Increasingly frequent extreme fire weather, fuel build-up, and expanding rural-urban interfaces in Europe are converging to produce more frequent large fires that concentrate a disproportionate share of burned area, emissions, and socio-ecological impacts. Documenting each emerging season enables tracking of how fire dynamics evolve informing mitigation and adaptation across a continent where pyrogeography is expanding northward and outward from its Mediterranean core. The March 2025-February 2026 fire season was the most severe on record since EFFIS began monitoring in 2006, with 19,629 km² burned, about three times the 2006-2024 average, 58.35 Mt of CO₂ emitted, and 39.3% of EU27 burned surface falling within protected sites. Ukraine, Spain and Portugal together accounted for around two-thirds of the total burned area, with Spain, Cyprus, Kosovo, Germany, and the United Kingdom setting national records. The defining event was a two-week window in August during which synchronous megafires across northwestern Iberia burned over 5,000 km² under record heat, drought and Fire Weather Index values, including the largest wildfires ever recorded in both Spain (401 km2) and Portugal (654 km2). Highimpact fires extended from the UK to France, the Balkans, Cyprus, and Türkiye. Overall this fire season forced the evacuation of over 116,000 people and caused 39 direct fatalities. The 2025-26 season further signals a shift in European wildfire dynamics, where traditional suppression-based strategies are overwhelmed by compound climate-fuel extremes, fire-prone conditions expand into previously low-risk regions, and megafire synchronicity emerges as a potentially recurring phenomenon at sub-continental scales.

Detailed characterization of forest structure is critical for applications ranging from production forestry and carbon monitoring to fire risk analysis or habitat and biodiversity assessments. Ground-based LiDAR technologies, such as terrestrial (TLS) and mobile (MLS) laser scanning, enable precise 3D mapping of trees, understorey, and ground, offering rich structural detail. Yet, extracting meaning from these dense, unstructured point clouds remains a persistent challenge that requires reliable and scalable segmentation methods.Earlier segmentation approaches have struggled to generalize across diverse forest types and acquisition conditions. Recent advances in deep learning (DL), particularly architectures designed for 3D data, offer new opportunities for robust and scalable forest structure modelling using ground-based point clouds. Nevertheless, their implementation in forestry remains limited, partly due to the difficulty of obtaining large, accurately labelled point clouds for training and evaluation.In this study, we benchmark the performance of six different implementations of four state-of-the-art DL architectures (PointNeXt, SuperPoint Transformer, Point Transformer V3 and OA-CNN) on the public SegmentedForests dataset, which contains over 850 million labelled points from 14 plots representing a range of coniferous and broadleaf forests scanned with both TLS and MLS. We assess segmentation performance across four ecologically meaningful classes: ground, understorey, stems, and canopy. The best-performing model, Point Transformer V3, achieved an overall mean Intersection over Union (mIoU) of 81.9%, confirming the strong potential of transformer-based architectures for forest point cloud segmentation.The benchmark analysis considers how segmentation accuracy varies across forest type, sensor, understorey density and forest maturity. We observe clear differences in segmentation difficulty across conditions, with coniferous plots being consistently easier to segment than broadleaf plots, and TLS point clouds yielding higher accuracies than MLS acquisitions. Furthermore, a dense understorey was found to significantly improve class-wise saliency despite increased terrain occlusion. Cross-testing confirmed high model stability when generalized to entirely unseen scenes. Together, these results provide the first comprehensive benchmark of modern DL models for forest segmentation from ground-based LiDAR point clouds and highlight key factors shaping their performance across forest structural diversity.

