Wildfire Regimes Research Articles

Characterizing the Wildfire Patterns in the Marromeu Complex Using Remote Sensing Data

Objective: To caraterize the wildfire regime in the Marromeu Complex between 2002 and 2019. Method: Data from the MOD14 Collection 6 sensor, pertaining to thermal anomalies (MCD14ML, MCD64A1) corresponding to hot spots and burned areas, were used on a monthly basis. Only pixels with a reliability of 80% or higher were considered. Patterns of hot spots, burned area, density, intensity, frequency, and seasonality of fires were analyzed. Data processing was conducted using ArcGIS 10.8. Results and Discussion: A total of 12,227 hot spots were identified, covering 73% of the burned area. The annual average burned area was 24%, with densities ranging from moderate to very high. The fires showed low intensity across most of the Complex, with an average fire frequency of 2 to 3 times per year, and the highest fire records were observed in September. These findings are analyzed within the theoretical framework, emphasizing the implications of temporal and spatial variations in fires and their potential causes and environmental impacts. Implications of the Research: This study offers insights into wildfire management and emphasizes the necessity of fire management strategies in the Marromeu Complex. The implications include enhancing management plans and mitigating environmental impacts associated with fires. Originality/Value: This study contributes to the literature by providing a detailed characterization of the fire regime in the Marromeu Complex. The research is relevant as it offers new information on fire dynamics and their variations over time, which could impact management practices and environmental policies.

Rising forest exposure and fire severity from climate warming amplify tree cover losses from wildfire in California

Abstract Warmer temperatures and severe drought are driving increases in wildfire activity in the western United States, threatening forest ecosystems. However, identifying the influence of fire severity on tree cover loss (TCL) is challenging using commonly used categorical metrics. In this study, we quantify regional trends in wildfire-driven TCL as the product of annual burned area, average forest exposure (pre-fire tree cover), and average fire severity (relative loss of tree cover). We quantified these trends with Landsat-based 30 m resolution fire and tree cover datasets for California wildfires from 1986–2021. Rates of TCL rose faster than trends in burned area, with the magnitude of tree cover area loss per unit of area burned increasing by 70% from 0.20 ± 0.05 during 1986–1996 to 0.34 ± 0.10 during 2011–2021. Forest exposure (pre-fire tree cover) within fires increased by 41% from a decadal mean of 23.4% ± 5.5% (1986–1996) to 33.1% ± 7.8% (2011–2021). Increasing forest exposure is associated with a recent expansion of fires in dense northern forests. Concurrently, fire severity (relative TCL) rose by 30% from a decadal mean of 50.4% ± 7.2% during 1986–1996 to 65.6% ± 6.5% during 2011–2021. We developed and applied a simple conceptual framework to quantify the combined effect of wildfires affecting denser forests and burning more severely. The combined effect of these two processes contributed to nearly half (47%) of the TCL since 1986, highlighting that recent changes in burned areas alone cannot explain observed tree cover trends. Linear regression analysis revealed that warmer summers and drier winters were significant drivers of increasing forest exposure, fire severity, and burned area (R 2 from 0.54 to 0.80, p ⩽ 0.001), particularly in the northern forests. Climate extremes had a disproportionate impact on dense forests that were once more resistant to wildfire but now face risks from a shifting wildfire regime.

Effects of fire and fire-induced changes in soil properties on post-burn soil respiration

