THE OCCURRENCE OF THERMOPHILOUS TREES IN THE SCANDES MOUNTAINS DURINGTHE EARLY HOLOCENE - EVIDENCE FOR A DIVERSE TREE FLORA FROM MACROSCOPIC REMAINS

1 Macroscopic remains of the fairly thermophilous tree species Alnus g lutinosa, Tilia cordata and Betula pendula were recovered in subalpine and adjacent boreal environments far above and beyond their present-d ay distributional limits. This establishes that the early Holocene tre e flora of the Scandes Mountains in northern Sweden was indeed richer than it is today. 2 Dates ranged between c. 8600 and 7000 radiocarbon years sp. These are much earlier than previous estimates by convention al pollen stratigraphical analyses of the arrival of these species at their maximum geographical limits. This highlights problems in using o nly pollen data for vegetation reconstruction, and suggests re-evaluat ion of earlier records. 3 The results, together with similar macrofoss ils for Picea abies and Larix sibirica in northern Sweden, suggest tha t many tree species spread rapidly and became established at their mos t extended range limits during the early Holocene. Abundances have sub sequently varied in accordance with the ecology of individual species as well as with climatic change. 4 Palaeoclimatic inferences may sugge st a strongly continental climate, i.e. warmer and drier summers and p ossibly fairly cold winters between 8600 and 7000 sp relative to the p resent. Some change towards a more oceanic climate regime with less pr onounced seasonal contrasts may have occurred towards the end of the p eriod.