Background Prescribed burning (PB) has been used on UK heathlands for centuries, with controversy over its potential to heat organic-rich soils. In recent years accredited training has been available to UK land managers providing them with improved skills with which to burn safely.Aims We assessed the levels of soil heating beneath PBs undertaken by these upskilled teams and provide an assessment of a range of burns using the same methodology at each burn.Methods In-field measurements of soil (3 cm depth), above-ground temperatures and fire severity assessments were taken during eight PBs across the UK, conducted under mild weather conditions and complying with PB guidance.Key results Both organic-rich peaty soils and mineral soils received little heating during the PBs tested, with mean maximum soil temperatures of <43.4 degrees C, and surface mean maximum temperatures of 784.5 degrees C. Fire severity assessments indicated no below-ground organic matter loss.Conclusions When following new accredited training, and according to Department for Environment, Food and Rural Affairs current guidance, underlying soils were not subjected to high temperatures that could directly damage long-term carbon stores.Implications Our results provide valuable insights into soil temperatures reached during PBs, highlighting that well-planned fire can be used safely in respect to burning vegetation particularly over organic-rich peaty soils.

Given the increased likelihood of wildfires in boreal forests due to climate change, the feasibility of current and alternative post-fire forest management strategies needs to be better understood. We assess the acceptability of post-fire management options through a survey experiment aimed at both forest owners and other forest users in Gävleborg county in Sweden—a region that experienced severe fires in 2018. We find that more than 90

Background Fires in temperate dry heaths burn dead and live fuels and are increasing in frequency. Models that describe these fuels and their contribution to fire behaviour is becoming of greater importance.Aims We sought to identify variations in fuel moisture and flammability in dry heath fuel types throughout the year and assess the strength of phenological shifts to influence predicted fire behaviour.Methods Six plant species from three dry heaths in the United Kingdom (UK) were collected throughout the year, their moisture content and effective heat of combustion measured. Data were used to parameterise a dynamic fuel model and undertake a sensitivity analysis using BehavePlus.Key results Phenological changes in live fuel moisture had the greatest effect on predicted fire behaviour where variations between late winter-early spring and late spring-summer, led to a four-fold difference in fire rate of spread. Dead fuel moisture had an effect in the summer months but was dampened significantly by phenologically high live fuel moisture content.Conclusions Phenological drivers of live fuel moisture in temperate shrubland fuels must be included in models that predict fire behaviour.Implications Using the data presented, models such as BehavePlus can be adapted to include this variability to predict fire behaviour in temperate heathland ecosystems.

Wildfire risk is increasing in temperate regions like the UK and NW Europe, but we lack operational tools to support wildfire management decision-making needs. We developed FireInSite to address the need for a user-oriented system for predicting fire behaviour. FireInSite is a fire behaviour prediction system in the form of a web-based application that forecasts the probability of ignition, surface fire rate of spread, flame length and fireline intensity for a user selected location for a set of core UK fire prone fuels. By seamlessly integrating geolocated weather forecasts up to 5 days ahead, topographic data, and in-built UK specific fuel models, FireInSite creates an accessible system that removes barriers like the need to gather data from multiple sources and is designed to minimise the number of inputs and decisions users must make before being able to predict fire behaviour. FireInSite can be used to assess the risk of fire in a particular area, plan for fire prevention and suppression, assess the potential effects of fuel load reduction, and educate the public about fire behaviour. We envision FireInSite being useful as a land management planning tool to assess the potential impacts of proposed landscape changes on potential fire behaviour.FireInSite is built on over four years of intensive data collection of fuel moisture, fuel flammability, and energy contents measured across the UK for key fire prone vegetation types, which have been used to develop fuel models that describe the fire prone fuel types of the UK landscape for the first time. No other fire behaviour prediction system contains fuel models that have been specifically designed and tailored to UK vegetation and are ready inbuilt for use in the system. It also allows the user to select custom developed fuel moisture models, explore past fire behaviour using historical weather records back to 1970, and compare weather and fuel moisture forecasts to conditions in previous years. As FireInSite fuel models capture seasonal variability in fuel flammability and moisture for a range of temperate, humid fuels, we anticipate that FireInSite will also be transferable and of interest for wildfire management in other temperate regions like north western Europe.

