A spectral library of branches for seven boreal and temperate tree species.

Branches have a distinct effect on forest canopy reflectance spectra. Spectral data on branches are therefore essential for interpretation of optical remote sensing data with radiative transfer modeling and machine learning-based approaches. This article presents laboratory-measured reflectance spectra of branches from seven boreal and temperate tree species. A total of 84 branch samples from 21 individual trees representing coniferous and broadleaf tree species were collected in southern Finland between September and November 2024. Spectral measurements were conducted under laboratory conditions using an ASD FieldSpec 4 Standard-Res spectroradiometer (351-2500 nm), combined with either a contact probe setup or an integrating sphere setup, and a halogen light source. These data support more accurate interpretations of multi- and hyperspectral remote sensing data.