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The 9th International Conference on Forest Fire Research, organised by the Forest Fire Research Center of the Association for Developmental of Industrial Aerodynamics every 4 years since 1990, was held in November 2022 in Coimbra, Portugal. The conference was held in conjunction with the 17th International Wildland Fire Safety Summit, sponsored by the International Association of Wildland Fire. The number and quality of the submissions for this joint event was very high, and the authors were encouraged to submit a full paper to a special issue of the International Journal of Wildland Fire (IJWF). Given the large number of submissions, the Journal decided to publish the special issue in four parts. Part 1 was published in January 2023, with eight papers, Part 2 in March 2023, with 10 papers and Part 3 in June 2023 with 15 papers. This fourth part presents 10 original papers, in three areas: Decision Support Systems and Tools (3), Risk Assessment & Reduction (3) and the Wildland Urban Interface (4). All the papers in this special issue are published Open Access. Part 4 of the special issue that resulted from the 9th International Conference on Forest Fire Research includes 10 papers on various aspects of wildland fire research. Parts 1, 2 and 3 were published in January, March and June 2023 respectively. All papers in the special issue are published Open Access. [ABSTRACT FROM AUTHOR]

The ninth International Conference on Forest Fire Research, organised by the Forest Fire Research Center of the Association for Developmental of Industrial Aerodynamics every 4 years since 1990, was held in November 2022 in Coimbra, Portugal. The conference was held in conjunction with the 17th International Wildland Fire Safety Summit, sponsored by the International Association of Wildland Fire. The number and quality of the submissions for this joint event was very high, and the authors were encouraged to submit a full paper to a special issue of the International Journal of Wildland Fire (IJWF). Given the large number of submissions, the Journal decided to publish the special issue in several parts. Part 1 was published in January 2023, with eight papers, and Part 2 in March 2023, with 10 papers. This third part presents 15 original papers in five topical areas: decision support systems and tools (3), risk reduction (2), risk assessment (3), wildland urban interface (3) and wildfire management and safety (4). All the papers in this special issue are published Open Access. [ABSTRACT FROM AUTHOR]

The ninth International Conference on Forest Fire Research (ICFFR) was recently held in Coimbra, Portugal, bringing together scientists and fire managers from around world to advance and update knowledge in the area of fire management. The conference was held jointly with the International Association of Wildland Fire's 17th International Wildland Fire Safety Summit (IWFSS). Here we introduce Part 1 of a special issue series arising from the 2022 ICFFR/IWFFS joint meeting. This issue of the International Journal of Wildland Fire contains eight papers covering a wide variety of topics including: seasonal fire activity and spatio-temporal fire-weather patterns under climate change, the role of atmospheric conditions on fire and flaming zone behaviour, analytical techniques for measuring oxidative pyrolysis gases, particulate morphology of fires in the wildland–urban interface, deep peat fire smouldering and the impact of post-fire treatments on soil. All papers in the issue are published Open Access. Here we introduce Part 1 of a special issue series arising from the IX International Conference on Forest Fire Research, held 14–18 November 2022, Coimbra, Portugal. This issue comprises eight papers covering a wide variety of topics. All papers in the issue are published Open Access. [ABSTRACT FROM AUTHOR]

Background and aims: Infrared thermal images of a propagating wildfire taken by manned or unmanned aerial vehicles can help firefighting authorities with combat planning. Segmenting these images into regions of different fire temperatures is a necessary step to measure the fire perimeter and determine the location of the fire front. Methods: This work proposes a multilayer segmentation method based on level sets, which have the property of handling topology, making them suitable to segment images that contain scattered fire areas. The experimental results were compared using hand-drawn labels over a set of images provided by the Portuguese Air Force as ground truth. These labels were carefully drawn by the authors to ensure that they complied with the requirements indicated by the Portuguese National Authority for Emergency and Civil Protection. The proposed method was optimised to ensure contour smoothness and reliability, as well as reduce computation time. Key results: The proposed method can surpass other common unsupervised methods in terms of intersection over union, although it has not yet been able to perform real-time segmentation. Conclusions: Although falling out of use in relation to supervised and deep learning methods, unsupervised segmentation can still be very useful when annotated datasets are unavailable. The infrared thermal images of a propagating wildfire taken by aerial vehicles can help firefighting authorities in combat planning. We propose a method that is able to separate the wildfire into different temperature regions, which facilitates identification of the fire perimeter and location of the active front. (This paper is part of a Special Issue that includes papers on research presented at the IX International Conference on Forest Fire Research, Coimbra, Portugal, November 2022.) [ABSTRACT FROM AUTHOR]