Abstract Background Boreal forests cover vast areas of land in the northern hemisphere and store large amounts of carbon (C) both aboveground and belowground. Wildfires, which are a primary ecosystem disturbance of boreal forests, affect soil C via combustion and transformation of organic matter during the fire itself and via changes in plant growth and microbial activity post-fire. Wildfire regimes in many areas of the boreal forests of North America are shifting towards more frequent and severe fires driven by changing climate. As wildfire regimes shift and the effects of fire on belowground microbial community composition are becoming clearer, there is a need to link fire-induced changes in soil properties to changes in microbial functions, such as respiration, in order to better predict the impact of future fires on C cycling. Results We used laboratory burns to simulate boreal crown fires on both organic-rich and sandy soil cores collected from Wood Buffalo National Park, Alberta, Canada, to measure the effects of burning on soil properties including pH, total C, and total nitrogen (N). We used 70-day soil incubations and two-pool exponential decay models to characterize the impacts of burning and its resulting changes in soil properties on soil respiration. Laboratory burns successfully captured a range of soil temperatures that were realistic for natural wildfire events. We found that burning increased pH and caused small decreases in C:N in organic soil. Overall, respiration per gram total (post-burn) C in burned soil cores was 16% lower than in corresponding unburned control cores, indicating that soil C lost during a burn may be partially offset by burn-induced decreases in respiration rates. Simultaneously, burning altered how remaining C cycled, causing an increase in the proportion of C represented in the modeled slow-cycling vs. fast-cycling C pool as well as an increase in fast-cycling C decomposition rates. Conclusions Together, our findings imply that C storage in boreal forests following wildfires will be driven by the combination of C losses during the fire itself as well as fire-induced changes to the soil C pool that modulate post-fire respiration rates. Moving forward, we will pair these results with soil microbial community data to understand how fire-induced changes in microbial community composition may influence respiration.

Soil response in a Mediterranean forest ecosystem of Southeast Spain following early prescribed burning

The escalation of global warming, high temperatures, and wildfire frequency in dry ecosystems, including semi-arid landscapes, has resulted in increased wildfire regimes, compromising ecosystem resistance and resilience. To mitigate these risks, prescribed burning (PB) is being employed as a preventive measure to modify fuel loads in forest ecosystems. However, fire can also impact soil structure and microbiota, which play critical roles in nutrient cycling, biodiversity conservation, and overall ecosystem functioning. Therefore, understanding post-fire processes is essential for sustainable forest management. However, while previous studies have explored the effects of prescribed fire management on semi-arid soil properties in Mediterranean forest ecosystems, gaps remain in our understanding of its specific impact on the physical structure, chemical composition, and biological activities of soils.In this study, we conducted early spring PB in SE Spain in 2021 and assessed the ecological and temporal effects of PB on semi-arid soils. Soil respiration (SR) measurements using automatic CO2 flow chambers were employed to evaluate microbiota recovery. To examine impacts on soil structure we evaluated physicochemical characteristics, soil hydraulic conductivity (SHC), and soil water repellency (SWR). No significant differences were observed in any of the variables studied after one year. However, immediate effects were detected shortly after the PB. Our research specifically targeted soil structure and microbiota in a semi-arid landscape with poor soils, characterized by slower recovery and potentially fragile ecosystems. These results provide valuable insights for forest management practices, indicating that prescribed fire management strategies in similar ecosystems are unlikely to cause adverse effects on soil health. However, further research is warranted to explore the potential effects of prescribed fire intensity and seasonality. Future studies can focus on investigating these factors to provide more targeted recommendations for effective forest management strategies and wildfire prevention efforts.

Analysing the capacity of multispectral indices to map the spatial distribution of potential post-fire soil losses based on soil burn severity

