Modeling the effects of different fuel treatment mosaics on wildfire spread and behavior in a Mediterranean agro-pastoral area

Wildfire spread and behavior can be limited by fuel treatments, even if their effects can vary according toa number of factors including type, intensity, extension, and spatial arrangement. In this work, wesimulated the response of key wildfire exposure metrics to variations in the percentage of treated area,treatment unit size, and spatial arrangement of fuel treatments under different wind intensities. Thestudy was carried out in a fire-prone 625 km2 agro-pastoral area mostly covered by herbaceous fuels, andlocated in Northern Sardinia, Italy. We constrained the selection of fuel treatment units to areas coveredby specific herbaceous land use classes and low terrain slope (<10%). We treated 2%, 5% and 8% of thelandscape area, and identified priority sites to locate the fuel treatment units for all treatment alternatives.The fuel treatment alternatives were designed create diverse mosaics of disconnected treatmentunits with different sizes (0.5e10 ha, LOW strategy; 10e25 ha, MED strategy; 25e50 ha, LAR strategy); inaddition, treatment units in a 100-m buffer around the road network (ROAD strategy) were tested. Weassessed pre- and post-treatment wildfire behavior by the Minimum Travel Time (MTT) fire spread algorithm.The simulations replicated a set of southwestern wind speed scenarios (16, 24 and 32 km h1)and the driest fuel moisture conditions observed in the study area. Our results showed that fuel treatmentsimplemented near the existing road network were significantly more efficient than the otheralternatives, and this difference was amplified at the highest wind speed. Moreover, the largest treatmentunit sizes were the most effective in containing wildfire growth. As expected, increasing thepercentage of the landscape treated and reducing wind speed lowered fire exposure profiles for all fueltreatment alternatives, and this was observed at both the landscape scale and for highly valued resources.The methodology presented in this study can support the design and optimization of fuelmanagement programs and policies in agro-pastoral areas of the Mediterranean Basin and herbaceoustype landscapes elsewhere, where recurrent grassland fires pose a threat to rural communities, farmsand infrastructures.