ICFBR2022 - 3rd International Conference on Fire Behavior and Risk

Aline Oliveira apresentou, no dia 03/05, a comunicação "Are native forests an alternative to prevent wildfires in the WUI in Central Portugal?", veja abaixo um resumo do que foi apresentado:

The expansion of the 2017 mega-fires in Portugal was observed to be locally halted by native broadleaf forest patches. Here we present spatial simulation scenarios of fire behavior to assess whether native broadleaf forest cover mitigates fire spread during extreme wildfire conditions in wildland-urban interface (WUI) areas around Industrial Zones (IZs).

Our particular objective was to ascertain whether these forests could be an alternative land use in the 100-m management buffer around industries (mandatory management buffer, as per Portuguese Decree-Law n. º 82/2021). To this end, we combined a series of fire behavior variables and used real-world data from the 2017 fires. to try to reproduce, through spatial modelling, those same fires in the broadleaved forest Mata da Margaraça (Figure 1) and in the IZs: Oliveira do Hospital, Mira, and Tocha, located in the center of Portugal. Subsequently, we adopted the same fuel model and canopy cover (81-100%) from Mata da Margaraça to create alternative fire behavior scenarios in 100 m and 500 m management ranges around IZs. Thus, we were able to assess whether a hypothetic conversion to native forest that has greater canopy cover would prevent fire to propagate into the IZs. All simulations were carried out within a 5-km buffer from the IZs to capture fire dynamics.

Our results suggest that broadleaved forest cover can reduce fireline intensity and rate of spread around IZs up to 20 and 8 times, respectively, on average. This reduction is more drastic as the surrounding area covered by broadleaves increases from 100 m to 500 m. Our results support the need to discuss forest management in Portugal to efficiently prevent intense fires in the WUI encouraging the restoration of native forests and wider green fuel breaks.

Joaquim Sande Silva apresentou no dia 04/05 o trabalho intitulado "Effect of Fuel Management and Forest Composition on Fire Behavior in Central Portugal", veja abaixo um resumo do que foi apresentado:

In Southern Europe, Portugal has registered the largest number of wildfires and the second largest burned area. Fuel Breaks are one of the ways of prevention and containment of wildfires present in legislation (Decree-Law n. º 82/2021). However, the measures and standards that regulate Fuel Breaks lack scientific validation to assess their effectiveness.

This study aims to evaluate the effect of fuel management of Fuel Breaks and the effect of forest type, on surface fire behavior. Thirty pairs of Managed Areas vs. Non-Managed Areas were sampled, distributed throughout the Central Region of Portugal, in ten eucalyptus stands, ten maritime pine stands, ten mixed stands of eucalyptus and other species. Field data, including loads and structure of fuels, fuel moisture and micrometeorological information, were collected and used to develop fuel models and perform surface fire behavior simulations in Behave Plus 6 Beta.

The results show that only one third of the statistical tests showed significant differences (Table 1) on surface fire behavior between Managed and Unmanaged areas. Likewise, only one statistical test (out of 12) showed significant differences in fire behavior between the three types of stands. Our results show that the reduction in fuel load and depth in Managed areas was annulated by the more severe meteorological conditions (stronger wind speed and lower moisture) observed in these areas. However, it should be taken into consideration that this study only assesses surface fire. Despite these results, Fuel Breaks are an important instrument of prevention and containment of wildfires, by allowing better access of means of combat and decreasing the likelihood of ignition from, for example, roads and power transmission lines. On the other hand, different results would probably be obtained by including crown fire simulations and more severe weather scenarios