such as the promotion of natural forest regeneration with enhancement of broadleaves, mixed stand composition and strategic tree spacing are examined as means to reduce the spread of fires in wildfire-prone areas. It also highlights the benefits of a landscape-scale approach to sustainable forest management that includes wildfire prevention, ecological resilience, habitat conservation and resource management. Options are presented for policy makers and relevant stakeholders to support these strategies through collaboration, enforcement, ecological stewardship, monitoring capabilities, public education, research support, and international cooperation. The integration of IFM and CTNFM can improve wildfire mitigation, preparedness, and adaptive capacity, thereby promoting resilient landscapes and communities in the long-term.
Prescribed fire is applied across the United States as a fuel treatment to manage the impact of wildfires and restore ecosystems. While the recent application of prescribed fire has largely been confined to the southeastern US, the increase in catastrophic wildfires has accelerated the growth of prescribed fire more broadly. To effectively achieve wildfire risk reduction benefits, which includes reducing the amount of smoke emitted, the area treated by prescribed fire must come into contact with a subsequent wildfire. In this study, we applied timely and consistent geospatially resolved data sets of prescribed fires and wildfires to estimate the rate at which an area treated by prescribed fire encounters a subsequent wildfire. We summarize these encounter rates across time intervals, prescribed fire treatment area, and number of previous prescribed fires and by region. On all U.S. Forest Service lands across the Conterminous US (CONUS) 6.2% of prescribed fire treated area from 2003–2022 encountered a subsequent wildfire in 2004–2023. Encounter rates were highest in western US forests, which tend to be more impacted by wildfire than the eastern US, and lower in the eastern US. Encounter rates increased with treatment area in the southeastern US but were relatively flat in the northwest. For the CONUS, encounter rates increased with longer time intervals, associated with diminished potential for reducing wildfire severity, between prescribed fire and the subsequent wildfire area burned. Our results provide timely information on prescribed fire and wildfire interactions that can be leveraged to optimize analyses of the trade-offs between prescribed fire and wildfire.
We report measurements of the absorption Ångström exponent (AAE) and single scattering albedo (SSA) of biomass burning aerosol from the combustion of fuel beds representing three eco-regions of the Southeast U.S. (Piedmont, Coastal Plain, and Blue Ridge Mountains) with moisture content representative of wildfires and prescribed fires. We find a strong correlation between the AAE and SSA for both simulated wildfires (low fuel moisture) and prescribed fires (higher fuel moisture). For wildfires, the AAE and SSA are strongly dependent on the eco-region of the fuel bed and span a much wider range (AAE = 1.3–4.2, SSA = 0.75–0.97) than they do for prescribed fires (AAE = 2.4–3.1, SSA = 0.88–0.96). The AAE and SSA are also found to be correlated with the fraction of total carbon that is elemental carbon (fEC) for both wildfires and prescribed fires, but the range of fEC observed (0.02–0.14) from the fuel beds is much smaller than that reported previously from laboratory studies using individual fuels. The observations from the present study suggest that fuel-bed composition and moisture content are significant factors in determining the relative amount of organic material in biomass burning aerosols and, consequentially, their optical properties.
Background
Socio-economic changes in recent decades have resulted in an accumulation of fuel within Mediterranean forests, creating conditions conducive to potential catastrophic wildfires intensified by climate change. Consequently, several wildfire management systems have integrated prescribed fires as a proactive strategy for land management and wildfire risk reduction. The preparation of prescribed fires involves meticulous planning, entailing the identification of specific objectives, verification of prescriptions, and the definition of various scenarios. During the planning phase, simulation models offer a valuable decision-support tool for the qualitative and quantitative assessment of different scenarios. In this study, we harnessed the capabilities of the well-established wildfire simulation tool , to identify areas where prescribed fires can be performed, optimizing the wildfire risk mitigation and the costs. We selected a case study in the Liguria region, Italy, where the model is utilized operationally by the regional wildfire risk management system in emergency situations.
Results
Initially, we employed the propagation model to simulate a historical wildfire event, showcasing its potential as an emergency response tool. We focused on the most significant fire incident that occurred in the Liguria region in 2022. Subsequently, we employed to identify optimal areas for prescribed fires with the dual objectives of maximizing the mitigation of wildfire risk and minimizing treatment costs. The delineation of potential areas for prescribed fires has been established in accordance with regional regulations and expert-based insights. The methodology put forth in this study is capable of discerning the most suitable areas for the implementation of prescribed burns from a preselected set. A Monte Carlo simulation framework was employed to evaluate the efficacy of prescribed burns in mitigating the spread of wildfires. This assessment accounted for a variety of conditions, including fuel loads, ignition points, and meteorological patterns. The model was utilized to simulate the progression of wildfire spread.