Background Fire and herbivores are essential to savanna ecosystems, consuming vegetation and recycling nutrients. Fire volatilises some elements and makes others readily available through ash, while herbivores redistribute nutrients via dung (excrement, faeces).Aims We investigate, for the first time, fire's role in consuming dung and affecting nutrient cycling.Methods We examined the chemical characteristics of wild large herbivore dung (buffalo, elephant, giraffe, wildebeest, zebra) burned during African savanna fires (Kruger National Park, South Africa) and estimated carbon and nutrients losses from dung burning.Key results Smouldering combustion of dung led to high carbon loss to the atmosphere (C: 41% and 4.1% in unburned and burned dung) and high enrichment of nutrients (e.g. Ca, P) and metals (e.g. Cu, Fe, Zn) in the burned residue. Flaming combustion of grass resulted in lower carbon loss (C: 43% and 23% in vegetation and ash), leaving more carbon in the ash and lower relative enrichment of other nutrients and metals.Conclusions Burned dung forms nutrient hotspots with physicochemical characteristics distinct from vegetation ash.Implications Taking dung from wild or domestic herbivores into account in fuel inventories can improve estimations of fire-related carbon emissions and provide better understanding of fire impacts on nutrients cycling.

Southern African savanna fires account for ~30% of the annual global carbon (C) emissions from vegetation fires, but their impact on the global C cycle extends beyond direct emissions During fire, part of the C burnt is converted to pyrogenic carbon (PyC), which is more resistant to degradation than original biomass and acts as a buffer to global fire C emissions when stored in soils or sediments. Despite its recognized importance for the C cycle, how much PyC is produced and how much of it stays in savanna ecosystems is still not well known, with no information yet for Southern African savannas. To address this research gap, we quantified how much PyC was produced during four fires in Kruger National Park (South Africa) and how much PyC was stored in surface soils. We also characterized the chemical and thermal recalcitrance of this PyC. Our results will be discussed in the broader context of C emissions from savanna fires as well as the role PyC plays as a C sequestration mechanism through its accumulation in soils, redistribution and ex-situ transport.

Fire regimes are changing across the globe, with new wildfire behaviour phenomena and increasing impacts felt, especially in ecosystems without clear adaptations to wildfire. These trends pose significant challenges to the scientific community in understanding and communicating these changes and their implications, particularly where we lack underlying scientific evidence to inform decision-making. Here, we present a perspective on priority directions for wildfire science research-through the lens of academic and government wildfire scientists from a historically wildfire-prone (USA) and emerging wildfire-prone (UK) country. Key topic areas outlined during a series of workshops in 2023 were as follows: (A) understanding and predicting fire occurrence, fire behaviour and fire impacts; (B) increasing human and ecosystem resilience to fire; and (C) understanding the atmospheric and climate impacts of fire. Participants agreed on focused research questions that were seen as priority scientific research gaps. Fire behaviour was identified as a central connecting theme that would allow critical advances to be made across all topic areas. These findings provide one group of perspectives to feed into a more transdisciplinary outline of wildfire research priorities across the diversity of knowledge bases and perspectives that are critical in addressing wildfire research challenges under changing fire regimes.This article is part of the theme issue 'Novel fire regimes under climate changes and human influences: impacts, ecosystem responses and feedbacks'.

Climate change is increasing wildfire frequency and severity, expanding into ecosystems less historically prone to wildfires, such as temperate peatlands. These peatlands are significant potable water sources that have accumulated legacy contaminants for decades. A major concern and uncertainty for ecosystem health and drinking water supply is the timing and magnitude of pollutant release, particularly potentially harmful metals, following extreme disturbances. Here, we examine mobilisation of legacy metals in a contaminated temperate blanket peatland following extreme drought and wildfire occurrence, focussing on key metal sources, transport pathways and deposition on the lake-bed of the receiving reservoir. We found that erosion of metal-rich hillslope peat and ash peaked three months post-wildfire, particularly in extreme burn severity areas, contributing to substantial deposition of metal-rich material in the receiving reservoir. Elevated metal concentrations in suspended sediments were observed nine months post-wildfire during spring rainstorm events. Dissolved metals in the streamflow were comparatively orders of magnitude lower, but displayed similar timing in concentration increases. Together this indicates limited acute but potential chronic impacts that extend beyond our study’s monitoring period. These pathways can present different challenges for managing water supplies. Our findings provide critical insights into the spatio-temporal dynamics of metal transport in peatlands following severe drought and wildfire. Understanding these pathways is essential for assessing current and future risks to water quality and developing targeted management strategies in northern peatland regions that are reliant on peat-rich catchments for drinking water and that are increasingly vulnerable to climate-induced disturbances.

