POSSIBILITIES OF CHANGE DETECTION OF TREE AND FOREST ATTRIBUTES BY COMBINING TERRESTRIAL LASER SCANNING BASED 3D POINT CLOUDS WITH UAV DATA

Exact and up-to-date information about forest resources is needed for decision makers when planning the use of forests. Knowledge about changes in forest environment and tree growth is a key factor for example when predicting the effects of climate change and estimating the amount of biomass and sequestered carbon in forests. New technologies, such as unmanned aerial vehicles (UAVs), allow one to collect detailed information of forests from above with relatively close range. UAVs have already been used e.g. for environmental monitoring, tree attribute detection and forest inventories. However, also accurate and in detail reference measurements are needed for estimating forest resource information, to be able to take advantage of the new methods. Terrestrial laser scanning (TLS) can be used for measuring tree and forest attributes from ground in very high detail. This study shows how follow-up measurements with TLS-based three-dimensional point clouds allow one to investigate the changes both on individual tree and plot level. Based on the results, the possibilities of using TLS data as reference for UAV inventories or together with UAV based measurements are discussed in an attempt to find more accurate and effective solutions for forest change detection.