The area burned in Spain exceeded historical records in 2022, when exceptionally warm conditions influenced wildfire events. The predicted intensification of wildfire regimes includes an increase in frequency, severity, and size. Therefore, a study of the wildfires that occurred in 2022 is necessary to understand their behaviour and possible environmental impacts. The objective of this study is to analyse the applicability of using spectral indices and Geographic Information System (GIS) approaches to map the spatial distribution and estimate potential soil losses using Sentinel-2 imagery and fire severity field data. Soil losses were estimated using an empirical model based on soil burn severity data collected in the field after wildfire. The relationship between the Normalized Difference Infrared Index (NDII), Difference Normalized Wildfire Ash Index (dNWAI), and the Blue Normalized Difference Vegetation Index (BNDVI) with the estimated soil losses was then evaluated. In addition, the influence of different time scales of the satellite images was analysed. The first period considered (Date I) ranges from 8 to 20 days after the beginning of the wildfire, which coincides with the field data collection. The second period considered (Date II) ranges from 28 to 35 days after the start of the wildfire. The results obtained showed a significant dependence relationship between the BNDVI index (using satellite images of Date I) and the estimated soil losses (R2 = 0.756), while the results of the NDII (R2 = 0.31) and dNWAI (R2 = 0.061), showed no spatial relationship with the estimated soil losses. Three of the largest wildfires in 2022 in Spain were analysed, and the results showed strong correlations of BNDVI index for Folgoso do Courel (R2 = 0.808), for Carballeda de Valedorras (R2 = 0.906), and for Sierra de la Culebra (R2 = 0.939). In addition, these results allowed the mapping and quantification of potential soil losses in areas where fire severity was high, totalling ∼2,50,000 Mg ha−1 in Folgoso do Courel, ∼3,70,000 Mg ha−1 in Carballeda de Valdeorras, and ∼4,70,000 Mg ha−1 in Sierra de la Culebra. Moreover, BNDVI values for estimating soil loss vary by vegetation type, and there is a positive correlation between severity classes and the BNDVI index. This approach can inform post-fire land management decisions in future wildfires and could be applied to other regions.

Escalating Wildfires in Siberia Driven by Climate Feedbacks Under a Warming Arctic in the 21st Century

AbstractSiberian wildfire is of paramount importance in the carbon cycle and climate change as it is a major disturbance in the pan‐Arctic ecosystems. In recent decades, the Siberian wildfire regime has been shifting; however, less is known about its process‐based feedback mechanisms. By integrating in‐situ and satellite observational data sets as well as chemistry‐climate coupled modeling, we find that central Siberia has featured the most prominent wildfire escalation during the past two decades, which is closely related to hydrological drought with decreasing rainfall and drying soil under a fast‐warming Arctic. Furthermore, fire‐emitted aerosols compound the increasing wildfires via serving as cloud condensation nuclei and suppressing precipitation, forming self‐amplifying feedback. As the Arctic warming is projected to continue, wildfires are estimated to more than double by the end of this century. This work highlights the great importance of fire risk management based on a fundamental scientific understanding of the complex climate system.

Spatio-Temporal Analysis of Wildfire Regimes in Miombo of the LevasFlor Forest Concession, Central Mozambique

Wildfires are an intrinsic and vital driving factor in the Miombo ecosystem. Understanding fire regimes in Miombo is crucial for its ecological sustainability. Miombo is dominant in Central Mozambique, having one of the highest fire incidences in the country. This study evaluated the spatio-temporal patterns of fire regimes (intensity, seasonality, frequency and fire return interval) in the LevasFlor Forest Concession (LFC), Central Mozambique using remotely sensed data from 2001 to 2022. We conducted hotspot spatial statistics using the Getis-Ord Gi* method to assess fire distribution and patterns. The results revealed that 88% of the study area was burnt at least once from 2001 to 2022, with an average burned area of 9733 ha/year (21% of LFC’s total area). Fires were more likely to occur (74.4%) in open and deciduous Miombo types. A total of 84% of the studied area, burned in a range of 4 to 22 years of fire return interval (FRI) over the 21 assessed. Only 16% of the area was affected by high to very high FRI (1 to 4 years), with an average FRI of 4.43 years. Generally, fires are more frequent and intense in September and October. These results highlight the usefulness of remote sensing in evaluating long-term spatiotemporal fire trends for effective fire management strategies and control measures in African savanna ecosystems.

Cross‐border dimensions of Arctic climate change impacts and implications for Europe