Wildfires play an important role in the global carbon cycle, influencing both atmospheric carbon concentrations and terrestrial carbon storage. The production of pyrogenic carbon (PyC; the C-enriched product of incomplete combustion) is a globally significant buffering mechanism for fire-related carbon emissions. PyC production varies widely with vegetation fuel and fire characteristics, and data on the production rates for PyC for specific ecosystems, fuel components and fire severities remain scarce. This limits our understanding of the quantitative importance of PyC production, its role in the carbon budgets of fire-affected ecosystems, and our ability to modify planned fires towards maximizing this long-term carbon store. Eucalypt forests, which incur frequent wildfires and human-prescribed fires, provide an important context for understanding PyC dynamics. Here we quantify PyC production in experimental fires conducted with low- to moderate fire severities in three Eucalyptus forest types across southern Australia. This involved comprehensive pre and post-fire fuel inventories and quantifying all pyrogenic materials generated in eucalypt forest sites near Sydney, Melbourne, and Perth. We also estimate PyC conversion rates in the main fuel components: forest floor, understory, down wood, and overstory (comprising only tree bark as these surface fires did not affect the crowns). Our results show that, of all the carbon affected by the fire, 2.7 t C ha-1 (2.4 - 3.1 t C ha-1) was transformed into PyC and 9.3 t C ha-1 (7.9 - 11.0 t C ha-1) emitted to the atmosphere. This translates into an average pyrogenic carbon conversion rate of 23 % of carbon affected by fire, underscoring the relevance of PyC in carbon budgets from eucalypt forest fires. The conversion rates varied substantially among fuel components, with the bark exhibiting the highest conversion rate, at approximately 40 %, and the down wood component displaying the lowest rate at around 15 %. Intermediate conversion values were found for forest floor and understory components (20 % and 31 %, respectively). Our findings highlight the critical importance of bark in PyC production in low to moderate fires, an aspect frequently overlooked in general inventories. Given the high fire recurrence in eucalypt forests in Australia, both naturally and under human-prescribed conditions, and the expansion of eucalypt plantations in many regions around the world, our findings are relevant for fire-related carbon budget estimations at both regional and global levels and can inform the optimization of prescribed burning for reducing carbon emissions.

Wildfires release approximately 2.1 Pg C to the atmosphere each year. The impact of wildfires on the carbon cycle, however, extends well beyond direct emissions, involving complex interactions among various source and sink processes. One such process, the enhanced post-fire soil organic carbon (SOC) erosion, remains unquantified as a potential C sink mechanism. Post-fire SOC erosion functions as a C sink when the subsequent burial and stabilization of eroded C offsite, coupled with the recovery of net primary production and SOC content onsite, outweigh the C losses to the atmosphere during post-fire transport of SOC. In this work, we synthesize published data on post-fire SOC erosion and evaluate its overall potential to act as C sink. In addition, we estimate its magnitude at continental scale following the 2017 wildfire season in Europe, showing that SOC erosion can indeed play a quantitatively significant role in the overall C balance of wildfires.

