Multi-temporal high-resolution data products of ecosystem structure derived from country-wide airborne laser scanning surveys of the Netherlands

This data repository contains a set of multi-temporal data products of ecosystem structure derived from four national ALS surveys of the Netherlands (AHN1–AHN4) (folder: 1. Data_products). Four sets of 25 LiDAR-derived vegetation metrics representing ecosystem height, cover, and structural variability are provided at 10 m spatial resolution, providing valuable data sources for a wide range of ecological research and field beyond. All 25 LiDAR metrics were calculated using Laserfarm workflow (https://laserfarm.readthedocs.io/en/latest/) (building on the user-extendable features from the “Laserchicken” software: https://laserchicken.readthedocs.io/en/latest/#features). All metrics are calculated with the normalized point cloud. More details on metric calculation are provided on GitHub (Laserchicken: https://github.com/eEcoLiDAR/laserchicken and Laserfarm: https://github.com/eEcoLiDAR/Laserfarm), as well as on the “Laserchicken” documentation page (https://laserchicken.readthedocs.io/en/latest/). We also provided masks to minimize the influence of water surfaces, buildings and roads, as well as powerlines in the data products (folder: 2. Masks). Since the point density of each AHN dataset has changed significantly which may have influence on generated LiDAR metrics, we also provided the four raster layers of point density (all points) for each AHN dataset (folder: 3. Point_density). Two use cases demonstrated the utility of the presented data products: (use case 1) monitoring forest structural change across time using multi-temporal ALS data and (use case 2) comparison of vegetation structural difference within Natura 2000 sites. The used data are also provided (folder: 4. Use_case). Note that all the raster layers and shapefiles provided in this repository are under the local Dutch coordinate system “RD_new” (EPSG: 28992, NAP:5709). Three subfolders are included: 1. Data_products · AHN1.zip · AHN2.zip · AHN3.zip · AHN4.zip · Maps It contains four folders with 25 LiDAR metrics at 10 m resolution generated from each AHN dataset. The file names and their corresponding LiDAR metrics can be found in Table 1. An additional folder (Maps) contains the maps (.pdf format) of all 25 metrics for each AHN dataset. 2. Masks · ahn3_10m_mask_building_road_water.tif · ahn4_10m_mask_building_road_water.tif · ahn4_10m_mask_powerline.tif It contains two mask layers of water surfaces, buildings and roads for both AHN3 and AHN4 data products based on the Dutch cadaster data (TOP10NL) from 2018 (corresponding to AHN3) and 2021 (corresponding to AHN4) (https://www.kadaster.nl/zakelijk/producten/geo-informatie/topnl). In the masks, water surfaces, buildings and roads were merged into one class with pixel value assigned to 1 and the rest has the pixel value of 0. There is also a powerline mask generated from the AHN4 dataset at 10 m resolution, where pixels containing powerlines were assigned a value of 1 and the rest as NoData. We provide those masks to minimize the inaccuracies of the data products caused by human infrastructures and water surfaces. 3. Point_density · ahn1_10m_point_density.tif · ahn2_10m_point_density.tif · ahn3_10m_point_density.tif · ahn4_10m_point_density.tif It contains four raster layers (at 10 m resolution) representing the point density of each AHN dataset. 4. Use_case 1. Multi-temporal_AHN · Data · Usecase_multi-temporal_AHN.R It contains the input data for the use case data processing (i.e. Data folder), including the shapefile of the area (i.e. shp folder), and extracted pixel value from six selected LiDAR metrics from AHN1–AHN5 (i.e. Metrics folder), and the selected LiDAR metrics of the area (e.g. Hp95 folder), and the R code for data processing (i.e. Usecase_multi-temporal_AHN.R). 