Airborne laser scanning reveals large tree trunks on forest floor

Fallen trees decompose on the forest floor and create habitats for many species. Thus, mapping fallen allows identifying most valuable areas regarding biodiversity, especially in boreal forests, enabling well-focused conservation restoration actions. Airborne laser scanning (ALS) is capable of characterizing forests underlying topography. However, its potential detecting under varying conditions not yet well understood. ALS-based tree detection methods could improve our understanding spatiotemporal characteristics dead wood over large landscapes. We developed tested an automatic method individual from ALS point cloud with a density 15 points/m2. The presented detects using iterative Hough line delineates around detected lines region growing. Furthermore, we conducted detailed evaluation how performance impacted by structure vegetation them. results this study showed that can be high accuracy old-growth forests. In contrast, young managed stands proved challenging. was able to detect 78% largest (diameter at breast height, DBH > 300 mm), whereas 30% all 100 mm were detected. positively correlated both size living surrounding negatively amount undergrowth, ground vegetation, state decay trees. Especially undergrowth negatively, as they covered some lead false detections. Based study, collection information should focused mature least current operative densities.