1 IMPLICATIONS ON ECOSYSTEM SERVICES Analyzing changes in wildfire likelihood and intensity in Mediterranean areas: a case study from central Sardinia, Italy Salis M. 1,2* , Alcasena F. 2 , Ager A.A. 3 , Casula F. 2 , Arca B. 4 , Bacciu V. 2 , and Spano D. 1,2 1 University of Sassari, Department of Science for Nature and Environmental Resources (DIPNET), Sassari, Italy, 2 Euro-Mediterranean Center for Climate Changes (CMCC), IAFENT Division Sassari, Italy. 3 USDA Forest Service, Pacific Northwest Research Station, Western Wildland Environmental Threat Assessment Center, USA. 4 National Research Council (CNR), Institute of Biometeorology (IBIMET), Sassari, Italy. * Corresponding author: miksalis@uniss.it Abstract In this work, we used mechanistic wildfire simulation to examine how ignition patterns, land use, weather, and fuels affect wildfire likelihood and intensity. The study area was located in central Sardinia, Italy and encompassed about 680 km 2 . We simulated 10,000 wildfires for each combination of the input variables using the MTT algorithm as implemented in FlamMap and Randig. The range of values for the input variables was chosen from historical weather data to represent realistic conditions within the study area. Wildfire outputs analyzed included flame length, burn probability, and fire size. The results suggested that the most important role in influencing burn probability and flame length for the conditions studied was fuel moisture. Land use change was also responsible for increases in burn probability and flame length, and resulted from the expansion of unmanaged Quercus spp. forests and Mediterranean shrubs into areas that were traditionally managed grasslands and crops. Wind direction and ignition locations had a substantial influence on spatial patterns in fire size and burn probability, with a relatively minor effect on fire intensity. Wind speed had a notable effect on the shape of fire perimeters, and also resulted in increased burn probability. K e y w o r d s : Historical changes, fire modeling, wildfire likelihood and intensity, Mediterranean areas IMPLICATIONS ON ECOSYSTEM SERVICES 685