AbstractThe Arctic has warmed almost four times faster than the rest of the globe during the past four decades. This has led to multiple impacts in the Arctic such as the melting of glaciers and the Greenland ice sheet, sea ice retreat, permafrost thaw, altered species distribution and abundance, changes in hydrology and snow conditions, and altered wildfire regimes. These documented and projected impacts in the region can also propagate across borders, creating risks and opportunities requiring adaptation responses well beyond the Arctic. By undertaking a systematic literature review that uses a conceptual framework for cross‐border climate change impacts, we demonstrate how local impacts of the type described above, which are often analyzed separately in the literature, may initiate knock‐on effects that can be transmitted and transformed across borders. We illustrate examples of six categories of cross‐border risks resulting from this impact transmission and potentially requiring adaptation. These concern biophysical impacts, trade, infrastructure, finance, geopolitical relationships and human security and social justice. We examine potential adaptation options for responding to such cross‐border risks that are of relevance for Europe. The systemic approach taken in this paper promotes improved understanding of trade‐offs between potential benefits and risks, assists priority‐setting for targeting adaptation interventions, and can account for the important role of non‐climatic drivers in amplifying or dampening the cross‐border risks of climate change impacts in the Arctic.This article is categorized under: Trans‐Disciplinary Perspectives > Regional Reviews Assessing Impacts of Climate Change > Observed Impacts of Climate Change Assessing Impacts of Climate Change > Evaluating Future Impacts of Climate Change Vulnerability and Adaptation to Climate Change > Learning from Cases and Analogies

Changes in soil erosion caused by wildfire: A conceptual biogeographic model

Soil erosion rates after wildfire are strongly controlled by intrinsic properties such as topography, weather, climate, soil, and vegetation. These landscape and hydroclimatic properties are important in determining post-fire erosion rates; however, their influence on post-fire erosion and their interaction with the intensity of a wildfire remains uncertain. A key limitation in resolving this uncertainty is the lack of conceptual models and frameworks for organising data related to the geomorphic sensitivity of landscapes to wildfire. Our aim is to develop a framework for consolidating understanding of post-fire erosion in the context of hydroclimatic conditions which contribute to system states, for example soil and vegetation properties, and wildfire regime. The framework is developed around a simple conceptual model where the change in erosion due to wildfire is a product of change in runoff generation and sediment supply, which is strongly related to landscape net primary productivity (NPP). We hypothesised that geomorphic sensitivity to wildfire should vary as a unimodal humped relationship across a gradient of NPP, peaking at an intermediate level. To develop this framework and to test the hypothesis, we first review intrinsic soil and vegetation properties related to the supply and transport of sediment from burned and unburned hillslopes. Net primary productivity is systematically related to these intrinsic properties because it integrates many processes involved in soil and vegetation development. Empirical data indicate a trend in the change in surface runoff generation with NPP after wildfire, peaking at an NPP of approximately 15 Mg C ha−1 y−1. A simple model of fuel availability and soil heating are correlated with a similar “humped” trend in sediment supply. These results are consistent with our conceptual model, which indicates that sediment supply and runoff contribute towards a distinct peak in wildfire effects on erosion at an intermediate level of NPP. We propose that landscapes of intermediate NPP typically have the highest quantity of fuel available to burn, which cause large changes to the soil surface properties. Landscapes at intermediate NPP also tend to produce intrinsic soil and vegetation properties that promote erosion after wildfire. The interplay between these short and long-term landscape characteristics is strongest at intermediate levels of NPP. Our proposed biogeographic model of geomorphic sensitivity to wildfire was supported by erosion data from burned hillslope and zero-order catchments studies from a range fire-prone landscapes in Australia and North America. Our proposed conceptual model will help identify areas most vulnerable to post-fire erosion changes.

How will climate change and forest harvesting influence the habitat quality of two culturally salient species?

Boreal landscapes face increasing disturbances which can affect cultural keystone species, i.e. culturally salient species that shape in a major way the cultural identity of a people. Given their importance, the fate of such species should be assessed to be able to act to ensure their perennity. We assessed how climate change and forest harvesting will affect the habitat quality of Rhododendron groenlandicum and Vaccinium angustifolium, two cultural keystone species for many Indigenous peoples in eastern Canada. We used the forest landscape model LANDIS-II in combination with species distribution models to simulate the habitat quality of these two species on the territories of three Indigenous communities according to different climate change and forest harvesting scenarios. Climate-sensitive parameters included wildfire regimes as well as tree growth. Moderate climate change scenarios were associated with an increased proportion of R. groenlandicum and V. angustifolium in the landscape, the latter species also responding positively to severe climate change scenarios. Harvesting had a minimal effect, but slightly decreased the probability of presence of both species where it occurred. According to the modeling results, neither species is at risk under moderate climate change scenarios. However, under severe climate change, R. groenlandicum could decline as the proportion of deciduous trees would increase in the landscape. Climate change mitigation strategies, such as prescribed fires, may be necessary to limit this increase. This would prevent the decrease of R. groenlandicum, as well as contribute to preserve biodiversity and harvestable volumes.