Background: Wildfires are a growing threat to many ecosystems, bringing devastation to human safety and health, infrastructure, the environment and wildlife. Aims: A thorough understanding of the characteristics determining the susceptibility of an area to wildfires i s crucial to prevention and management activities. The work focused on a case study of 13 countries in the eastern Mediterranean and southern Black Sea basins. Methods: A data-driven approach was implemented where a decade of past wildfires was linked to geoclimatic and anthropic descriptors via a machine learning classification technique (Random Forest). Empirical classification of fuel allowed linking of fire intensity and hazard to environmental drivers. Key results: Wildfire susceptibility, intensity and hazard were obtained for the study area. For the first time, the methodology is applied at a supranational scale characterised by a diverse climate and vegetation landscape, relying on open data. Conclusions: This approach successfully allowed identification of the main wildfire drivers and led to identification of areas that are more susceptible to impactful wildfire events. Implications: This work demonstrated the feasibility of the proposed framework and settled the basis for its scalability at a supranational level. In this work, wildfire susceptibility, intensity and risk were obtained for the eastern Mediterranean and southern Black Sea basins. A methodology that combines machine learning techniques and empirical modelling is applied at a supranational scale characterised by a diverse climate and vegetation landscape, relying on open data. (This paper is part of a Special Issue that includes papers on research presented at the IX International Conference on Forest Fire Research, Coimbra, Portugal, November 2022.) [ABSTRACT FROM AUTHOR]

Background: Swedish wildfires are handled by multipurpose municipal rescue services, raising questions about how non-specialist incident commanders (ICs) perceive and interpret wildfire behaviour. Aims: Elucidating ICs' interpretations of fire behaviour, fuel complexes, weather, landscape structure and the role of these in tactical decisions. Methods: We exposed Swedish ICs to questionnaires and tabletop exercises for different standardised fire scenarios. Key results: Despite minimal formal wildfire training, ICs showed reasonable consensus in rating of fuels, fire behaviour, hose-lay production rates, etc. Tactics were to access the fire from the nearest road with hose-line laid from the engine and water ferried on trucks. In a scenario where initial attack failed, they typically fell back to roads, without burning off. This indicates a fundamental flaw in tactics employed for high-intensity fires, which easily breach forestry roads, and invite outflanking. Conclusions: The IC wildfire knowledge is built on personal and group experience rather than formal education. We found reasonable competence, despite the organisations being designed primarily for other purposes. However, tactical understanding of complex, large incidents was poor. IC training should emphasise potential hazards of such incidents to enhance group competence despite their low frequency. Implications: Standardised tabletop exercises can provide insight into decision-making of ICs that is otherwise hidden. In regions with high wildfire potential but a low frequency of complex incidents, perceptions of wildfire behaviour can vary significantly among incident commanders. This study shows how incident commanders' a priori understanding of wildfire affects their decisions during incidents, and how tabletop exercises can be used to extract such information. (This paper is part of a Special Issue that includes papers on research presented at the IX International Conference on Forest Fire Research, Coimbra, Portugal, November 2022.) [ABSTRACT FROM AUTHOR]

