Fig. 1. Eight controlled burning sites in southern Finland marked with black dots. The test sites ‘Kivimäensalo’, ‘Liesjärvi’, ‘Pyhä-Häkki’, ‘Nuuksio’, and ‘Seitseminen’ were burned in 2021, whereas ‘Evo’, ‘Ruunaa’, and ‘Salamajärvi’ in 2022. All the test sites are located within national parks or protected areas.

Fig. 2. The test site ‘Evo’ two months before (left) and a few days after (right) the controlled burning.

Fig. 3. Pre-fire point clouds (left) were aligned with post-fire point clouds (right) using a 3D transformation derived from common tie points, e.g., the large black dots in the figure. The tie points were manually extracted from the point clouds.

Fig. 4. Three 1 × 1 m cells from the test site ‘Evo’, classified as ‘burned’ by the developed classification method but as ‘unburned’ through visual interpretation (a), and three 1 × 1 m cells from the test site ‘Kivimäensalo’ classified as burned both by the developed method and visual interpretation (b). Pre-fire (green) and post-fire (red) point clouds are overlaid. View larger in new window/tab.

Fig. 5. Spatial distribution of 1 × 1 m cells classified as ‘burned’ and ‘unburned’ for each controlled burning site. Test sites are oriented in a north-south direction. 1 = Kivimäensalo, 2 = Liesjärvi, 3 = Pyhä-Häkki, 4 = Nuuksio, 5 = Seitseminen, 6 = Evo, 7 = Ruunaa, 8 = Salamajärvi.

Fig. 6. Ground vegetation volumes (including tree stems below 2 m) before and after controlled burnings (a), and total changes (black) with burned (red) and growth (green) volumes (b) at a resolution of 0.1 m. Negative values indicate a decrease and positive values an increase in ground vegetation volume.

Fig. 7. Variation in ground vegetation volume changes in 1 × 1 m cells classified as ‘burned’ and ‘unburned’ in the controlled burning sites. The line in the box center represents the median value; the box represents the middle 50% of the cell values; 25% of the values fall below the lower quartile (bottom of the box), and 75% fall below the upper quartile (top of the box); whiskers represent minimum and maximum cell values. Outliers (i.e., 0.35% of the observations both above and below the whiskers) are not shown in the figure to enhance the display of data distribution and variability. View larger in new window/tab.