A dataset of multiangular spectra of tree bark for three boreal tree species
The collection and preprocessing of this dataset has been reported in detail in Juola J., Hovi A., Rautiainen M. (2020). Multiangular spectra of tree bark for common boreal tree species in Europe. Silva Fennica vol. 54 no. 4 article id 10331. https://doi.org/10.14214/sf.10331. The dataset includes average multiangular stem bark reflectance spectra of three common boreal tree species found in Europe: silver birch (Betula pendula Roth), Scots pine (Pinus sylvestris L.), and Norway spruce (Picea abies (L.) H. Karst.). Bidirectional reflectance factors (BRF) at visible and near-infrared wavelengths (418-924 nm) are reported for each tree species. Multiangular measurements were performed in six different view angles along the principal plane (29, 58, 65, 90, 115, and 140 degrees), using a laboratory goniometer. The 90° view angle is perpendicular to the sample surface, < 90° view angles are backward-scattering directions, and > 90° view angle are forward-scattering directions. The goniometer utilized a Specim IQ hyperspectral imaging spectrometer. The nominal illumination angle for the measurements was 40°. The average reflectance spectrum for each tree at each view angle was calculated by averaging over all measured samples. The samples comprised of stem bark taken at different heights along the tree stem, from two individual trees per species. The samples were collected from forest stands located in Keimolanmäki, Vantaa, Finland (60°19´N, 24°50´E), in March-April of 2019, and the measurements were conducted within 12 days from the sample collection. The study stands were typical managed and even-aged forests in Finland, approximately 40 years old, and grew on a mesic site type on mineral soil. The spreadsheet "multiangular_spectra_juola_et_al_2020.csv" in this dataset is organized as follows: first column "tree_species" (pinus_sylvestris, picea_abies, betula_pendula) indicates the tree species, second column "view_angle" (29, 58, 65, 90, 115, 140) indicates the view angle, and the subsequent columns "wl417.5"- indicate the measured BRF value at that wavelength. A separate list of the wavelengths (without the prefix "wl") is provided in the file "list_of_wavelengths_juola_et_al_2020.csv". The encoding of the csv files is UTF-8.
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See Juola J., Hovi A., Rautiainen M. (2020). Multiangular spectra of tree bark for common boreal tree species in Europe. Silva Fennica vol. 54 no. 4 article id 10331. https://doi.org/10.14214/sf.10331.