Studies of macrofossils indicate that the vegetation near Regstrup in north-west Sjælland, Denmark, from c. 13 600 to 13 500 cal. years BP was dominated by dwarf-shrub heaths. Betula pubescens (downy birch) arrived at c. 13 500 cal. years BP and became common after c. 13 200 cal. years BP. Open forests with B. pubescens and Populus tremula (aspen) dominated until c. 12 500 cal. years BP, indicating that an Allerød-type environment persisted for c. 350 years after the cooling at the onset of the Younger Dryas, which is dated to c. 12 850 years BP in ice cores from Green-land. Betula nana was common after c. 12 500 cal. years BP, indicating a return to a tundra-like landscape with dwarf-shrub heaths. The fauna included Rangifer taran-dus (reindeer), Castor fiber (Eurasian beaver) and possibly Lemmus lemmus (Norway lemming). The lake deposits contain remains of many species of aquatic plants and animals, including three species of fish. The flora and fauna indicate that the lake water was fairly nutrient-rich and alkaline.