Prescribed (Rx) and controlled fires are an important land management tool used globally for a variety of reasons, including the reduction of hazardous fuel loads, ecological conservation, agriculture, and natural resource management. Its use has important implications for wildfire risk, biodiversity, and carbon storage. However, the use of Rx and controlled fires is highly dependent upon weather conditions, requiring a weather window during which a careful balance of temperature, moisture, and wind ensure that the burns achieve their objectives while minimizing ecological damage or risk to human lives or assets. The planning and execution of Rx burns must also consider how these weather conditions interact with the local vegetation and ecology. As fire weather is projected to grow more extreme under the impacts of climate change, there is a growing need to monitor this effect on the ability to carry out Rx burning. Here, we introduce a new dataset, GlobalRx, which includes around 140,000 records of Rx and other controlled fires from 16 countries, encompassing 207 ecoregions and 13 biomes around the world. For each record, we have geolocated values of various metrics of fire weather and fire danger (e.g. fire weather indices, vapour pressure deficit) from the ERA5 meteorological reanalysis, as well as the biome, ecoregion, fuelbed type, and protected area status from global thematic layers. We demonstrate the usefulness of this dataset for analyzing viable meteorological windows under which Rx fires may be conducted across diverse environmental settings in the present climate, as well as how these Rx burning windows may shift under the threats of climate change. This dataset has potential to shed light on how Rx burning windows may shift under future climate change, as well as opportunities to understand other drivers and effects of Rx burning. This project has been supported by valuable contributions from non-public data from a consortium of data providers: Parks Canada, South Africa National Parks, Brazilian Institute of the Environment and Renewable Natural Resources, East-Pyrenees Prescribed Burning Team, Institute for Nature Conservation and Forests (Portugal), Regional Forest Fire Service (Italy), Russian Federal Forestry Agency, H2020 LifeTaiga Project, Government of the Principality of Asturias, Council of Andalucía, Council of Galicia, Forestry England, National Forestry Commission of Mexico, ZEBRIS Geo-IT GmbH, Hokkaido University, Pau Costa Foundation, Asian Forest Cooperation Organization.

Fire weather indices are used widely as predictors for landscape fire potential. However, for the United Kingdom (UK: England, N-Ireland, Scotland and Wales) and comparable regions of humid-Atlantic Europe, they do not correlate well with fire occurrence. Here we explore the role of vegetation phenology as a key driver for fire occurrence in the UK.We mapped satellite-derived fire occurrence and phenology climatology for 2012-2023 onto main fire-affected vegetation cover types within distinct precipitation regions for the UK. This enabled fire occurrence for fuels in different phenological phases to be explored across distinct ‘fuel’ types and regions.Semi-natural grassland and dwarf shrub-dominated land emerged as the prominent fire affected ecosystems across much of the UK. We found that, critically, fire occurrence for vegetation at its maximum greenness were reduced by a factor of five to six compared to dormant vegetation, despite higher fire weather indices being typically associated with the former.In contrast to most regions of the world that exhibit more extreme fire weather, fire activity in the UK’s humid Atlantic climate therefore seems strongly governed by vegetation phenology. This suggests that incorporating vegetation phenology is la critical step in the development of robust fire risk and behaviour prediction systems for regions with similar climate. It should be noted, however, that we also found evidence of that this fire-suppressing phenology barrier can be broken during extreme summer heat/drought events, which are likely to increase in frequency and severity under changing climate. Hence fire weather indices remain critical predictors during the currently still rare extreme summer heat/drought events.

The long-term carbon storage capacity of the boreal forest is under threat from the increasing frequency and intensity of wildfires. In addition to the direct carbon emissions during a fire, the burnt forest often turns into a net carbon emitter after fire, leading to large additional losses of carbon over several years. Understanding how quickly forests recover after a fire is therefore vital to predicting the effects of fire on the forest carbon balance. We present soil respiration and CH4 fluxes, soil chemistry, microclimate and vegetation survey data from the first four years after a wildfire in a Pinus sylvestris forest in Sweden. This is an understudied part of the boreal biome where forest management decisions interact with disturbances to affect forest growth. We analysed how fire severity and post-fire salvage-logging affected soil carbon fluxes. The fire did not affect soil CH4 uptake. However, soil respiration was significantly affected by the presence or absence of living trees after the fire and postfire forest management. Tree mortality due to the high-severity fire, or the salvage-logging of living trees after low-severity fire, led to immediate and significant decreases in soil respiration. Salvage-logging of dead trees after high-severity fire did not alter soil respiration compared to when the dead trees were left standing. However, it did significantly slow the regrowth of understory vegetation. Our results highlight that the impact of salvage-logging on the soil carbon fluxes depends on fire severity but that logging always slows the natural recovery of vegetation after fire. The soil CO2 fluxes did not show signs of recovery at any of the burnt sites during the first four years since the fire.