Conclusions
This study underscores the utility of in offering both quantitative and qualitative insights that can inform prescribed fire planning. Our methodology has been designed to involve active engagement with subject matter experts throughout the process, to develop scenarios grounded in their expert opinions. The ability to assess diverse scenarios and acquire quantitative information empowers decision-makers to make informed choices, thereby advancing safer and more efficient fire management practices.
Background
The Pinus yunnanensis forest in southwestern China is a unique and significant vegetation type. However, it is susceptible to frequent fires. To mitigate the risk of hazardous fires, prescribed burning has often been employed in these forests. Nevertheless, it is important to consider the potential impact of prescribed burning on the structure of plant communities and species diversity in Pinus yunnanensis forests. To investigate the specific changes in plant community characteristics of caused by prescribed burning, a study was conducted in the Pinus yunnanensis forest located in Zhaobi Hill, Xinping county.
Results
Prescribed burning has had minimal effects on canopy trees, but has partially altered the characteristics of the understory community. It has decreased the number of shrub species from 26 to 19, with a shift in dominance from saplings of Lithocarpus mairei and Pinus yunnanensis in the unburned area to Duhaldea cappa and Craibiodendron stellatum in the burned area. Additionally, prescribed burning has partially altered the abundance of species and reduced the average height of shrubs. Furthermore, prescribed burning has increased the number of herb species from 27 to 40, but has had minimal impact on their abundance, height, and importance value. It is worth noting that prescribed burning has different impacts on the species diversity of shrubs and herbs. It significantly decreases the α species diversity of shrubs, but only has minimal effects on the α species diversity indices of herbs. The β diversity indices indicate that the species composition in both burned and unburned areas is similar, but the impact of prescribed burning on shrubs is greater than on herbs. Overall, prescribed burning appears to be the primary factor affecting the species diversity index of shrubs, while altitude, forest structure, and soil nutrient content exert greater influences on the species diversity index of the herbaceous layer.
Conclusions
Prescribed burning had little impacts on overstory trees of the Pinus yunnanensis forest, it had slightly positive effects on the height of herbs, and increased species richness of herbs from 27 to 40. However, the effects of prescribed burning on the species diversity and the height of shrub layers were significant and negative. Prescribed burning was the dominant factor shaping the community structure and species diversity of the shrub layer, and the missing saplings of trees in shrub layers might influence future forest succession in a long time.
Background
The study of wildfire interactions (i.e., spread limitation and reburns) is gaining traction as a means of describing the self-limiting process of fire spread in the landscape and has important management implications but has not been attempted in Europe. We examined to what extent previously burned areas restricted the development of large wildfires (>500 ha) in mainland Portugal.
Results
We analysed wildfire areas in Portugal (1984-2021) and (1) modelled the proportion of large wildfire perimeters that ceased spread at fuel-age transitions to younger fuels resulting from previous wildfires, and (2) characterized patterns of large wildfire preference (and avoidance) for fuel age. Only 4% of the large wildfires did not comprise edges intersecting past wildfires. Low fuel age (especially up to 8 years post-fire) resulted in a high probability of a large wildfire perimeter being limited at fuel-age transitions, further enhanced by high historical burn probability and proximity to roads and watercourses. Perimeter limitation was lowest for Summer
wildfires (and high fire-suppression preparedness). The response of wildfire preference to increasing fuel age was extremely variable and thus an overall weak pattern emerged, with avoidance of fuels < 3 years and equal preference for ≥ 6-year-old fuels.
Conclusions
Large wildfire growth was hampered by building-up fuel resulting from antecedent wildfires. The fuel-reduction effect is short-lived in the prevailing Mediterranean humid climate of the study region. Nonetheless, it should be considered when planning fuel-reduction treatments and can be used as an opportunistic fuel treatment during large wildfire suppression operations.
Management of fire in the jarrah forest has advanced considerably since 1916 when the colonial forester Hutchins declared that “few Australians will admit that fire protection of the forest is practicable”. Since 1918, when the organised management of the jarrah forest commenced, Western Australia has advanced to become a recognised world leader in the control and management of forest fire. The scope of fire management has progressively expanded in order to accommodate the increasingly complex demands placed on forests by society. Initial concerns for the protection of human life and private property soon expanded to include protection of the forest timber resource. Nowadays, forest fire managers are increasingly being called upon to integrate fire with a wide range of activities including recreation, fauna conservation and maintenance of landscape amenity. Fire management practices must also be modified to accommodate the major changes in the structure and species composition of some areas of forest as a result of human activities such as logging and mining.
