Abstract ID: 3.10441 | Accepted as Talk | Talk/Oral | TBA | TBA

Insect outbreaks, windthrows and wildland fires are among the most relevant natural disturbances affecting forested ecosystems worldwide. The storm Vaia occurred in October 2018 affected many Norway spruce (Picea abies (L.) Karst.) forests in the Eastern Italian Alps. Successively, a severe outbreak of bark beetle (Ips typographus) involved the same area leading to economic and social issues. The interaction between windthrows, bark beetle outbreaks and alterations in wildfire behaviour is scarcely investigated, especially for Italian forests. This research aimed to detect the effects of windstorm and bark beetle proliferation in the alteration of wildfire behaviour in two forested areas (Veneto region, northern Italy), respectively affected by windstorm (first scenario) and bark beetle proliferation (second scenario). The semi-empirical FlamMap model was used to simulate fire behaviour, and Airborne Laser Scanning (ALS) data was processed to derive the spatial distribution of forest attributes and fuels within each study area. 5 meters-resolution Digital Terrain Models (DTMs), Canopy Height Models (CHMs), topographic data and forest metrics were extracted for each scenario, to model alterations of wildfire behaviour over time. The contribution of storm Vaia and bark beetles in altering wildfire behaviour was explored using ALS point clouds acquired before and after the occurrence of the two natural disturbances. Differences in Rate of Spread (RoS), flame length (FL), midflame windspeed (WS) and arrival time (AT) were assessed looking at the first case study (windthrown forest), while differences in RoS and Burn Probabilities (BP) were investigated concerning the second one (bark beetle-affected forest). An increase of RoS, FL, and WS greater than 30 m/min, 3 m and 1.1 m/s were estimated in windthrown areas, as well as a decrease of AT greater than 30 min. An increase in RoS over 25m/min and in BP greater than 0.5 were estimated in forested areas affected by bark beetle outbreak, confirming the key role of windstorm and Ips typographus in altering the spatial behaviour of potential wildfires. This type of analysis could serve as a starting point to explore similar issues using ALS data and mathematical models, aiming to propose effective management solutions for forests affected by different natural disturbances.