Herbivores play a vital role in the functioning of savanna ecosystems. They ingest plants, modifying the vegetation cover, and disperse nutrients across the landscape in the form of dung. Fire in savanna is also a key nutrient recycling pathway, making elements readily available through the resultant ash and smoke. Wildfire ash, known for its susceptibility to be transported by wind and water, plays a key role in redistributing pyrogenic organic matter and nutrients across the landscape. However, our level of understanding of ash characteristics from burnt dung is very low. In addition, and due to its high carbon content, dung also adds to the wildland fuels for fires, alongside vegetation. Given that savannas are the dominant source of global C emissions from fires, assessing the role of burnt dung in C dynamics is, therefore, also crucial for more accurate estimations of the overall C released during savanna fires. We quantified C losses from dung combustion during fire in four savanna sites burnt by experimental fires in Kruger National Park (South Africa). We also analysed chemical properties, including major nutrients and metals, of dung and dung-derived ash. The studied dung came from large herbivores (zebra, elephant, giraffe, buffalo and wildebeest). The concentration of carbon and nitrogen in burnt dung was significantly lower than unburnt dung (carbon: 41 and 4.1%, nitrogen: 1.1 and 0.3% in unburnt and burnt dung, respectively). The carbon released from dung burning accounted for up to 6% of the carbon released from vegetation burning, emphasizing the substantial role of dung in carbon emissions during savanna fires. Our results also highlight burnt dung as a hotspot for minerals and nutrients with chemical characteristics different to those found in vegetation ash (e.g., phosphorus: 9,195 and 6,158 mg kg-1, copper: 55.8 and 28.1 mg kg-1 in dung-derived and vegetation ash respectively). This is likely to affect local soil physical and chemical properties and hence enhance ecosystem diversity.

Prescribed burning (RxB) is a land management tool used widely for reducing wildfire hazard, restoring biodiversity, and managing natural resources. However, RxB can only be carried out safely and effectively under certain seasonal or weather conditions. Under climate change, shifts in the frequency and timing of these weather conditions are expected but analyses of climate change impacts have been restricted to select few regions partly due to a paucity of RxB records at global scale. Here, we introduce GlobalRx, a dataset including 204,517 RxB records from 1979-2023, covering 16 countries and 209 terrestrial ecoregions. For each record, we add a comprehensive suite of meteorological variables that are regularly used in RxB prescriptions by fire management agencies, such as temperature, humidity, and wind speed. We also characterise the environmental setting of each RxB, such as land cover and protected area status. GlobalRx enables the bioclimatic range of conditions suitable for RxB to be defined regionally, thus unlocking new potential to study shifting opportunities for RxB planning and implementation under future climate.