The many ways that people have used and managed land throughout history has emerged as a primary cause of land-cover change around the world. Thus, land use and land management increasingly represent a fundamental source of change in the global environment. Despite their global importance, however, many decisions about the management and use of land are made with scant attention to ecological impacts. Thus, ecologists' knowledge of the functioning of Earth's ecosystems is needed to broaden the scientific basis of decisions on land use and management. In response to this need, the Ecological Society of America established a committee to examine the ways that land-use decisions are made and the ways that ecologists could help inform those decisions. This paper reports the scientific findings of that committee. Five principles of ecological science have particular implications for land use and can assure that fundamental processes of Earth's ecosystems are sustained. These ecological principles deal with time, species, place, disturbance, and the landscape. The recognition that ecological processes occur within a temporal setting and change over time is fundamental to analyzing the effects of land use. In addition, individual species and networks of interacting species have strong and far-reaching effects on ecological processes. Furthermore, each site or region has a unique set of organisms and abiotic conditions influencing and constraining ecological processes, Disturbances are important and ubiquitous ecological events whose effects may strongly influence population, community, and ecosystem dynamics. Finally, the size, shape, and spatial relationships of habitat patches on the landscape affect the structure and function of ecosystems. The responses of the land to changes in use and management by people depend on expressions of these fundamental principles in nature. These principles dictate several guidelines for land use. The guidelines give practical rules of thumb for incorporating ecological principles into land-use decision making. These guidelines suggest that land managers should: (1) examine impacts of local decisions in a regional context, (2) plan for long-term change and unexpected events, (3) preserve rare landscape elements and associated species, (4) avoid land uses that deplete natural resources, (5) retain large contiguous or connected areas that contain critical habitats, (6) minimize the introduction and spread of nonnative species, (7) avoid or compensate for the effects of development on ecological processes, and (8) implement land-use and management practices that are compatible with the natural potential of the area. Decision makers and citizens are encouraged to consider these guidelines and to include ecological perspectives in choices on how land is used and managed. The guidelines suggest actions required to develop the science needed by land managers.
Fire frequencies before and after European settlement were compared by studying stem sections from large, old jarrah (Eucalyptus marginata)trees for fire injury and by relating this to the documented historical evidence. The resilience of jarrah to injury by fire and the limitations of ring counting as an ageing technique, prevented an accurate and definitive reconstruction of the fire frequency prior to European settlement. However, the chronological pattern of fire-caused bole injury supports historical descriptions of fire history and can be explained by broad eras of human activity in the forest. Prior to European settlement, the incidence of fire injury was very low with the average interval between injurious fires being about 81 years. Following European settlement, the frequency of fire injuries increased and the average interval between injuries decreased to about 17 years. The pre-European fire regime in the drier jarrah forest and the forest margin was probably one of frequent, non-injurious, low intensity fires set mainly in summer and autumn, with occasional long intervals between fires ending in high intensity, injurious fires. The increase in fire injury to trees immediately following European settlement and up to the 1950s is probably due to the higher frequency of intense wildfires associated with increased fuel levels resulting from logging and long periods of fire exclusion.
In many landscapes, an important fire management objective is to reduce the negative impacts from unplanned fires on people, property and ecological values. In Australia, there exists an inherent assumption that high spatial variability in fire ages and hence fuel loads will have negative effects on both the incidence and spread of subsequent fires, and will enhance ecological values. A recent study using the process-based computer simulation model FIRESCAPE-SWTAS predicted several relationships between prescribed burn treatment levels and spatial patterning and management objectives in south-west Tasmania, Australia. The present study extended this investigation to additionally explore the effects of prescribed burning treatment unit size on unplanned fire incidence and area burned both in the general landscape and specifically in fire-intolerant vegetation. Simulation results suggest that treatment level had the greatest influence on modifying fire effects, whereas treatment unit size had the least effect. The model predicted that all three parameters interacted to determine the mean annual area burnt by unplanned fires. In fire-intolerant vegetation, treatment unit size did not influence the incidence of unplanned fires and the area burnt by unplanned fires in these communities. Where significant differences were evident, fire risk was reduced by higher treatment levels, deterministic spatial patterns of burning units, and smaller burning unit sizes.
