Hyperspectral datasets of boreal forest understory vegetation in Finland

The understory layer or `forest floor´ typically has a significant role in forming the spectral signal of a sparse boreal forest. However, the lack of field measurements on understory spectra and their seasonality has restricted the development of remote sensing algorithms for phenological monitoring. This paper reviews recent efforts to establish hyperspectral databanks of forest understory vegetation in Finland, also unique to the entire boreal zone. Both multiangular and multitemporal data sets comprising the most common understory species have been collected. The data can be applied, for example, to separate the contributions of the tree layer and understory to the spectral signal of a forest through radiative transfer modeling.