Wildfires play an important role in the carbon cycle, influencing both atmospheric carbon concentrations and terrestrial carbon storage. Pyrogenic carbon (PyC) derived from incomplete biomass combustion during wildfires is currently considered a relevant carbon sink at the global level. In order to assess the quantitative importance of PyC production, accurate data on PyC generation in different ecosystems and under a range of fire conditions are needed. In this study, we focus on the fire-prone continent of Australia, specifically on eucalypt forests, which are the most common type of native forests. Eucalypt forests, subjected frequently to both wildfires and human-prescribed fires, provide an important context for understanding PyC dynamics.We conducted comprehensive pre-fire and postfire fuel inventories and quantified all pyrogenic materials generated in three representative eucalypt forests in Sydney, Melbourne, and Perth. Experimental fires, simulating low to medium-severity wildfires, were used to quantify PyC conversion rates in the main fuel components: forest floor, understory, down wood, and overstory (comprising only tree bark as these fires did not affect the crowns).Our results show an average pyrogenic carbon conversion rate of 24% for eucalypt forests. This translates to 9 t C ha-1 of the carbon affected by the fire being emitted to the atmosphere, while 3 t C ha-1 is transformed into PyC, underscoring the relevance of PyC in carbon budgets from eucalypt forest fires. The conversion rates varied substantially among fuel components, with the bark component exhibiting the highest conversion rate, at approximately 40%, and the down wood component displaying the lowest rate at around 15%. Intermediate conversion values were reported for forest floor and understory components. Given the recurrent nature of fires in eucalypt forests in Australia, both naturally and under human-prescribed conditions, our findings suggest that PyC production plays a significant role in the carbon cycle, of sufficient magnitude to be considered in global carbon budget estimations.

Soil and ash are key sources of sediment, carbon, nitrogen, and associated pollutant movement following a wildfire. Their transport into freshwater systems can pose severe environmental and socio-economic implications including impacts to water quality and aquatic ecosystems, disruptions to drinking water supply and high remediation costs, as well as the depletion of carbon and nutrients from areas affected by erosion. We assessed the risk of soil erosion, ash and contaminant transport, and water contamination in three burned European catchments in Central Europe (Germany and the Czech Republic), Portugal and Spain using the European Water Erosion Prediction Project cloud interface with the Wildfire Ash Transport and Risk (WEPPcloud-EU WATAR) watershed model. The watersheds varied in size from 100 to 22,000 ha and represent distinct climatic conditions. To our knowledge, this is the first application of this model in European post-fire scenarios. We calibrated and validated the model using catchment runoff data (where available) and nearby streamflow data from both pre- and post-fire periods when runoff data was unavailable. Additionally, we used sediment transport data (where available) along with ash contaminant content data to calibrate and validate erosion and ash transport rates. Model performance was assessed using statistics like Nash-Sutcliffe Efficiency (NSE), coefficient of determination (R2) and percent bias (PBias (%)). Once the model was calibrated and validated, we estimated the post-fire risk of soil erosion, ash transport, and ash pollutant concentrations in the affected areas. The simulations provided the probabilities of occurrence and return periods for severe erosion events, as well as for ash and contaminant transport events. Based on these simulations, we identified hillslopes that were the main sources of runoff, erosion, ash and contaminant transport. This information is important to managers who can prioritize the application of mitigation treatments and prevention plans. Given the projected increase in fire weather in many regions in Europe, our findings suggest that the WEPPcloud-EU WATAR model is an increasingly useful tool in predicting and mitigating soil erosion and water contamination impacts of European burnt catchments.

Climate change is resulting in more extreme fire weather during major heatwaves. Across temperate Europe, shrub landscapes dominate the area burned, with the moisture content of fuels during these events determining the threat posed. Current controls on the moisture content of temperate fuel constituents and their response to future extreme heatwaves are not known. We took field measurements of live and dead heather (Calluna vulgaris) and organic soil moisture content across the UK over 3 years, including an intensive sampling campaign during the July 2022 heatwave. Here, we show that the fuel moisture content of live fuel is associated significantly with phenological variables, dead fuel only with weather variables, whilst organic-rich ground fuels are more associated with landscape variables. However, during the record 2022 heatwave there was a harmonisation in fuel moisture controls across different fuel constituents, with those controls being driven by weather alone. This caused synchronised extreme dryness outside of current seasonal norms across all fuel constituents at the same time and place. Future intense summer heatwaves can therefore be expected to align the most severe conditions for fire ignition, spread and impact in traditionally non-fire prone regions, producing humid temperate landscapes susceptible to extreme wildfire events.