| Summary: | Absolute and relative pollen diagrams from three radiocarbon‑dated lake sediment cores were used to illustrate the Flandrian vegetation history of an area between Lake Inari and Varangerfjorden in northernmost Fennoscandia. The area is traversed by the modern pine forest limit and by the Main sub‑stage (Younger Dryas) end‑moraines. After an early Flandrian birch phase, pine immigrated around 8500 B.P., spreading already at that time into areas beyond its present range. Pine invasion was completed by 7500 B.P. The retreat of pine started around 5000 B.P. and continued until 3000‑2500 B.P., after which little further change is evident. The pine invasion is considered mainly a migration event, while the retreat was probably climatically determined. The Younger Dryas – early Flandrian transition is defined by the pollen sequence Artemisia zone ‑ birch zone, the zone boundary being correlative with the ice retreat from the Main sub‑stage moraines. This pollen sequence is similar to the one described from the Salpausselkä moraines in southeast Finland and has a similar relationship to the ice retreat history.
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