Detecting shrub encroachment in semi-natural grasslands using UAS LiDAR

Shrub encroachment in semi-natural grasslands threatens local biodiversity unless management is applied to reduce shrub density. Dense vegetation of Cytisus scoparius homogenizes the landscape negatively affecting local plant diversity. Detecting structural change (e.g., biomass) is essential for assessing negative impacts of encroachment. Hence, exploring new monitoring tools to achieve this task is important for effectively capturing change and evaluating management activities. This study combines traditional field-based measurements with novel Light Detection and Ranging (LiDAR) observations from an Unmanned Aircraft System (UAS). We investigate the accuracy of mapping C. scoparius in three dimensions (3D) and of structural change metrics (i.e. biomass) derived from ultra-high density point-cloud data (>1000 pts/m2). We utilized a 3D point-based classification to distinguish shrub genera based on their structural appearance (i.e. density, light penetration and surface roughness) ...