Wildfires are complex disturbances and regular in Mediterranean ecosystems. Climate change is increasing the frequency and severity of fire disruption. The distribution of forests and variations in species determine the fuel composition and accumulation that will affect fire intensity, burn severity, and wildfire expansion patterns._x000D_
This study aims to measure forest combustion energy, above ground biomass (AGB), soil organic matter (SOM) and species distribution in an unmanaged forest 28 years after a historical wildfire. The research site is located in the Cadiretes massif, Girona, NE Spain. The area was formerly a plantation of Pinus pinaster and Quercus suber L. that was affected by a wildfire in 1994, with no post-fire management. The study area has three research areas affected by different levels of fire severity: Low Severity (LS), High Severity (HS) and an unburnt Control area (C). Three UAV (drone) flights were developed in 2022, capturing high-resolution data of spectral indices and vegetation biomass structure using RGB and multispectral cameras, a LiDAR (approx. 270 points/m²) device and an associated RTK GPS for ground control (Σx, Σy and Σz approx. 0.01m). Forest vegetation inventories were also conducted in spring 2022 and compared with UAV data._x000D_
Our initial findings suggest that the potential energy released through combustion has increased for both LS and HS locations due to biomass accumulation since 1994. The control area presented more AGB and SOM in comparison to LS and HS after 28 years. Differently, our forest inventory data shows that biodiversity for the LS location is higher than for the other (HS and C) locations, showing 19, 14 and 9 different plant species for LS, HS and C, respectively. The risk of wildfire is greater in HI and C than in LI due to fuel continuity and density, caused particularly by the presence of highly flammable shrub species in the HS area and dead biomass accumulated in the control area._x000D_

Eduardo A. Garcia-Braga, Antonio Peñalver-Alcalá, Joaquim Farguell, Mariano Moreno De las Heras, Xavier Úbeda
GRAM (Grup de Recerca Ambiental Mediterrània), Department of Geography, University of Barcelona, Barcelona, Spain.

 
ID Abstract: 655