International Journal of Wildland Fire最新文献

Predicting fire behaviour is an ongoing challenge in temperate peatlands and heathlands, where live fuels can form the dominant fuel load for wildfire spread, and where spatial heterogeneity in fuel moisture is important but not typically represented in fuel models.

We examine the impact of fuel moisture variation on simulated fire behaviour across a temperate peatland/heathland landscape.

We collected field measurements of fuel moisture content in Calluna vulgaris shrub from 36 sites across the North Yorkshire Moors, United Kingdom. We used these to define fuel moisture inputs within existing shrubland fuel models to simulate fire behaviour in BehavePlus.

Simulated rates of spread varied with fuel moisture content; average mean variance of 23–80% from the landscape average rate of spread. The driest sites had simulated rates of spread up to 135% above the landscape average and the wettest sites up to 86% below average. Fuel model selection dramatically impacted simulated rates of spread by a factor of five.

We need to constrain the role of live fuel moisture within temperate fuel models to develop accurate fire behaviour predictions.

Capturing cross-landscape heterogeneity in fire behaviour is important for safe and effective land and wildfire management decision-making.

We use case studies to explore the impact of changed fire regimes on vegetation structure and fuel risk in Southeast Queensland, Australia. Multiple studies report high intensity wildfires promote excessive shrub and sapling densities, which increase elevated fuel hazard. We argue asset protection burns in dry conditions can cause similar vegetation thickening to an intense wildfire, which increases fire severity risk due to increased elevated fuel loads. We demonstrate regular low intensity burning with adequate soil moisture can achieve fuel reduction objectives. This provides a longer-term solution that promotes risk reduction to communities, whilst leading to better ecological outcomes and reduced cost of implementation over the long-term.

As fire regimes continue to evolve in response to climate change, understanding how fire characteristics have responded to changes in the recent past is vital to inform predictions of future fire events.

Using Fourier Transform Infrared (FTIR) spectroscopy, we assessed how fire intensity has changed in two fire-prone landscapes in south-eastern Australia: (1) the Blue Mountains; and (2) Namadgi National Park during the past 3000 years.

Higher aromatic/aliphatic ratios suggest increased high-intensity fire frequency in sediments at the surface of both cores. Increases in the frequency of extreme drought periods, coupled with the change in vegetation and anthropogenic ignitions following colonisation, could have increased the frequency of high-intensity fires in the past ~200 years.

FTIR spectroscopy can be used in sediment deposits to infer that the frequency of high-intensity fire events has increased in the past 200 years compared to the previous ~3000 years.

These results are important for understanding how past fire regimes have responded to climate, people and vegetation shifts in the past ~3000 years and can be used to inform models for future predictions and management strategies.

Fires release large pulses of nitrogen (N), which can be taken up by recovering plants and microbes or exported to streams where it can threaten water quality.

The amount of N exported depends on the balance between N mineralisation and rates of N uptake after fire. Burn severity and soil moisture interact to drive these rates, but their effects can be difficult to predict.

To understand how soil moisture and burn severity influence post-fire N cycling and retention in a dryland watershed, we quantified changes in plant biomass, plant N content, soil microbial biomass, inorganic N pools, and net N mineralisation for 2 years after fire. We compared sites that were unburned with those that burned at moderate or high severity, capturing variation in soil moisture within each severity category.

Severe fire limited N uptake by plants. Dry conditions after fire limited both plant and microbial N uptake.

When fire is severe or when soils are relatively dry after fire, recovering plants and microbes are less likely to take up post-fire N and therefore, N in these sites is more susceptible to export.

Wildfire propagation is inherently non-steady, although forecasts of their spread focus on a pseudo-steady state assumption.

To investigate the variability in rate of fire spread of wildfires in southern Australian grassland landscapes, and the effect of landscape features in inhibiting fire propagation. To evaluate the adequacy of grassfire rate of spread models currently used in Australia.

We reconstructed the propagation of six wildfires in grassland fuels and characterised the unsteady nature of rate of spread. We also analysed the effect of barriers to fire spread in slowing or halting wildfire propagation.

Headfire rate of spread in wildfires was observed to be non-steady, with peaks in forward rate of spread being on average 2.6-times higher than mean values. The rate of spread had an average coefficient of variation of 88%. Areas of fuel discontinuity, such as roads, did not stop fires under moderate burning conditions, but resulted in slowing the average rate of fire spread.

Analysis of wildfire observations is key to understand fire behaviour features that are not replicable in experimental or modelling environments. Findings from the analysis can support fire-fighting safety awareness and inform landscape fire propagation modelling.

Balanggarra, Dambimangari, Wilinggin and Wunambal Gaambera Traditional Owners in Western Australia operate Savanna Fire Management projects under the collective North Kimberley Fire Abatement Project.

We examine changes to the fire regime before and after the initiation of these projects and discuss implications for incentivising savanna fire management.

Using established methods and high-resolution imagery, we compared fire metrics between baseline (2001–2011) and project years (2012–2022).

