Point clouds with ground point classification and individual tree segmentation of 28 northern boreal forest and tundra sites from UAV-based lidar surveys in western and central parts of Alaska in 2024@en

This data set presents LiDAR 3D point clouds with centimetre precision, colored by a RGB camera module. 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 Boreal Forest and the Tundra-Taiga Ecotone (TTE). The aim is to map the forest structure and in particular to segment individual trees. This allows structural and biophysical information to be derived on forest condition, stand 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 University of Alaska Fairbanks (UAF). It took place in the summer of 2024, from 18 June to 17 July. The study area covers boreal forests in different bio-climatic regions and revisits sites established in 2023 and adds more sites. Additionally, the Tundra-Taiga Ecotone was sampled at the Seward Peninsula from the westernmost forests in Alaska close to the settlement of Council and towards Nome. 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, one or, in rare cases, multiple 30-metre-diameter plots were inventoried as ground reference data. The recordings were made at an altitude of 70 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. The raw data processing steps involved correcting the flight trajectories in POSPAC PPTX, flight strip alignment in software YellowScan CloudStation, and colorization with RGB module picture data. The subsequent processing and metadata collection in PC2RCHIVE includes (i) ground classification, (ii) creating Digital Terrain Model (DTM), Digital Surface Model (DSM) and Canopy Height Model (CHM), (ii) tree segmentation, (iv) generating maps, and (v) user provided metadata and relevant information from the data processing are summarized in tables.本数据集提供了厘米级精度的激光雷达（LiDAR）三维点云，并通过RGB相机模块赋予点云色彩信息。本数据集收录了经过处理的点云数据，采集设备为搭载无人机（Unmanned Aerial Vehicle, UAV）平台的激光扫描仪YellowScan Mapper。采集区域涵盖北方森林与苔原-泰加林交错带（Tundra-Taiga Ecotone, TTE）的部分范围。本数据集的核心目标为绘制森林结构图谱，尤其聚焦于单木分割任务，借此可提取森林健康状况、林分结构、地形地貌、植被形态、干扰事件（野火、融滑塌、风灾）、热喀斯特湖岸界面等相关的结构与生物物理信息。本次野外作业由阿尔弗雷德·魏格纳研究所、亥姆霍兹极地与海洋研究中心（AWI）以及阿拉斯加大学费尔班克斯分校（UAF）的研究人员规划并实施，作业时间为2024年夏季，即6月18日至7月17日。研究区域覆盖不同生物气候区的北方森林，既对2023年设立的样地进行了重访，又新增了多个采样点。此外，研究团队在苏华德半岛对苔原-泰加林交错带开展采样，采样范围覆盖阿拉斯加最西部的森林（临近Council定居点）直至诺姆方向。针对大量采样点，研究团队基于卫星数据预先选定采样位置。在每个采样点，研究团队以间隔20米的平行飞行航线构建网格，飞行覆盖宽度不小于50米、长度不小于500米的样带区域。地面层面，每个采样点设置1个（极少数情况为多个）直径30米的样地，开展野外调查以获取地面参考数据。按照设备制造商的建议，飞行采集时的离地高度为70米，飞行速度为5米/秒。每次飞行作业前，均搭建GPS基准站以采集数据，用于后续的地理校正。原始数据处理流程包括：在POSPAC PPTX中校正飞行轨迹，在YellowScan CloudStation软件中完成航带拼接，并通过RGB相机模块的影像数据对点云进行色彩赋值。后续在PC2RCHIVE中开展的处理与元数据收集工作包括：(1) 地面点分类；(2) 生成数字地形模型（Digital Terrain Model, DTM）、数字表面模型（Digital Surface Model, DSM）以及冠层高度模型（Canopy Height Model, CHM）；(3) 单木分割；(4) 生成专题地图；(5) 将用户提供的元数据与数据处理过程中产生的相关信息汇总为表格。