Regions characterized by a growing phase of 6-9 months, sufficient rainfall (in particular during the summer) and cold winters are populated by broadleaved forests as the climax association at most stands.

Most species of these forests in the holarctic region migrated after the last ice ages from southern directions into the area. Therefore, plant life is dominated by few species, e.g. oaks and beeches. Natural exceptions from the population by broadleaved forests in the region marked are located in higher mountains (coniferous forests) and in regions of high humidity (bogs) or dryness (steppe).