EN
Thermal conditions of early spring (March-April) were the main factor that determined the sizes of wood increments of spruces in the subalpine forest zone of the Beskid Żywiecki Mountains. Tree-ring widths of trees growing above the altitude of 800 meters were also influenced by the temperatures of June-August. Diverse sensitivity of the spruces to summer thermal conditions allowed us to separate two dendroclimatologically different zones in the subalpine forest zone: an upper one, above the 800 meters izohypse, and a lower one, below this altitude.