Spatial and temporal monitoring of wildfires in Golestan province using remote sensing data

Wildfires are one of the most significant factors of ecosystem change. Knowing the wildfire regime (frequency, intensity, and distribution pattern) is essential in wildfire management. This research aims to analyze the spatiotemporal pattern of wildfires in Golestan in 2001-2021 using MODIS data, burned area product (MCD64A1). For this purpose, the annual and monthly frequency, as well as the trend of wildfires based on types of forest, pasture, and crop cover, were statistically analyzed. The local Moran pattern analysis method and kernel density function were used to analyze the spatial dynamics of wildfire. The results showed that 18,462 wildfires occurred in Golestan, the highest of which was in 2010, with 2,517 wildfires (13.8%). The lowest number of wildfires, with only 57 events (0.5%), was in 2001. Based on the local Moran model results and the kernel density function, the wildfires' extent and intensity were greater in the plains and foothills to the south and southeast of Golestan. The lowest extent and intensity of the wildfire corresponded to the eastern parts of the province. The frequency of wildfires was higher in the hot period of the year (spring and summer). However, the period of occurrence of wildfire and the peak of wildfire changes in different uses. The wildfire zones in June were wider and more intense than in other months. The frequency and spatial extent of wildfires in agricultural lands from May to July, pasture lands in July, August, and September, and forest lands in November and December were more than in other months. Weather conditions play a significant role in the occurrence of wildfire in the forest lands of Golestan. The results of this research help understand wildfire risk areas and provide a scientific basis for predicting and controlling wildfires and reducing carbon emissions related to them.

Predicting dynamics of wildfire regimes in Yunnan, China

In recent years, the rise in global warming has significantly increased forest fires, affecting the environment and economy. Predicting forest fire dynamics under climate change is now a crucial research field. To address this need, this study focuses on the impact of climate change on forest fires, with a particular focus on the fire dynamics in Yunnan Province. This study utilizes the RegCM regional climate model and the Canadian Fire Weather Index (FWI) to simulate and analyze forest fire dynamics in Yunnan Province from 2019 to 2033 under three climate scenarios: RCP2.6, RCP4.5, and RCP8.5. Findings indicate climate change will increase temperatures, alter humidity and wind speed, and reduce precipitation in Yunnan, extending the fire danger period, especially under RCP8.5 scenarios. The FWI values rise across Yunnan, particularly in the west under RCP2.6 and RCP8.5. The study concludes that future carbon emissions correlate with these changes, leading to more frequent, longer, and severe forest fires. This research is vital for managing and preventing forest fires in Yunnan, a region prone to such disasters.

