Fig. 1. Photographs of a natural stage lingonberry shrub with berries (left), after removing the berries (centre), and forest floor after removing the shrubs (right). The measurements were made from circular field of view between the yellow markings edited in the photos.

Fig. 2. Illustration of the implemented laboratory setup for measuring BRF. Adopted from Suomalainen et al. (2009).

Fig. 3. Applied spectral analyses and sample types.

Fig. 4. Seasonal dynamics of nadir view spectra for lingonberry (red) and blueberry (blue) in 2017. The spectral bands correspond to the Sentinel-2 MSI sensor. Error bars are standard deviations. Different phenological stages are indicated by diamonds (with flowers), circles (with berries), and squares (no flowers or berries). Illumination at view zenith angle +40°.

Fig. 5. Effect of berries and flowers on nadir BRF spectra. Shaded areas are standard deviations. Illumination at view zenith angle +40°.

Fig. 6. Mean spectral signatures of contributing scattering components.

Fig. 7. Seasonal dynamics of vegetation indices and red-edge inflection point in 2017 for lingonberry (red) and blueberry (blue). Different phenological stages are indicated by diamonds (with flowers), circles (with berries), and squares (no flowers or berries). Illumination at view zenith angle +40°.

Fig. 8. Multiangular spectra of lingonberry (left and centre panels) and blueberry (right most panels) in six spectral bands corresponding to Sentinel-2 MSI sensor. View angle dependence within –35° and +35° zenith angles of BRF is shown for samples with flowers or berries (first row panels), for samples without flowers or berries (second row panels), and for the corresponding ratios (third row panels). Illumination at view zenith angle +40°.