A dataset of stem bark reflectance spectra for boreal and temperate tree species

The collection and preprocessing of this dataset has been reported in detail in Juola J., Hovi A., Rautiainen M., 2022. A spectral analysis of stem bark for boreal and temperate tree species. Ecology and Evolution. DOI:10.1002/ece3.8718

The dataset includes stem bark reflectance spectra of ten boreal and temperate tree species. We measured hemispherical-directional reflectance factors (HDRF) of stem bark samples. The data were measured using a Specim IQ imaging spectrometer attached to a tree mounting setup. The imaging spectrometer operates in the visible and near-infrared wavelength region (400–1000 nm). The measurements were made in the Greater Helsinki area in Finland, and in Järvselja in Estonia. We measured 20 trees per species, accounting to a total of 200 unique stem bark samples. One sample refers to a hyperspectral reflectance image taken of a single tree stem. The 200 mean spectral signatures (presented in this dataset) were calculated for each sample by averaging the HDRF values over all pixels per wavelength. The measurements were conducted from May to August 2020. All measurements were made under natural illumination conditions and the images were taken in perpendicular view-angle to the tree stem. The dataset includes two tabular files that contain: 1) the mean reflectance spectrum for each of the ten common boreal and temperate tree species (calculated from the 20 samples per species), and 2) all 200 reflectance spectra (20 per tree species). The sampled species were: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst), silver birch (Betula pendula Roth), grey alder (Alnus incana (L.) Moench), black alder (Alnus glutinosa (L.) Gaertn.), English oak (Quercus robur L.), European aspen (Populus tremula L.), European ash (Fraxinus excelsior L.), Norway maple (Acer platanoides L.), and littleleaf linden (Tilia cordata Mill.).

The two spreadsheets are organized as follows: first three rows that start with hashtag (#) contain comments for citing, first column "tree_species" (Pinus_sylvestris, Picea_abies, Betula_pendula...) indicates the tree species, and the subsequent columns "wl397.32"-"wl1003.58" indicate the measured HDRF value at that wavelength. The encoding of the csv file is UTF-8.

The data in file "mean_tree_species_stem_bark_reflectance_spectra_Juola_et_al_2021.csv" is the same as what can be found in Version 1. We only changed the first row's naming to make it clearer.

If you use this dataset, please cite Juola et al. [1,2]:
[1] Juola J., Hovi A., Rautiainen M., 2022. A spectral analysis of stem bark for boreal and temperate tree species. Ecology and Evolution. DOI:10.1002/ece3.8718
[2] Juola J., Hovi A., Rautiainen M., 2022. A dataset of stem bark reflectance spectra for boreal and temperate tree species. Mendeley Data, V2, doi: 10.17632/pwfxgzz5fj.2

本数据集的收集与预处理已由Juola J.、Hovi A.、Rautiainen M.于2022年在《生态学与进化》杂志中详细报道。该数据集包含十种寒带和温带树种的主干树皮反射光谱。研究者测量了主干树皮样本的半球定向反射率因子（HDRF）。数据测量采用附着于树木固定装置的Specim IQ成像光谱仪进行，该光谱仪在可见光和近红外波长区域（400–1000 nm）内运行。测量工作在芬兰的赫尔辛基大区以及爱沙尼亚的Järvselja进行。每个树种测量20棵树，总计200个独特的树皮样本。一个样本指代一张单棵树干的高光谱反射图像。本数据集中呈现的200个平均光谱特征（每个样本通过平均所有像素在该波长的HDRF值计算得出）均由这些样本计算得出。测量工作于2020年5月至8月期间进行。所有测量均在自然光照条件下进行，图像以垂直于树干的角度拍摄。数据集包含两个表格文件，其中包含：1）十个常见寒带和温带树种的平均反射光谱（每个树种20个样本计算得出），以及2）所有200个反射光谱（每个树种20个）。样本树种包括：苏格兰松（Pinus sylvestris L.）、挪威云杉（Picea abies (L.) Karst）、银桦（Betula pendula Roth）、灰桦（Alnus incana (L.) Moench）、黑桦（Alnus glutinosa (L.) Gaertn.）、英国栎（Quercus robur L.）、欧洲白桦（Populus tremula L.）、欧洲白蜡（Fraxinus excelsior L.）、挪威枫（Acer platanoides L.）和欧洲梣（Tilia cordata Mill.）。两个电子表格的编排如下：前三行以井号(#)开始的行包含引用注释，第一列“tree_species”（Pinus_sylvestris、Picea_abies、Betula_pendula...）指示树种，后续列“wl397.32”至“wl1003.58”表示在该波长的HDRF测量值。csv文件的编码为UTF-8。

文件“mean_tree_species_stem_bark_reflectance_spectra_Juola_et_al_2021.csv”中的数据与版本1中的数据相同，我们仅更改了第一行的命名以使其更清晰。

若使用本数据集，请引用Juola等[1,2]的研究成果：
[1] Juola J.、Hovi A.、Rautiainen M.，2022.寒带和温带树种主干树皮的频谱分析. 生态学与进化. DOI:10.1002/ece3.8718
[2] Juola J.、Hovi A.、Rautiainen M.，2022.寒带和温带树种主干树皮反射光谱数据集. Mendeley Data，V2，doi: 10.17632/pwfxgzz5fj.2