## 3 Results
### Fine Dead Fuel Map  
According to performance metrics, the best model (lowest RMSE and highest R\({}^{2}\)) was used to estimate and map 1-h fuel load in a pilot area of the Apulia region. Figure 6 shows the 1-h fuel load (t/ha) map estimated by the RF model in the administrative area of Martina Franca. The 1-h fuel load values ranged from a low of 0.01 t/ha to a high of 0.53 t/ha. Figure 5: Variable importance of the Random Forest model for 1-h fuel load estimation measured by (**A**) the percentage increase in Mean Squared Error (%IncMSE) and (**B**) increase in node purity (IncNodePurity). Abbreviations are: Easternness = Easternness of each plot, VH = VH polarization, Slope = Slope in each plot, Elevation = Elevation of each plot, NDVI = Normalized Difference Vegetation Index, Landcover_class = Land-cover class in each plot, Vegetation_cover = Vegetation cover, Canopy_cover = Canopy cover, and CHM_maxq = Canopy Height Model 95 th percentile. The highest 1-h fuel load predicted (0.26-0.53 t/ha) was recorded in the south-west part of the pilot area where deciduous forests can be found. Likewise, the lowest estimated 1-h fuel load (0.01-0.14 t/ha) was found in the south-east portion of the pilot area, mostly covered by meadows and pastures. Table 5 represents the distribution of each land-cover category in terms of surface area (ha) within the 1-h fuel load classes as estimated by the RF model. Among the land-cover classes, the deciduous forest (6171 ha) and sclerophyllous vegetation (803.55 ha) areas covered most of the entire pilot area, whereas mixed woods (22.27 ha), coniferous woods (67.62 ha), and natural recolonization areas (11.03 ha) were less representative. As the number of trees increased, the 1-h fuel load increased as well. More than 85% of the pastures and meadows (with or without trees) and natural recolonization areas recorded 1-h fuel load values between 0.01 t/ha and 0.14 t/ha and rarely exceeded 0.18 t/ha. The 1-h fuel load values for deciduous forests were highly variable and approximately between 0.14 t/ha and 0.53 t/ha. However, the highest 1-h fuel load values (0.26-0.53 t/ha) were found almost exclusively in deciduous forests. The components of the Mediterranean scrub (brush, shrubs, and sclerophyllous area) produced \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Land-Cover Class**} & \multicolumn{4}{c}{**1-h Fuel Load (t/ha)**} & \multicolumn{2}{c}{**Total Area**} \\ \cline{2-7}  & **0.01–0.14** & **0.14–0.18** & **0.18–0.21** & **0.21–0.26** & **0.26–0.53** & **(ha)** \\ \hline
**Coniferous** & 2.60 (3.85\%) & 19.26 (28.48\%) & 15.68 (23.19\%) & 26.99 (39.91\%) & 3.09 (4.57\%) & 67.62 \\
**Deciduous** & 470.74 (7.63\%) & 1294.65 (20.98\%) & 1465.94 (23.76\%) & 1433.25 (23.23\%) & 1506.44 (24.41\%) & 6171.02 \\
**Mixed** & 0.91 (4.09\%) & 4.31 (19.35\%) & 4.38 (19.67\%) & 6.62 (29.73\%) & 6.05 (27.17\%) & 22.27 \\
**Bush or Shrubs** & 104.34 (78.33\%) & 16.21 (12.17\%) & 4.06 (3.05\%) & 7.55 (5.69\%) & 1.04 (0.78\%) & 133.2 \\
**Sclerophyllous** & 532.45 (66.26\%) & 180.15 (22.42\%) & 32.70 (4.07\%) & 48.64 (6.05\%) & 9.61 (1.20\%) & 803.55 \\
**Vegetation** & 73.92 (89.02\%) & 6.09 (7.33\%) & 1.28 (1.54\%) & 1.62 (1.95\%) & 0.12 (0.14\%) & 83.03 \\
**Meadows or Pastures** & 331.76 (97.53\%) & 5.06 (1.49\%) & 1.90 (0.56\%) & 1.42 (0.42\%) & 0.02 (0.01\%) & 340.16 \\
**Natural Recolonization** & 9.56 (86.67\%) & 0.65 (5.89\%) & 0.46 (4.17\%) & 0.31 (2.81\%) & 0.05 (0.45\%) & 11.03 \\
**Areas** & & & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Distribution of land-cover categories in terms of surface area (ha) within the 1-h fuel load classes as estimated by the Random Forest model in the pilot area of Martina Franca. Figure 6: Fine dead fuel map generated by the Random Forest model across a pilot area of the Apulia region (southem Italy). Fuel ranges are expressed in quantiles. A zoomed portion (**left**) of the pilot area without (**A**) and with (**B**) the 1-h fuel load map overlay.