Fire seasonality notably shifted from late to early dry season dominance with fewer late season fires across, resulting in carbon abatement. While total area burnt remained similar, annual fire pattern transitioned from a cyclical to less variable regime. Fire patchiness, fire age diversity, and area of long unburnt vegetation increased while fire frequency decreased. A minimum of 4 years of fire management was required before significant changes in fire metrics were observed.

The fire regime on Traditional Owner lands has improved significantly, enabled by the emergence of land and sea management, carbon markets, support of partner agencies, and the securing of land rights.

Beyond carbon credits, access to technology holds promise for sustained improvements to adaptive fire management built on strong foundations of traditional burning practices.

Situational awareness is an essential component of wildland firefighter safety. In the US, crew lookouts provide situational awareness by proxy from ground-level locations with visibility of both fire and crew members.

To use machine learning to predict potential lookout locations based on incident data, mapped visibility, topography, vegetation, and roads.

Lidar-derived topographic and fuel structural variables were used to generate maps of visibility across 30 study areas that possessed lookout location data. Visibility at multiple viewing distances, distance to roads, topographic position index, canopy height, and canopy cover served as predictors in presence-only maximum entropy modelling to predict lookout suitability based on 66 known lookout locations from recent fires.

The model yielded a receiver-operating characteristic area under the curve of 0.929 with 67% of lookouts correctly identified by the model using a 0.5 probability threshold. Spatially explicit model prediction resulted in a map of the probability a location would be suitable for a lookout; when combined with a map of dominant view direction these tools could provide meaningful support to fire crews.

This approach could be applied to produce maps summarising potential lookout suitability and dominant view direction across wildland environments for use in pre-fire planning.

Knowledge of how fire regimes influence flammability, and its role in shaping future fire regimes, exists mostly at species composition and ecosystem levels. The effect of fire regimes on fuel at the chemical level is poorly known.

We aimed to empirically investigate the association between recent fire history and forest foliage chemistry; and to explore potential implications for forest fuel flammability.

Using an orthogonal study design, we investigated the effects of fire frequency and time since fire on the chemical composition of Eucalyptus pilularis leaves from forest canopies and surface litter in south-eastern Australia.

We found high fire frequency (fire-return interval 10–13 years) was associated with higher C:N, C:P, and C:K ratios in E. pilularis surface litter, and higher C:P in canopy leaves.

Nutrients including nitrogen and phosphorous reduce flammability of plant tissues, and hence, the observed differences in leaf nutrients between high and low fire frequency sites could have important implications for future flammability of these forests.

Our study has demonstrated a relationship between fire frequency and leaf nutrient stoichiometry, which may act as a mechanism through which repeated fires could increase fuel flammability. This warrants further investigation in other environments.

Prescribed burns are used to maintain wildland ecosystems and decrease fuel loads and associated wildfire hazard. Prescribed burns may produce enough smoke to cause adverse health outcomes. The aim of this review is to understand what communication materials exist for disseminating health risk information related to prescribed burn smoke and challenges to developing such communication. We examined United States peer-reviewed literature from PubMed, Scopus, and Web of Science databases and conducted an environmental scan of grey literature including materials from federal, and several US state and local governments, organisations, and newspapers. While 63% of the included peer-reviewed literature focuses on wildfire health risk communication, the review suggests similar methods and messages can be adapted for prescribed burns. The environmental scan review indicates effective strategies use several communication modes, and reliable and timely messaging. There are state regulations for prescribed burn notification, but these do not require communication or education of health risks associated with smoke exposure. Smoke management guidelines often contain information about prescribed burn health risks, but these do not discuss health risk education. Opportunities to expand effective health risk communication include improving inconsistent messaging and inter-agency collaborations, and increasing public interactions, especially with vulnerable populations.

Fire models have used pyrolysis data from oxidising and non-oxidising environments for flaming combustion. In wildland fires pyrolysis, flaming and smouldering combustion typically occur in an oxidising environment (the atmosphere).

Using compositional data analysis methods, determine if the composition of pyrolysis gases measured in non-oxidising and ambient (oxidising) atmospheric conditions were similar. 

Permanent gases and tars were measured in a fuel-rich (non-oxidising) environment in a flat flame burner (FFB). Permanent and light hydrocarbon gases were measured for the same fuels heated by a fire flame in ambient atmospheric conditions (oxidising environment). Log-ratio balances of the measured gases common to both environments (CO, CO₂, CH₄, H₂, C₆H₆O (phenol), and other gases) were examined by principal components analysis (PCA), canonical discriminant analysis (CDA) and permutational multivariate analysis of variance (PERMANOVA).

Mean composition changed between the non-oxidising and ambient atmosphere samples. PCA showed that flat flame burner (FFB) samples were tightly clustered and distinct from the ambient atmosphere samples. CDA found that the difference between environments was defined by the CO-CO₂ log-ratio balance. PERMANOVA and pairwise comparisons found FFB samples differed from the ambient atmosphere samples which did not differ from each other.

Relative composition of these pyrolysis gases differed between the oxidising and non-oxidising environments. This comparison was one of the first comparisons made between bench-scale and field scale pyrolysis measurements using compositional data analysis.

These results indicate the need for more fundamental research on the early time-dependent pyrolysis of vegetation in the presence of oxygen.