EN
An influence of environmental changes upon forest tree species competition was studied for suggested scenario of environmental changes (3−4°C increase of monthly temperatures), 8 main tree species and 6 natural regions. For a synthetic assessment of the reaction of various species for thermal and higric parameters of the climate, the growth multipliers DDGF and SMGF were used. The main environmental factor influencing future growth of tree species in Poland will be water shortage due to increased evapotranspiration. Regional decrease of water sensitive species importance, eg. alder, spruce and birch, accompanied by country−scale expansion of highly competitive, late−successional species, eg. beech and hornbeam is expected.