Computer simulation modelling provides a useful approach for determining the trade-offs between the extent of prescribed burning and the long-term impacts of unplanned fires on management values. In the present study, FIRESCAPE-SWTAS, a process-based fire regime and vegetation dynamics model, was used in the World Heritage Area of south-west Tasmania, Australia, to investigate the implications of different prescribed burning treatments on identified management objectives. Treatments included annual prescribed burning of different proportions of the most flammable vegetation community, buttongrass moorlands. Additionally, a proposed strategic burning treatment for this landscape was simulated for comparison with these treatments. Simulations identified the nature of the relationships between the prescribed burn treatment level and the fire size distributions, the mean incidence, and the mean annual areas burnt by unplanned fires, with all three parameters declining with increases in treatment level. The study also indicated that strategically located treatment units were able to enhance the reduction in the fire risk to vegetation species susceptible to fire (fire-intolerant species).
Over the last seven decades, the Mediterranean-type shrublands of the Swartberg Mountain Range (170 856 ha), South Africa, have been subject to divergent fire management policies. Management objectives sequentially focused on grazing, fire control, water and biodiversity conservation during successive fire management periods. The aim of the present study was to explore the factors that determined the prevailing fire regime patterns during these fire management periods. This was considered particularly relevant in view of the ongoing debate on the relative role of fuel characteristics versus weather and ignition rates in shaping fire regime patterns. The extent of burning followed climatic cycles of alternating periods of relatively high temperatures and summer rainfall with cooler periods and increased winter rainfall. Accordingly, fires occurred more extensively during the former and were largely unaffected by the absence or presence of fire control measures. Fire return intervals were strongly inversely related to productivity of the vegetation. Long-term means between 30 and 55 years were found to apply in low-altitude xeric shrubland types. Corresponding fire return intervals were generally shorter in mesic shrublands at mid to high altitudes (15–30 years). Proteoid shrublands younger than 6 years were practically non-flammable. Two basic fire regime scenarios were identified. Fire regime patterns in xeric shrublands at lower altitudes were largely controlled by the rate of fuel accumulation, whereas climatically controlled ignition frequencies and fire climate constituted the dominant controls in proteoid shrublands at mid to high altitudes. The spatiotemporal distribution of fire regime parameters (fire frequencies, season, size and intensity) as recorded in the present study for the Swartberg Mountain Range under natural fire zone management (predominance of lightning fires since 1980), appeared to be conducive to the maintenance of biodiversity according to our current understanding of the fire–vegetation system.
Records of the annual area burnt by prescribed fire and wildfire extending back to 1937 are available for much of the publicly-owned forest in the south-west of Western Australia. These records exist in the form of maps prepared at local forest divisional (later district) offices from first-hand knowledge of the extent of prescribed burning activities and wildfires. Original maps have subsequently been incorporated into a Geographic Information System providing a unique insight into regimes of fire frequency and seasonality at a landscape scale over more than half a century. In this paper we examine ways in which fire history information can provide a con- text for contemporary management decisions about the use of fire for fuel reduction, and the effects of fire on forest ecosystems. More detailed records of the patchiness of burn patterns within pre- scribed burns and wildfires would assist in understanding the effects of fire at a landscape scale.
The current paper analyses the potential for prescribed burning techniques for mitigating carbon dioxide (CO2) emissions from forest fires and attempts to show quantitatively that it can be a means of achieving a net reduction of carbon emissions in the context of the Kyoto Protocol. The limited number of available studies suggests that significant reductions in CO2 emissions can be obtained and that prescribed burning can be a viable option for mitigating emissions in fire-prone countries. The present analysis shows that the potential reduction attained by prescribed burning as a percentage of the reduction in emissions required by the Kyoto Protocol varies from country to country. Out of the 33 European countries investigated, only in one the requirements of the Kyoto Protocol could potentially be achieved by applying prescribed burning, while three other nations showed a potential net CO2 emissions reduction of about 4–8% of the Kyoto requirements and the majority showed a reduction of less than 2%. This implies that prescribed burning can only make a significant contribution in those countries with high wildland fire occurrence. Over a 5-year period the emissions from wildfires in the European region were estimated to be approximately 11 million tonnes of CO2 per year, while with prescribed burning application this was estimated to be 6 million tonnes, a potential reduction of almost 50%. This means that for countries in the Mediterranean region it may be worthwhile to account for the reduction in emissions obtained when such techniques are applied.