Assessing changes in global fire regimes

BackgroundThe global human footprint has fundamentally altered wildfire regimes, creating serious consequences for human health, biodiversity, and climate. However, it remains difficult to project how long-term interactions among land use, management, and climate change will affect fire behavior, representing a key knowledge gap for sustainable management. We used expert assessment to combine opinions about past and future fire regimes from 99 wildfire researchers. We asked for quantitative and qualitative assessments of the frequency, type, and implications of fire regime change from the beginning of the Holocene through the year 2300.ResultsRespondents indicated some direct human influence on wildfire since at least ~ 12,000 years BP, though natural climate variability remained the dominant driver of fire regime change until around 5,000 years BP, for most study regions. Responses suggested a ten-fold increase in the frequency of fire regime change during the last 250 years compared with the rest of the Holocene, corresponding first with the intensification and extensification of land use and later with anthropogenic climate change. Looking to the future, fire regimes were predicted to intensify, with increases in frequency, severity, and size in all biomes except grassland ecosystems. Fire regimes showed different climate sensitivities across biomes, but the likelihood of fire regime change increased with higher warming scenarios for all biomes. Biodiversity, carbon storage, and other ecosystem services were predicted to decrease for most biomes under higher emission scenarios. We present recommendations for adaptation and mitigation under emerging fire regimes, while recognizing that management options are constrained under higher emission scenarios.ConclusionThe influence of humans on wildfire regimes has increased over the last two centuries. The perspective gained from past fires should be considered in land and fire management strategies, but novel fire behavior is likely given the unprecedented human disruption of plant communities, climate, and other factors. Future fire regimes are likely to degrade key ecosystem services, unless climate change is aggressively mitigated. Expert assessment complements empirical data and modeling, providing a broader perspective of fire science to inform decision making and future research priorities.

Simulated Future Shifts in Wildfire Regimes in Moist Forests of Pacific Northwest, USA

AbstractFire is an integral natural disturbance in the moist temperate forests of the Pacific Northwest of the United States, but future changes remain uncertain. Fire regimes in this climatically and biophysically diverse region are complex, but typically climate limited. One challenge for interpreting potential changes is conveying projection uncertainty. Using projections of Energy Release Component (ERC) derived from 12 global climate models (GCM) that vary in performance relative to the region's contemporary climate, we simulated thousands of plausible fire seasons with the stochastic spatial fire spread model FSim for mid‐21st century (2035–2064) under RCP8.5 emissions scenario for five northwestern pyromes. The magnitude of projected changes to burn probability, fire size, and number of fires varied among pyromes and GCMs. We projected the largest increases in burn probability and fire size in the cooler and wetter northern parts of the region (North Cascades, Olympics & Puget Lowlands) and Oregon West Cascades, with more moderate changes projected for the Washington West Cascades and Oregon Coast Range. We provide new insights into changing fire regimes characterized by the possibility of shifts toward more frequent and large fires (especially >40,000 ha), as well as shifts in seasonality, including more fires burning at the beginning of fall when extreme synoptic weather events have the potential to increase fire spread. Our work highlights the potential geographic variability in climate change effects in some of the most productive moist temperate forests of the world and points to a rapid acceleration of fire in the coming decades.

Drought-related wildfire accounts for one-third of the forest wildfires in subtropical China

The threat of wildfires to human safety and ecosystem services is widely known to increase due to climate change characterized by drought. In subtropical China, seasonal drought during the non-monsoon period contributes to increase of fire risk. However, both the relationship between drought and wildfire and the extent of drought effect are poorly understood. Based on satellite active fire detections and monthly drought metrics, we quantified the impact of drought on forest wildfire frequency in subtropical China during 2001–2020, using a Bayesian hierarchical modelling framework. We observed excess wildfire, defined here as above normal wildfire activity level, is significantly correlated to drought across subtropical China, and drought-wildfire relationship showed threshold behavior that the probability of excess wildfire increased significantly when the vapor pressure deficit (VPD) crossed 0.24 standard deviations of its long-term average. From 2001 to 2020, excess wildfire caused by drought accounted for approximately 31 % of the total number of forest fire points during the fire season (November to May). The drought-related excess wildfire was concentrated in 2007–2010 and 2014, and their spatial distribution showed a dipole between the western and eastern subtropical China in individual years. Moreover, we evaluated the spatiotemporal sensitivity of wildfire to drought by Bayesian model coefficients. There was higher sensitivity than average level of the entire region in 54 % of subtropical China, especially in northwestern Yunnan. Our results indicate that drought plays a dominant role on wildfire regime at the regional scale in subtropical China. As the drying trend intensifies in the future, wildfires will show different patterns due to the large differences in the sensitivity of wildfire to drought in subtropical China.

