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Despite growing interest in developing extensive fuel treatment programs to prevent catastrophic wildfires in the Mediterranean region, there is little information on the projected effectiveness of fuel treatments in terms of avoided exposure and risk. In Portugal, a fuel management plan aiming to prevent loss of lives, reduce large fires (500 ha), and reduce annual burned area is under implementation, with particular emphasis on the nation-wide fuel break network (FBN). In this study, we evaluated the effectiveness of the planned FBN in terms of meeting fire management objectives, costs, and benefits. We first estimated the overall effectiveness of the FBN at intersecting modeled large fires (500 ha) and at reducing exposure to protected areas and residential buildings using wildfire simulation modeling. Then, the fuel break burn-over percentage, i.e. the percentage of fires that are not contained at the FBN, was modeled as a function of pre-defined flame length thresholds for individual FBN segments. For the planned FBN, the results suggested a potential reduction of up to 13% in the annual burned area due to large fires (ca. 13,000 ha), of up to 8% in the annual number of residential buildings exposed (ca. 100 residential buildings), and up to 14% in the annual burned area in protected areas (ca. 2400 ha). The expected burn-over percentage was highly variable among the segments in response to estimated fire intensity, and an average decrease of 40% of the total benefits was estimated. The most important fuel breaks typically showed a higher percentage of fire burn-over, and hence reduction in effectiveness. We also showed that the current implementation of FBN follows a random sequence, suboptimal for all objectives. Our results suggest that additional landscape-scale fuel reduction strategies are required to meet short-term national wildfire management targets.

Despite the abundant firefighting resources deployed to reinforce the fire exclusion policy, extreme events continue to cause substantial losses in Mediterranean regions. These catastrophic wildfires question the merely-reactive response, while science-based decision-making advocates for a paradigm shift towards a long-term solution to coexist with fire. Comprehensive management solutions integrate multiple efforts to minimize the number of escaped wildfires in fire ignition hotspots, restrict large fire spread across the landscape, and prevent losses to valued resources and assets. This study develops a wildfire management zone (WMZ) delineation framework to inform decision-making in fire-prone Mediterranean landscapes. First, we combined modeling outcomes of wildfire occurrence, initial attack success, and wildfire transmission to communities to segment the landscape in WMZ blocks. We assumed the worst-case scenario in terms of fire simultaneity and weather conditions to implement the models. The geospatial outcomes were assembled and classified into four primary archetypes, and we then designated the most suitable risk mitigation strategies for each management unit. The WMZs included (1) comprehensive management, (2) human ignition prevention, (3) intensive fuel management, and (4) fire reintroduction areas. Finally, we downscaled within zones to assign specific management prescriptions to the different areas. The results were presented in a set of cross-scale maps to assist in designing risk management plans and raise social awareness. The methodological framework developed in this study may be valuable to help mitigate risk in fire-prone Mediterranean areas, but also in other regions in which similar total suppression policies fail to reduce catastrophic wildfire losses. This work has been financed by the Spanish Ministry of Economy and Competitiveness, postdoctoral ‘Juan de la Cierva Formación’ research grant (FJCI-2016-31090) awarded by Marcos Rodrigues. The work was partially funded by the projects FirEUrisk “DEVELOPING A HOLISTIC, RISK-WISE STRATEGY FOR EUROPEAN WILDFIRE MANAGEMENT”. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101003890; and CLIMARK “Forest management promotion for climate mitigation through the design of a local market of climatic credits” (LIFE16 CCM/ES/000065).

The impact of rural fires in the Mediterranean Basin is rapidly increasing as extreme fire seasons become the new norm. Following the catastrophic 2017 fire season in Portugal, a national-scale fuel break network (FBN) was designed by the Rural Fire Management Agency (AGIF), and the implementation of fuel treatments along the fuel break network was initiated. Despite growing interest in developing extensive fuel treatment programs to prevent catastrophic wildfires and reduce exposure and risk in the Mediterranean region, there is still little information on the effectiveness of such programs. The Portuguese nation-wide FBN is part of the fuel management plan aiming to prevent loss of lives, reduce large fires (> 500 ha) and decrease annual burned area is under implementation. In this study, we used Monte Carlo methods and mechanistic wildfire spread modeling to simulate plausible wildfire events in Portugal. The modeling system was calibrated to local fuels and weather at monthly time steps. We then examined how the proposed fuel break network was intersected by simulated fires and the effectiveness in terms of protecting residential buildings and designated protected areas. The fuel breaks burn over percentage, i.e. the percentage of fires that are not contained by the FBN was modeled as a function of pre-defined flame length thresholds for individual FBN segments. From these outputs, we were able to compare priorities as determined from the simulation system to the FBN implementation plan by AGIF. Our results show that the full implementation of FBN can provide tactical opportunities for rural fire suppression and containment. The FBN has the potential to reduce up to 1) 13% in the annual burned area due to large fires; 2) 8% in the annual number of residential buildings exposed, and 3) 14% in the annual burned area in protected areas. However, the results also reveal that in many cases the FBN intersects fires after they have grown to over 500 ha, hence representing minimal potential in preventing large fires. The expected burn-over percentage was highly variable among the segments. An overall average decrease of 40% of the total benefits was estimated, with the most important fuel breaks typically showing a high percentage of fire burn over. Our results suggest that additional landscape-scale fuel reduction strategies are required to meet short-term national wildfire management objectives.

This research shows the potential use of cross-boundary fire modeling systems at the pan-European level. Despite the growing interest in building fire-resilient cultural landscapes, European Union (EU) level efforts have been reactive and focused on early detection, fire propagation monitoring, and perimeter mapping rather than predicting where the disaster can potentially occur to develop a comprehensive wildfire management strategy. We propose a modeling system that integrates wildfire occurrence models and observed fire-weather scenarios with a fire spread model to generate the probabilistic risk components, i.e., wildfire likelihood and hazard estimates. We selected four NUTS-2 level administrative division pilot sites from different fire-prone countries to implement the modeling system. The European-level pyromes were first delineated based on ecoregions and historical wildfire activity. We then generated human and lightning wildfire occurrence models to display the ignition points. Remote sensing products were used to derive fire spread modeling spatial input data such as surface fuels and canopy metrics. Global atmospheric products were used to calculate the fuel moisture content with physical models and determine the most frequent wind scenarios for each pyrome. We then used the Minimum Travel Time algorithm to model the fire footprints that correspond to 10,000 years or synthetic iterations. This modeling approach accounted for the spatial variation of ignition locations and the changing weather conditions across the different pyromes within each pilot site. The modeling results include the annual burn probability and fire intensity rasters, and fire perimeter vector outputs. Modeled burn patterns showed a close agreement with observed fire size distributions. We compared this modeling system with previous works to explain why stochastic fire modeling is essential to assess wildfire exposure of natural values at risk and human communities. Our results may help predict future catastrophic fires and provide quantitative estimates to identify high-priority management areas within vast regions. The probabilistic predictions generated in this work represent the foundation for developing long-term adaptation strategies to better coexist with fire. This work is also a demonstration of how this modeling system is replicable in any European country.

We examined the financial efficiency and effectiveness of landscape versus community protection fuel treatments to reduce structure exposure and loss to wildfire on a large fire-prone area of central Idaho (USA). The study area contained 63,707 structures distributed in 20 rural communities and resorts, encompassing 13,804 km