The 2007 wildfire season in southern California burned over 1,000,000 ac (∼400,000 ha) and included several megafires. We use the 2007 fires as a case study to draw three major lessons about wildfires and wildfire complexity in southern California. First, the great majority of large fires in southern California occur in the autumn under the influence of Santa Ana windstorms. These fires also cost the most to contain and cause the most damage to life and property, and the October 2007 fires were no exception because thousands of homes were lost and seven people were killed. Being pushed by wind gusts over 100 kph, young fuels presented little barrier to their spread as the 2007 fires reburned considerable portions of the area burned in the historic 2003 fire season. Adding to the size of these fires was the historic 2006-2007 drought that contributed to high dead fuel loads and long distance spotting. As in 2003, young chaparral stands and fuel treatments were not reliable barriers to fire in October 2007. Second, the Zaca Fire in July and August 2007 showed that other factors besides high winds can sometimes combine to create conditions for large fires in southern California. Spring and summer fires in southern California chaparral are usually easily contained because of higher fuel moisture and the general lack of high winds. However, the Zaca Fire burned in a remote wilderness area of rugged terrain that made access difficult. In addition, because of its remoteness, anthropogenic ignitions have been low and stand age and fuel loads were high. Coupled with this was severe drought that year that generated fuel moisture levels considerably below normal for early summer. A third lesson comes from 2007 conifer forest fires in the southern California mountains. In contrast to lower elevation chaparral, fire suppression has led to major increases in conifer forest fuels that can lead to unnaturally severe fires when ignitions escape control. The Slide and Grass Valley Fires of October 2007 occurred in forests that had been subject to extensive fuel treatment, but fire control was complicated by a patchwork of untreated private properties and mountain homes built of highly flammable materials. In a fashion reminiscent of other recent destructive conifer fires in California, burning homes themselves were a major source of fire spread. These lessons suggest that the most important advances in fire safety in this region are to come from advances in fire prevention, fire preparedness, and land-use planning that includes fire hazard patterns.
Evolutionary and paleoecological studies suggest that fires are natural in the Mediterranean basin. However, the important increase in the number of fires and area burned during the 20th century has created the perception that fires are disasters. In the present paper, we review to what extent fires are generating ecological disasters in the Mediterranean basin, in view of current fire regimes and the long-term human pressure on the landscapes. Specifically, we review studies on post-fire plant regeneration and soil losses. The review suggests that although many Mediterranean ecosystems are highly resilient to fire (shrublands and oak forest), some are fire-sensitive (e.g. pine woodlands). Observed erosion rates are, in some cases, relatively high, especially in high fire severity conditions. The sensitive ecosystems (in the sense of showing strong post-fire vegetation changes and soil losses) are mostly of human origin (e.g. extensive pine plantations in old fields). Thus, although many Mediterranean basin plants have traits to cope with fire, a large number of the ecosystems currently found in this region are strongly altered, and may suffer disasters. Post-fire disasters are not the rule, but they may be important under conditions of previous human disturbances.
A simulation system was developed to explore how fuel treatments placed in topologically random and optimal spatial patterns affect the growth and behaviour of large fires when implemented at different rates over the course of five decades. The system consisted of a forest and fuel dynamics simulation module (Forest Vegetation Simulator, FVS), logic for deriving fuel model dynamics from FVS output, a spatial fuel treatment optimisation program, and a spatial fire growth and behaviour model to evaluate the performance of the treatments in modifying large fire growth. Simulations were performed for three study areas: Sanders County in western Montana, the Stanislaus National Forest in California, and the Blue Mountains in south-eastern Washington. For different spatial treatment strategies, the results illustrated that the rate of fuel treatment (percentage of land area treated per decade) competes against the rates of fuel recovery to determine how fuel treatments contribute to multidecade cumulative impacts on the response variables. Using fuel treatment prescriptions that simulate thinning and prescribed burning, fuel treatment arrangements that are optimal in disrupting the growth of large fires require at least 1 to 2% of the landscape to be treated each year. Randomly arranged units with the same treatment prescriptions require about twice that rate to produce the same fire growth reduction. The results also show that the topological fuel treatment optimisation tends to balance maintenance of previous units with treatment of new units. For example, with 2% landscape treatment annually, fewer than 5% of the units received three or more treatments in five decades with most being treated only once or twice and ~35% remaining untreated after five decades.
