Land use changes and temporal patterns of wildfire probability and intensity in Northern Sardinia, Italy

Wildfire spread and behaviour are affected by complex and non-linear relationships among many factors including weather, fuels, topography, and ignition patterns. During the last decades, Mediterranean areas have been affected by relevant modifications in the economic and social systems that have often produced transformations of the original landscape due to anthropization processes and land use changes. Socio-economic changes have led to an increase of the anthropic pressure in urban and coastal areas and to a progressive abandonment of farming and agro-forestry activities. This has favored substantial increases in fuel loading and continuity, especially where agricultural areas and pastures have been converted to shrublands and woodlands. Throughout most of Mediterranean coastal areas, potential fire risk for villages, tourist resorts, other human activities and people is really high, particularly in summer when human presence increases, extreme weather conditions can occur, and vegetation is highly flammable. Therefore, developing planning policies is essential for implementing strategies to prevent and reduce wildfire risk in these areas. Recently, several authors showed that the analysis of trends in both anthropization processes and land use changes and the evaluation on their impacts on fire occurrence and behavior are crucial for reducing and preventing fire risk and making decisions on future land use planning. Tracking past and recent land use change trends allows to minimize their impact and to provide information for long-term land use planning and natural resource management. The prediction of burn probability and intensity by the use of wildfire simulators is a valuable method to capture the large variability of fire spread and behavior produced by weather and fuel conditions, especially when extreme weather conditions, and their effects on fuel characteristics, leads to large fires. In this study, we focus on analyzing and evaluating the temporal evolution, over the period 1954-2000, of land use and urban areas in two coastal regions located in North Sardinia, Italy, both characterized by large tourism development during the last fifty years. We used wildfire simulation to examine how different level of urbanization, land use and fuel type changes, can affect fire likelihood and intensity. In particular, simulations were conducted using the landscape characteristics existing in the year 1954, 1977 and 2000. The experimental data showed that the land use change observed throughout the study period (from 1954 to 2000) determined a reduction of burn probability in the last time step (2000), while limited differences were observed from 1954 to 1977.