The study contains the results of forest monitoring at three levels: the forests condition assessment at the time of
recording or mapping for this indicator, the seasonal changes assessment in the forests condition, mainly during the
vegetation period and the evaluation of long-term changes in the values of the studied parameters on the example of the
forests recovery after a fire. The use of two indices - NDVI and Image Difference in the boreal forests monitoring is
treated. NDVI assesses the state of plant biomass and its productivity. The rate of Image Difference characterizes the
optical density and allows estimate the density of the forest stand.
In addition, by identifying Image Difference on summer and autumn pictures it can makes a distinction of different wood
species, to divide forest areas, which consist of deciduous and coniferous species and larch which shedded needles at the
end of the vegetation period. Therefore, it is possible to differentiate the pine, cedar, spruce forests on the one side and
birch, larch, alder on the other side. The optical density of the forest decreases after the needles- and the leaf sheddings.
Using the index Image Difference in estimates of long-term changes of the forest stand shows the trend of changes of the
forest density and the tree species composition. The results of the analysis of the recovery process of the forest after a
fire in the period from 1995 to 2009 showed how shoots of birch, larch and pine recover wastelands.