Power law frequency-size distributions of forest fires have been observed in a range of environments. The scaling behaviour
of fires, and more generally of landscape patterns related to recurring disturbance and recovery, have previously been explained
in the frameworks of self-organized criticality (SOC) and highly optimized tolerance (HOT). In these frameworks the scaling
behaviour of the fires is the global structure that either emerges spontaneously from locally operating processes (SOC) or
is the product of a tuning process aimed at optimizing the trade-offs between system yield and tolerance to risks (HOT). Here,
we argue that the dominant role of self-organized or optimised fuel patterns in constraining unplanned-fire sizes, implicit
in the SOC and HOT frameworks, fails to recognise the strong exogenous controls of fire spread (i.e. by weather, terrain,
and suppression) observed in many fire-prone landscapes. Using data from southern Australia we demonstrate that forest fire
areas and the magnitudes of corresponding weather events have distributions with closely matching scaling exponents. We conclude
that the spatial scale invariance of forest fires may also be a mapping of the meteorological forcing pattern.
Management of forests for carbon uptake is an important tool in the effort to slow the increase in atmospheric CO2 and global warming. However, some current policies governing forest carbon credits actually promote avoidable CO2 release and punish actions that would increase long-term carbon storage. In fire-prone forests, management that reduces the risk of catastrophic carbon release resulting from stand-replacing wildfire is considered to be a CO2 source, according to current accounting practices, even though such management may actually increase long-term carbon storage. Examining four of the largest wildfires in the US in 2002, we found that, for forest land that experienced catastrophic stand-replacing fire, prior thinning would have reduced CO2 release from live tree biomass by as much as 98%. Altering carbon accounting practices for forests that have historically experienced frequent, low-severity fire could provide an incentive for forest managers to reduce the risk of catastrophic fire and associated large carbon release events.
Wildfire hazard abatement is one of the major reasons to use prescribed burning. Computer simulation, case studies, and analysis of the fire regime in the presence of active prescribed burning programs in forest and shrubland generally indicate that this fuel management tool facilitates fire suppression efforts by reducing the intensity, size and damage of wildfires. However, the conclusions that can be drawn from the above approaches are limited, highlighting the need for more properly designed experiments addressing this question. Fuel accumulation rate frequently limits prescribed fire effectiveness to a short post-treatment period (2–4 years). Optimisation of the spatial pattern of fire application is critical but has been poorly addressed by research, and practical management guidelines are lacking to initiate this. Furthermore, adequate treatment efforts in terms of fire protection are constrained by operational, social and ecological issues. The best results of prescribed fire application are likely to be attained in heterogeneous landscapes and in climates where the likelihood of extreme weather conditions is low. Conclusive statements concerning the hazard-reduction potential of prescribed fire are not easily generalised, and will ultimately depend on the overall efficiency of the entire fire management process.
Significant climatic changes over Northern Eurasia during the 20th century have been reflected in numerous variables of economic, social, and ecological interest, including the natural frequency of forest fires. For the former USSR, we are now using the Global Daily Climatology Network and a new Global Synoptic Data Network archive, GSDN, created jointly by U.S. National Climatic Data Center and Russian Research Institute for Hydrometeorological Information. Data from these archives (approximately 1500 of them having sufficiently long meteorological time series suitable for participation in our analyses) are employed to estimate systematic changes in indices used in the United States and Russia to assess potential forest fire danger. We use four indices: (1) Keetch–Byram Drought Index, (KBDI; this index was developed and widely used in the United States); (2) Nesterov, (3) Modified Nesterov, and (4) Zhdanko Indices (these indices were developed and widely used in Russia). Analyses show that after calibration, time series of the days with increased potential forest fire danger constructed using each of these three indices (a) are well correlated and (b) deliver similar conclusions about systematic changes in the weather conditions conducive to forest fires. Specifically, over the Eastern half of Northern Eurasia (Siberia and the Russian Far East) statistically significant increases in indices that characterize the weather conditions conducive to forest fires were found. These areas coincide with the areas of most significant warming during the past several decades south of the Arctic Circle. West of the Ural Mountains, the same indices show a steady decrease in the frequency of “dry weather summer days” during the past 60 yr. This study is corroborated with available statistics of forest fires and with observed changes in drought statistics in agricultural regions of Northern Eurasia.
Fire spreads in a specifically spatial manner, which suggests the applicability of percolation models to the risk reduction problem. It is shown that under fairly general conditions a threshold exists below which a landscape becomes essentially fireproof. Arranging treated acres into a grid, analogous to bulkheads on a ship, drastically reduces the acreage that must be treated to achieve a fireproof condition. Such compartmentation of the landscape yields a much higher leverage (ratio of acres saved to acres treated). Certain landscape features create updrafts that spread fire particularly far. Treating fuels in such areas yields high leverage. Fire shadow effects were replicated by the simulation and showed a possible mechanism for amplifying treatment effectiveness. Either fuel reduction programs or commercial forestry can be used to achieve hazard reduction without excessive costs if spatial aspects of fire spread are taken into account.