Background: Wildfires propagate through vegetation exhibiting complex spread patterns modulated by ambient atmospheric wind turbulence. Wind gusts at the fire-front extend and intensify flames causing direct convective heating towards unburnt fuels resulting in rapid acceleration of spread. Aims: To characterise ambient and fire turbulence over gorse shrub and explore how this contributes to fire behaviour. Methods: Six experimental burns were carried out in Rakaia, New Zealand under varying meteorological conditions. The ignition process ensured a fire-line propagating through dense gorse bush (1 m high). Two 30-m sonic anemometer towers measured turbulent wind velocity at six different levels above the ground. Visible imagery was captured by cameras mounted on uncrewed aerial vehicles at 200 m AGL. Key results: Using wavelet decomposition, we identified different turbulent time scales that varied between 1 and 128 s relative to height above vegetation. Quadrant analysis identified statistical distributions of atmospheric sweeps (downbursts of turbulence towards vegetation) with sustained events emanating from above the vegetation canopy and impinging at the surface with time scales up to 10 s. Conclusions: Image velocimetry enabled tracking of 'fire sweeps' and characterised for the first time their lifetime and dynamics in comparison with overlying atmospheric turbulent structures. Implications: This methodology can provide a comprehensive toolkit when investigating coupled atmosphere–fire interactions. Multi-modal observations of fire behaviour and overlying atmospheric turbulence were carried out for four wind-driven gorse bush experimental fires. Novel image velocimetry analysis outlined the dynamics and scales of motion of fire sweeps in relation to overlying atmospheric coherent turbulent structures. Results are useful for evaluating coupled fire–atmosphere model simulations. (This paper is part of a Special Issue that includes papers on research presented at the IX International Conference on Forest Fire Research, Coimbra, Portugal, November 2022.) [ABSTRACT FROM AUTHOR]

Background: Identifying if and how climatic and non-climatic factors drive local changes in fire regimes is, as in many other human-dominated landscapes, challenging in south-eastern France where both heterogeneous spatial patterns and complex fire trends are observed. Aim: We sought to identify the factors driving the spatial-temporal patterns of fire activity in southeastern France. Methods: We incorporated several non-climatic variables into the probabilistic Firelihood model of fire activity and implemented an enhanced spatio-temporal component to quantitatively assess remaining unexplained variations in fire activity. Key results: Several non-climatic drivers (i.e. orography, land cover and human activities) contributed as much as fire-weather to the distribution of fire occurrence (>1 ha) but less to larger fires (>10, 100 and 1000 ha). Over the past decades, increased fire-weather induced a strong increase in wildfire probabilities, which was actually observed on the western part of the region but not so in the east and Corsican Island, most likely due to reinforced suppression policies. Conclusions: While spatial patterns in fire activity are driven by land-use and land-cover factors, temporal patterns were mostly driven by changes in fire-weather and unexplained effects potentially related to suppression policies but with large differences between regions. We leveraged Bayesian spatio-temporal modelling to disentangle the contributions of climatic and non-climatic drivers for fire activity in Mediterranean France. We showed that recent fire-weather increase caused the increase of fire probability in the west; but in the east, it was over-compensated by a reduction of escaped-fire probability. (This paper is part of a Special Issue that includes papers on research presented at the IX International Conference on Forest Fire Research, Coimbra, Portugal, November 2022.) [ABSTRACT FROM AUTHOR]

Background: Mulching and burnt wood treatments are commonly applied to prevent the loss of soil quality and erosion, but their effect on soil multifunctionality remains unexplored. Aims: We filled this gap by assessing the medium-term (4 years) effects of these treatments on soil multifunctionality after a large wildfire in NW Spain. Methods: Straw mulching (SM) and cut plus lopping (CpL) treatments were applied in high-severity affected areas of heathland plant communities. CpL areas had been afforested with Scots pine 15 years before the fire. We considered four soil functions estimated in treated and burned control plots 4 years after fire: (1) carbon regulation; (2) water regulation; (3) soil fertility; and (4) nutrient cycling. The functions were integrated into a multifunctionality index and linear models were used to evaluate treatments effect. Key results: SM had no impact on individual functions and multifunctionality. Conversely, CpL with burnt Scots pine wood was able to sustain higher levels of multiple functions simultaneously than control areas. Consistent trade-offs between soil functions emerged in control areas for both treatments. Conclusions: Burnt wood could ensure long-lasting effects to promote soil multifunctionality in Mediterranean ecosystems. Implications: We recommend using a multifunctionality approach to avoid biases in treatment success. Post-fire treatment consisting of leaving burnt logs and felled branches in close contact with the forest floor promotes the ability of the soil to sustain high values of multiple functions simultaneously in the medium term after wildfire, as compared to straw mulching application. (This paper is part of a Special Issue that includes papers on research presented at the IX International Conference on Forest Fire Research, Coimbra, Portugal, November 2022.) [ABSTRACT FROM AUTHOR]