2. Natura2000 · Data · Natura2000_end2021_HABITATCLASS.csv · Natura2000_NL_habitat_grouped.csv · Usecase_Natura2000.R It contains a folder of the input data used for the use case (i.e. Data folder), including the shapefile (i.e. shp folder) of the Natura 2000 sites in the Netherlands (i.e. Nature2000_NL_RDnew.shp) and the 100 random sample plots from each habitat type (e.g. woodland_points.shp), and the LiDAR metrics from AHN4 used for demonstrating the vegetation structure within each habitat type (i.e. AHN4_metrics folder). The table “Natura2000_end2021_HABITATCLASS.csv” is the original attribute table of Natura 2000 sites, including information related to the description of habitat classes (column “DESCRIPTION”), the code corresponding to the habitat class (column “HABITATCODE”), the code for the specific site (column “SITECODE”), and the percentage of the cover of a specific habitat class in one site (column “PERCENTAGECOVER”). The table “Natura2000_NL_habitat_grouped.csv” contains two subtabs, one (i.e. “Habitatclass”) is the copy of the original attribute table of Natura 2000 sites in the Netherlands, and the other one (i.e. “Habitat_class_summary”) is the grouped habitat type based on the dominant habitat class (i.e. class with the highest percentage cover) in each site. Different colors indicate different habitat types, corresponding to the colors in the first tab (“Habitatclass”) where the dominant habitat class was highlighted for each site. Code availability Jupyter Notebooks for processing AHN datasets: https://github.com/ShiYifang/AHN Laserfarm workflow repository: https://github.com/eEcoLiDAR/Laserfarm Laserchicken software repository: https://github.com/eEcoLiDAR/laserchicken Code for downloading AHN dataset: https://github.com/ShiYifang/AHN/tree/main/AHN_downloading Code for generating masks for AHN datasets: https://github.com/ShiYifang/AHN/tree/main/AHN_masks Code for demonstration of ecological use cases: https://github.com/ShiYifang/AHN/tree/main/Use_case本数据集仓库包含一套基于荷兰四次全国机载激光扫描（Airborne Laser Scanning, ALS）调查（AHN1至AHN4）生成的生态系统结构多时序数据产品（存储于文件夹：1. Data_products）。本数据集提供四组共25项由激光雷达（LiDAR）衍生的植被特征参数，以10米空间分辨率表征生态系统的高度、覆盖度与结构变异性，可为各类生态学及跨领域研究提供宝贵的数据支撑。所有25项激光雷达特征参数均通过Laserfarm工作流（https://laserfarm.readthedocs.io/en/latest/）计算得到（该工作流基于"Laserchicken"软件的用户可扩展功能开发：https://laserchicken.readthedocs.io/en/latest/#features），且所有参数均基于归一化点云计算完成。关于特征参数计算的更多细节，可参见GitHub仓库（Laserchicken：https://github.com/eEcoLiDAR/laserchicken 与Laserfarm：https://github.com/eEcoLiDAR/Laserfarm）及"Laserchicken"官方文档页面（https://laserchicken.readthedocs.io/en/latest/）。我们还提供了掩膜图层，以尽可能降低水面、建筑、道路以及电力线路对数据产品的影响（存储于文件夹：2. Masks）。鉴于各AHN数据集的点云密度存在显著差异，可能对生成的激光雷达特征参数产生影响，我们同时提供了对应各AHN数据集的全点云点密度栅格图层（存储于文件夹：3. Point_density）。本数据集提供两个应用案例以展示数据产品的实用性：（案例1）利用多时序机载激光扫描数据监测森林结构动态变化；（案例2）对比Natura 2000保护地内的植被结构差异。相关应用所用数据已一并提供（存储于文件夹：4. Use_case）。请注意，本仓库内的所有栅格图层与矢量文件均采用荷兰本地坐标系"RD_new"（EPSG: 28992，NAP:5709）。 1. Data_products · AHN1.zip · AHN2.zip · AHN3.zip · AHN4.zip · Maps 该子文件夹包含四个子目录，分别存储由各AHN数据集生成的25项10米分辨率激光雷达特征参数。文件名与对应激光雷达特征参数的对应关系详见表1。额外的Maps文件夹包含各AHN数据集全部25项特征参数的PDF格式可视化图谱。 2. Masks · ahn3_10m_mask_building_road_water.tif · ahn4_10m_mask_building_road_water.tif · ahn4_10m_mask_powerline.tif 该子文件夹包含两组基于荷兰地籍数据（TOP10NL）生成的掩膜图层，分别对应2018年（匹配AHN3数据集）与2021年（匹配AHN4数据集）的水面、建筑与道路掩膜（https://www.kadaster.nl/zakelijk/producten/geo-informatie/topnl）。在掩膜图层中，水面、建筑与道路被合并为一类，像素值设为1，其余区域像素值为0。此外还包含一份基于AHN4数据集生成的10米分辨率电力线路掩膜，含电力线路的像素值设为1，其余区域为无数据（NoData）。我们提供上述掩膜以尽可能减少人工设施与水面对数据产品精度造成的误差。 3. Point_density · ahn1_10m_point_density.tif · ahn2_10m_point_density.tif · ahn3_10m_point_density.tif · ahn4_10m_point_density.tif 该子文件夹包含四个10米分辨率的栅格图层，分别表征各AHN数据集的点云密度。 4. Use_case 1. Multi-temporal_AHN · Data · Usecase_multi-temporal_AHN.R 该子文件夹包含案例1的数据处理所需输入数据（即Data文件夹），其中包含研究区域的矢量shapefile（即shp文件夹）、从AHN1至AHN5中提取的6项选定激光雷达特征参数的像素值（即Metrics文件夹）、对应研究区域的选定激光雷达特征参数数据（如Hp95文件夹），以及数据处理所用的R脚本（即Usecase_multi-temporal_AHN.R）。 2. Natura2000 · Data · Natura2000_end2021_HABITATCLASS.csv · Natura2000_NL_habitat_grouped.csv · Usecase_Natura2000.R 该子文件夹包含案例2所用的输入数据文件夹（即Data文件夹），其中包含荷兰Natura 2000保护地的矢量shapefile（即shp文件夹，对应文件为Nature2000_NL_RDnew.shp）、每种生境类型对应的100个随机采样样点（如woodland_points.shp），以及用于展示各生境类型内植被结构的AHN4激光雷达特征参数数据（即AHN4_metrics文件夹）。 表格"Natura2000_end2021_HABITATCLASS.csv"为Natura 2000保护地的原始属性表，包含与生境类型描述相关的信息（列"DESCRIPTION"）、对应生境类型的编码（列"HABITATCODE"）、具体保护地的编码（列"SITECODE"），以及某保护地内特定生境类型的覆盖百分比（列"PERCENTAGECOVER"）。 表格"Natura2000_NL_habitat_grouped.csv"包含两个子表：其一（"Habitatclass"）为荷兰Natura 2000保护地原始属性表的副本；其二（"Habitat_class_summary"）为基于各保护地内占比最高的优势生境类型进行分组后的生境类型汇总表。不同颜色代表不同生境类型，与第一个子表（"Habitatclass"）中的配色一致，其中各保护地的优势生境类型已被高亮标注。 代码获取 用于处理AHN数据集的Jupyter Notebook： https://github.com/ShiYifang/AHN Laserfarm工作流仓库： https://github.com/eEcoLiDAR/Laserfarm Laserchicken软件仓库： https://github.com/eEcoLiDAR/laserchicken AHN数据集下载代码：https://github.com/ShiYifang/AHN/tree/main/AHN_downloading AHN数据集掩膜生成代码：https://github.com/ShiYifang/AHN/tree/main/AHN_masks 生态学应用案例演示代码：https://github.com/ShiYifang/AHN/tree/main/Use_case