Fire regimes of the Southern Appalachians may radically shift under climate change

BackgroundIncreased drought due to climate change will alter fire regimes in mesic forested landscapes where fuel moisture typically limits fire spread and where fuel loads are consistently high. These landscapes are often extensively modified by human land use change and management. We forecast the influence of varying climate scenarios on potential shifts in the wildfire regime across the mesic forests of the Southern Appalachians. This area has a long history of fire exclusion, land use change, and an expanding wildland urban interface. We considered interactions among climate, vegetation, and anthropogenic influences to forecast future fire regimes and changes to the forest structure. We used climate scenarios representing divergent drought patterns (overall drought trend and interannual variability) within a process-based fire model that captures the influence of climate, fuels, and fire ignition on wildfire patterns and suppression.ResultsCompared to simulations using historical climate (1972–2018), future total burned area (2020–2100: 782,302.7 (716,655.0–847,950.3) ha) increased by 42.3% under high drought variability (1,134,888.4 (1,067,437.2–1,202,339.6) ha), 104.8% under a substantial increase in drought trend (1,602,085.7 (1,511,837.5–1,692,334.0) ha), and 484.7% when combined (4,573,925.0 (4,434,910.5–4,712,939.5) ha). Landscape patterns of fire exclusion and suppression drove the spatial variability of fire return intervals (FRI). Our projections indicate wide spatial variability in future fire regimes with some areas experiencing multiple fires per decade while others experience no fire. More frequent fires corresponded with increased oak prevalence and a reduction in the biomass of mesic hardwoods and maple; however, mesic hardwoods remained prevalent under all fire intervals because of their contemporary dominance.ConclusionsOur study illustrates how future drought–fire–management interactions and a history of fire exclusion could alter future fire regimes and tree species composition. We find that increasing trends in drought magnitude and variability may increase wildfire activity, particularly in areas with minimal fire suppression. In ecosystems where fuel moisture (and not load) is the standard limitation to fire spread, increased pulses of drought may provide the conditions for more fire activity, regardless of effects on fuel loading. We conclude the effects of climate and human management will determine the novel conditions for both fire regime and ecosystem structure.

202 years of changes in Mediterranean fire regime in Pinus nigra forest, Corsica

Wildfires are critical socio-ecological features in the Mediterranean basin. In a context of global changes (climate, land use), we questioned whether the wildfire regime was altered in the mountains of Corsica, France. Using tree-ring analysis of fire-scarred trees, we tested for changes in frequency, seasonality, and area. We hypothesized that the fire regime changed during the middle-20th century due to human activities, as observed elsewhere in the Mediterranean. We sampled fire-scarred trees, geolocated for mapping fire areas, in a forest of black pine (Pinus nigra laricio). The oldest fire was in 1684 but the fire chronology with adequate sample depth for analysis covered 202 years [1820–1921]. Between 1820–2012, 15 fires were recorded, 8 of which scarred at least 25% of the sampled trees. The mean fire interval was 14 years, corresponding to a high fire frequency with 4 major fires per century. Most fires occurred between 1931–1970. On average, about 50% of trees were scarred by fires before 1931, but this percentage decreased thereafter. The exception was the 2000 fire that impacted 100% of living trees. Mapping showed spatially heterogenous fire areas. These results match other Mediterranean studies showing longer fire intervals since the late-20th century, and wildfires generally occurred during the period of late-earlywood or latewood formation, i.e., summer or early autumn, which is the season of contemporary fires. Although fires were recurrent for more than 200 years with no change in the fire season, the regime changed twice in frequency. These changes likely result from a combination of land use and warmer summer conditions. While pines survived most past fires of low intensity through the last large fire in the 1970’s, the severe fire of 2000, following ca 30 years of fire suppression, killed large patches of mature trees. Such chronology provides rational arguments for black pine ecosystem management, notably to consider seeking to recover the sustainable fire regime of the 19th century, for instance by using prescribed fires to manage surface fuel.

The importance of habitat type and historical fire regimes in arthropod community response following large-scale wildfires.

