This dataset contains reflectance and transmittance spectra of leaf and needle samples collected from trees grown in four sites in the Helsinki area in Southern Finland: Otaniemi campus (60°11´N, 24°49´E), Viikki arboretum (60°13´N, 25°00´E), Kumpula botanical garden (60°12´N, 24°57´E), and Ruotsinkylä research forest (60°22´N, 24°59´E).
The spectra have been reported in Hovi, A., Raitio, P., Rautiainen, M., (2017). A spectral analysis of 25 boreal tree species. Silva Fennica, 51(4), 7753, https://doi.org/10.14214/sf.7753. If using the data, please cite the above publication and the Mendeley Dataset: Hovi, A., Rautiainen, M., (2022). Leaf and needle spectra for 25 boreal tree species. Mendeley Data, V1, https://doi.org/10.17632/nvgjcn5nsx.1.
Reflectance and transmittance spectra were measured for a total of 25 tree species close to peak growing season in 2016. In addition to one-time measurements of the 25 species, the dataset contains time series of spectra for the dominating tree species in Finland (Betula pendula, Picea abies, Pinus sylvestris, Populus tremula) from May to October. The number of sampled trees varied from 1 to 3 per species. For each tree, three leaf or needle samples from top part of the tree crown (predominantly sun-exposed foliage) and three samples from bottom part of the tree crown (predominantly shaded foliage) were measured. Both sides of the sample (A = adaxial = upper, B = abaxial = lower) were measured with the following exceptions. Needles of spruce species (Picea abies, Picea glauca, Picea mariana) do not have clearly defined sides, and therefore only one side of the sample (marked as A in the data) was measured. For tamarack (Larix laricina), both sides were measured, but it was not possible to reliably distinguish which is upper and which is lower.
The following additional data were not reported in Hovi et al. (2017), but are included in the dataset for the sake of thoroughness:
i) The measurements of Picea abies and Pinus sylvestris made between 22nd Jul and 1st Aug 2016 employed slightly different needle carriers than the other measurements. This could have affected the comparability of these samples with the others, and these samples should be used with caution.
ii) For Picea glauca, one tree (species labeled as PICGLAA in the data) was sampled that represents a long-needled form of P. glauca (P. glauca var. albertiana (S. Br.) Sarg.).
For further details of the data collection, measurements, and the content of the data files, see Hovi et al. (2017) and README.pdf.