This data set presents LiDAR 3D point clouds with centimetre precision. It is a collection of processed point clouds that were collected by a UAV-based laser scanner (YellowScan Mapper). The region covered is part of the Northern Boreal Forest and the Tundra-Taiga Ecotone (TTE). The aim is to map the forest structure, and in particular to segment individual trees. Additionally, mapping arctic lakes and conduct ecological studies (beavers). This allows structural and biophysical information to be derived on forest condition, structure, topography, morphology, disturbance (wildfire, thaw slumps, wind events), thermokarst lakeshore interfaces, etc. The fieldwork was planned and carried out by researchers from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (AWI) and the North-Eastern Federal University of Yakutsk (NEFU). It took place in the late summer of 2021, from 17 July to 29 August. The principal study areas are the intramontane Oymyakon region in the Verkhoyansk mountain range near Lake Ulu, and the central-eastern Yakutian lowlands eas of the Lena river close to Yakutsk, with a slightly different ecological setting. At a multitude of sites, we pre-selected locations based on satellite data. At each site, transects at least 50 m wide and 500 m long were flown in a grid of parallel flight lines 20 m apart. At the ground level, mostly one or, in rare cases, multiple 30-metre-diameter plots were inventoried as ground reference data. The recordings were made at an altitude of 60-100 m above ground liftoff at a speed of 5 m/s, as recommended by the manufacturer. Before each flight, a GPS base station was set up to collect data for later geographic correction.

Cloth-Simulation-Filter parameters: Classification threshold (m) is the maximum distance between the cloth and a point to be classified as ground (Values used: 0.1/0.2/0.3). Cloth resolution (m) sets the cloth's cell size and is set to a value that ensures flexibility for following the micro-topography, while not being smaller than the inner diameter of the high, hollow vegetation bodies (Values used: 0.1/0.2). Rigidness is the first order stiffness of the cloth (Values used: 1 - flat scenes, 2 - minor relief, 3 - steep slopes).Data comment on point clouds/.las-file: The point clouds are provided in data format LAS (v1.2 format 3). It contains the RGB information if available. Further, the scalar fields are: (1) intensity, (2) return number of the points, (3) number of returns for the point, (4) classification, either 0 which is aboveground or 2 wich is ground, (5) scan angle rank, (7) point source ID, which is the flight strip, (8) GPS time, and, (9) treeID for the "..._treesonly"-files, which contains unique integer IDs for each segmented tree.This data was collected during the international joint Russian-German expedition 'RU-Land_2021_Yakutia' in collaboration between the Alfred-Wegener-Institute, Helmholtz Centre for Polar and Marine Research in Potsdam, and the North-Eastern Federal University of Yakutsk, with UAV flight support by the Technical University Berlin. Additional funding for equipment was provided by the Potsdamer InnoLab für Arktisforschung grant no. F221-08-AWI/001/002, namely the Brandenburg Ministry for Science, Research and Culture. This project has been supported by the DataHub Information Infrastructure funds, projects BorFIT and PC2RCHIVE.