Novel wildfire regimes are rapidly changing global ecosystems and pose significant challenges for biodiversity conservation and ecosystem management. In this study, we used DNA metabarcoding to assess the response of arthropod pollinator communities to large-scale wildfires across diverse habitat types in California. We sampled six reserves within the University of California Natural Reserve System, each of which was partially burned in the 2020 Lightning Complex wildfires in California. Using yellow pan traps to target pollinators, we collected arthropods from burned and unburned sites across multiple habitat types including oak woodland, redwood, scrub, chamise, grassland, forest, and serpentine habitats. We found no significant difference in alpha diversity values between burned and unburned sites; instead, seasonal variations played a significant role in arthropod community dynamics, with the emergence of plant species in Spring promoting increased pollinator richness at all sites. When comparing all sites, we found that burn status was not a significant grouping factor. Instead, compositional differences were largely explained by geographic differences, with distinct communities within each reserve. Within a geographic area, the response of arthropods to fire was dependent on habitat type. While communities in grasslands and oak woodlands exhibited recovery following burn, scrublands experienced substantial changes in community composition. Our study highlights the importance of examining community responses to wildfires across broad spatial scales and diverse habitat types. By understanding the nuanced dynamics of arthropod communities in response to fire disturbances, we can develop effective conservation strategies that promote resilience and maintain biodiversity in the face of increasing wildfire frequency and severity driven by climate change.

Influence of irregular shelterwood treatments on intensity and severity after a large wildfire in lodgepole pine stands: A case study from the interior British Columbia.

Climate change has significantly impacted the wildfire regimes in lodgepole pine forests, resulting in prolonged fire seasons and altered fire behaviour. In North America, fire patterns have shifted towards more frequent and severe wildfires after a century of fire suppression. In response, silviculture practices in fire-prone areas should aim to restore diverse forest structures that are resistant or resilient to wildfires. In Western Canada, where forestry is a key industry, interest in seeking silvicultural solutions for promoting forest resilience to wildfires has increased following the devastating wildfire seasons between 2017 and 2023. Irregular shelterwood, a silvicultural system with a relatively short history of implementation in British Columbia, has been deployed in ecologically sensitive areas to promote structural heterogeneity and meet management goals for biodiversity and wildlife values. Although the impacts of irregular shelterwood on wildlife habitat and abundance have been well studied, the interaction between wildfire and the stand structure created by irregular shelterwood remains poorly understood. To understand the effectiveness of the irregular shelterwood in building wildfire resilience, we present a study of a lodgepole pine stand that was treated with irregular shelterwood and partially burned in a wildfire in 2017. This study collected ground fuel, canopy fuel, and tree data from four stand types (irregular shelterwood treated-burnt, treated-unburnt, untreated-burnt, and untreated-unburnt) and analyzed the difference in char height and fire-induced mortality between burnt and unburnt conditions, with irregular shelterwood treatment being a variable. The results demonstrated reduced wildfire effect in the irregular shelterwood stand in this region of British Columbia. This observation was made at a stage where the openings have not been colonized by regeneration. This case study provides valuable insights into the effectiveness of irregular shelterwood in mitigating wildfire risk, and proposes a potential silviculture solution to promote forest resilience to wildfire.

Enhancing infrastructure resilience in wildfire management to face extreme events: Insights from the Iberian Peninsula

Factors such as human activity and climate change are contributing to an increase in the frequency and intensity of wildfires. This problem has challenged society’s knowledge, response capacity, and resilience, revealing its inadequacy to cope with the new wildfire regime characterized by extreme wildfire events (EWE). Policies on wildfire management mainly focus on suppression and managing emergencies, which may be insufficient to reduce EWE’s incidence and cope with its impact. Consequently, there is a lack of tools to support decision-making in wildfire management in other important aspects, such as prevention and protection. This study examines global wildfire policies specifically in the Iberian Peninsula (Portugal and Spain), including cross-border policies. A GIS-based tool to evaluate different normal and extreme wildfire management policies is applied to a cross-border case study, paying attention to the impact on critical land-based transport systems. A relevant outcome of the tool application is that suppression must be complemented with other wildfire management strategies in the analyzed area. The gained insights can help stakeholders to improve decision-making in wildfire management to successfully address EWE.