The spatial and temporal patterns of the forest background reflectance are critically important for retrieving the biophysical parameters of the forest canopy (overstory) and for ecosystem modeling. In this short com-munication paper, we retrieve the reflectance and seasonal changes of the forest background at 500 m reso-lution with the 8-day MODIS bidirectional reflectance distribution function (BRDF) model parameters product. For the first time, the satellite data derived results are directly validated with in situ measured sea-sonal reflectance trajectories of boreal forest understory layers. Our results illustrate the importance of taking into account the documented quality and limitations of the MODIS BRDF product.