Pollen analysis and radiocarbon dating of lake sediment cores from four localities in the Frederikshab district, South-West Greenland, provide a chronology of vegetation changes in the area since c. 10000 B.P. An initial pioneer phase with the early development of some heath communities is followed by a mid postglacial phase in which there is the successive appearance of woody scrub species. A final phase shows the decline of some of these. This is interpreted as a general response to a broad amplitude fluctuation in climate, with its optimal period lying between c. 7600 and 3200 B.P. The detailed composition of the vegetation however is influenced by immigration phenomena, with the appearance of many species lagging behind the attainment of their climatic thresholds. Detailed consideration is given to the possibility of Alnus crispa being present as a scrub component during the climatic optimum.