Mapping wildfire defence priorities in the Pyrenees landscapes: Sant Julià de Lòria case study (Andorra)

(ENG) Along last centuries, the Pyrenean landscape has been dominated by an equilibrium between the traditional socio-economic activities (cattle, agriculture and forestry) and the natural dynamics events (avalanche, flash floods, landslides). However, during the last 50 years a new paradigm has taken place as a consequence of a generalized and unprecedented land use change, motivated by the loss of traditional activities toward the tourism and business economy. In addition, forestland have experienced an increase on the demand of its social services and the wildland urban interface as well bringing with it an anthropogenic ignition probability rise, even more within the climate change context. This situation could involve worst wildfires seasons in terms of frequency and severity at the Pyrenean landscape level. Wildland forest management and protection program budgets are limited, and managers are requesting help in finding ways to objectively assign their limited protection resources based on the intrinsic environmental characteristics of the site and the available firefighting resources. A Defence Priority Index against wildfire, integrating information on the historical fire risk (Historical Risk Index), the potential fire behaviour (Potential Fire Behaviour Index), the potential ignition risk caused by human activities (Potential Risk Index), the goods and forest services damages due to fire (Potential Damage Index) and the fire suppression difficulty (Suppression Difficulty Index), provides managers with fundamental information for strategic planning and development of tactical operations to protect the natural values and human infrastructures across the landscape. This methodology has been applied for first time in Pyrenees region, at province level of Sant Julià de Lòria, Principality of Andorra, having been calculated so far the first three indices, and the others are still being implemented. Preliminary results showed two significant historical fire scenarios (winter ends and summer), both with a low to moderate fire behaviour risk. According to these results, the highest defence priority was found on the wildland urban interface surrounded by evergreen oak formations. In these locations, preventive silvicultural treatments focused on vegetation are strongly recommended in order to reduce the flame length and the rate of spread, as well as self-protection guidelines to perform and improve the owner's resilience