Successful fire exclusion in the 20th century has created severe fire problems across the West. Not every forest is at risk of uncharacteristically severe wildfire, but drier forests are in need of active management to mitigate fire hazard. We summarize a set of simple principles important to address in fuel reduction treatments: reduction of surface fuels, increasing the height to live crown, decreasing crown density, and retaining large trees of fire-resistant species. Thinning and prescribed fire can be useful tools to achieve these objectives. Low thinning will be more effective than crown or selection thinning, and management of surface fuels will increase the likelihood that the stand will survive a wildfire. Five empirical examples of such treatment are discussed: Hayfork fires, California, 1987; Tyee fire, Washington, 1994; Megram fire, California, 1999; Hayman fire, Colorado, 2002; and the Cone fire, California, 2002. Applying treatments at an appropriate landscape scale will be critical to the success of fuel reduction treatments in reducing wildfire losses in Western forests.
The behaviour of five landscape fire models (CAFÉ, FIRESCAPE, LAMOS(HS), LANDSUM and SEM-LAND) was compared in a standardised modelling experiment. The importance of fuel management approach, fuel management effort, ignition management effort and weather in determining variation in area burned and number of edge pixels burned (a measure of potential impact on assets adjacent to fire-prone landscapes) was quantified for a standardised modelling landscape. Importance was measured as the proportion of variation in area or edge pixels burned explained by each factor and all interactions among them. Weather and ignition management were consistently more important for explaining variation in area burned than fuel management approach and effort, which were found to be statistically unimportant. For the number of edge pixels burned, weather and ignition management were generally more important than fuel management approach and effort. Increased ignition management effort resulted in decreased area burned in all models and decreased number of edge pixels burned in three models. The findings demonstrate that year-to-year variation in weather and the success of ignition management consistently prevail over the effects of fuel management on area burned in a range of modelled ecosystems.
Effective decision‐making in environmental management requires the consideration of multiple objectives that may conflict. Common optimization methods use weights on the multiple objectives to aggregate them into a single value, neglecting valuable insight into the relationships among the objectives in the management problem.
We present a multi‐objective optimization procedure that approximates the non‐dominated Pareto frontier without the use of weightings, allowing for visualization of the trade‐offs among objectives. The non‐dominated Pareto frontier is approximated by the simultaneous optimization of a vector objective function; two vector objective functions are defined as non‐dominated if improvement with respect to one objective is at the detriment of another objective.
We demonstrate the method with a case study for the optimum distribution of forest fuels treatments that reduce the impact of fire on a forest. The multiple objectives are to protect habitat of an endangered species, protect late successional forest reserves and minimize the total area treated. In the comparison of three optimization searches, the number of non‐dominated solutions increases with the dimensions of the objective space, but with only two objectives the search is ineffective in minimizing fire impact in the different landscape types. Key challenges include the extensive computation time required to approximate the non‐dominated set, and reducing the number of solutions that are analysed in detail.
Synthesis and applications . The multi‐objective optimization program presented can be adapted to other environmental management problems, and easily incorporates a wide range of quantifiable objectives. This tool provides decision‐makers with a set of alternatives that estimates the full range of trade‐offs among multiple objectives and provides a common ground from which dialogue can come to an informed compromise and decision in environmental management problems.
The first edition of this book has established itself as one of the leading references on generalized additive models (GAMs), and the only book on the topic to be introductory in nature with a wealth of practical examples and software implementation. It is self-contained, providing the necessary background in linear models, linear mixed models, and generalized linear models (GLMs), before presenting a balanced treatment of the theory and applications of GAMs and related models. The author bases his approach on a framework of penalized regression splines, and while firmly focused on the practical aspects of GAMs, discussions include fairly full explanations of the theory underlying the methods. Use of R software helps explain the theory and illustrates the practical application of the methodology. Each chapter contains an extensive set of exercises, with solutions in an appendix or in the book’s R data package gamair, to enable use as a course text or for self-study.
