Reflectance, transmittance and absorptance of a leaf of Betula pubescens (downy birch) at 1 nanometre intervals from 350 to 2500 nanometres. The data were collected under the auspices of the Russian-British project “Multiplatform remote sensing of the impact of climate change on northern forests of Russia” funded by the British Council (Institutional Links Programme Grant no. 352397111) and the Ministry of Science and Higher Education of the Russian Federation (project RFMEFI61618X0099). The FieldSpec Pro Hi-Res spectroradiometer was purchased under the Development Programme of M. V. Lomonosov Moscow State University. The SLAP project to create a spectral library was supported in 2014-2017 by the EU 'Interact' programme to support the research and education network of Arctic research stations (www.eu-interact.org).