Land management in fire-prone regions must consider the impacts of fire on organisms, habitats and human societies. Maintenance of accurate fire records is an essential tool to enable managers to consider these impacts. Forests in southwestern Australia have a long history of prescribed burning for a variety of land management objectives. Records of fire occurrence for prescribed burns and wildfires have been maintained since 1937 as microfiche images of paper maps. In this paper, we describe the process used to convert these old maps, as well as more recent spatial data, into one spatial database contained within a Geographic Information System. This methodology has broad interest to those who maintain similar spatial information. This fire history database (FHD) contains both spatial and non- spatial (descriptive) information on prescribed burns and wildfires, including perimeter, area, season-of-burn and ignition method. The FHD allows spatial and temporal analysis of fire history, and we present some regional trends of fire history for the Warren Region. Prescribed burns dominate the fire history, though the occurrence of large wildfires in 2003 significantly influences the fuel age distribution. In this paper, we describe the functionality and limitations of the dataset, and discuss improvements that can be made to current and future data collection.
A fire history was derived for the Cederberg State Forest (Cape Province, South Africa) for the period 1956–1986. Fire frequency was determined by analysing the distribution of fire-free intervals observed at grid intersections superimposed on the mapped fires. The overall frequency was estimated at 11–15 years. Topography had little effect on frequency. The natural fire season was defined as November–February, and to a lesser extent March and April. Fifty-eight wildfires burnt 78 000 ha in the period of observation. The effects of a policy of prescribed burning (introduced in 1973) on the extent and frequency of wildfires are not yet evident. The policy of prescribed burning in late summer and early autumn is vindicated on the basis of positive vegetation response to fires in these months. Concern is expressed at the ecological effects of prescribed burns not being carried out in the natural fire season, which may result in the local extinction of some plant species.
INTRODUCTION Fuel reduction burning (FRB) has been practised on a broadscale in Victoria for nearly 30 years. FRB involves the deliberate use of fire, under prescribed (or pre-determined) weather and fuel moisture conditions (generally in the autumn), to reduce both the amount, and vertical extent, of forest fuels, including surface litter, bark and understorey shrubs. FRB or "burning off", as it is more commonly known, is carried out reduce these fuel hazards, and thereby assist with the control of wildfires in later years. On average approximately 100,000 hectares, out of a total of 7.8 million hectares, of public land is burnt in the fuel reduction burning program each year. The Department of Sustainability and Environment (DSE) has most of the responsibility for fuel reduction burning on public land, due to its obligations for hazard reduction under the Forests Act 1958. The majority of the area burnt is in areas identified in Fire Protection Plans as being of strategic importance. The Code of Practice for Fire Management on Public Land identifies five Fuel Management Zones (FMZs), with Zone 1 having the aim to protect life, property and assets, and therefore being of primary importance for fuel hazards to be kept at their lowest possible levels. Zones 2, 3 and 4 are then seen as being of decreasing importance, except that Zone 2 is intended to provide long strategic "strips" of fuel reduced area which can act as a barrier to large fast-moving wildfires. Zone 5 is not intended to be prescribed burnt. Although a number of Victorian studies had looked at the effectiveness of fuel reduction burning in specific instances (Billing 1981, Rawson, Billing and Rees 1985, Grant and Wouters 1993) there had not been a broad evaluation of the effectiveness of the Statewide fuel reduction burning program.
South-west Australia is a region of remarkable biological diversity, predominantly shaped by diversity of climate and geomorphology. Fire has also played an important role in shaping biodiversity over at least 2.5 million years and anthropogenic fire has been a part of this environment for tens of thousands of years. Forest ecosystems are fire-maintained, having evolved traits that enable them to persist with, and depend upon a variety of fire regimes. No single regime is optimal for all organisms and communities, but diverse regimes, within ecological limits, are essential for maintaining biodiversity. Bushfires can also threaten people, property and industry so fire management, including proactive use of fire, is necessary to both conserve biodiversity and to reduce the negative impacts of bushfires. There exists a substantial body of fire ecology literature for these ecosystems. If on-ground fire management is to advance commensurate with advances in fire science, then this often complex plethora of information needs to be synthesized, simplified and presented as practical fire management paradigms, policies and prescriptions. This paper attempts to achieve this by describing a range of evidence-based practical fire regimes that can be implemented to conserve biodiversity and to protect human life and property in south-west Australian forests.
This report describes a program, FRAGSTATS, developed to quantify landscape structure. Two separate versions of FRAGSTATS exist: one for vector images and one for raster images. In this report, each metric calculated by GRAGSTATS is described in terms of its ecological application and limitations. Example landscapes are included, and a discussion is provided of each metric as it relates to the sample landscapes. -from Authors
