Jökull - 01.12.1999, Blaðsíða 16

The pollen data suggest that the importance of Salix
in the surroundings of Lake Torfadalsvatn de-
creased rapidly at 8800 BP, at the same time as Em-
petrum nigrum, Juniperus communis and Betula
nana expanded. Rundgren (1998) proposed that this
abrupt vegetational change may be a response to a
sudden temperature rise in combination with drier
summer conditions. Increased values for several
herb-pollen taxa, for example Ranunculus type,
Thalictrum alpinum, Potentilla type, Plantago
maritima and Galium type, suggest a coincident di-
versification of vegetation. The vegetation on
northernmost Skagi in the period 8800-8000 BP can
be characterized as a dwarf-shrub and shrub tundra.
8000-7800 BP
The information concerning environmental condi-
tions on northernmost Skagi during this episode is re-
stricted to the terrestrial pollen record from Lake
Torfadalsvatn (Rundgren, 1998). Juniperus communis
and Betula nana became even more important in the
vegetation after 8000 BP, and there was a concomitant
decline in Empetrum nigrum. The pollen data indicate
an expansion of Poaceae after 8000 BP, and the most
abundant herb-pollen taxa recorded for the period
8000-7800 BP are Ranunculus type, Thalictrum
alpinum, Apiaceae, Plantago maritima, Galium type
and Sedum type. However, herbs were probably only
of minor importance in the vegetation, which may be
Fig. 10. Palaeogeographical map of northernmost Skagi at 9000 BP with inferred terrestrial vegetation and sea-ice conditions.
T=Torfadalsvatn; H=Hraunsvatn; G=Geitakarlsvötn; K=Kollusátursvatn; N=Neðstavatn; 0=Open section; A, B, C=raised
beach ridge at 65,43-50 and 22-31 m a.s.l. - Kort afnyrsta hluta Skaga eins og hann hefur litið útfyrir 9000 BP. Gróðurfar og
hafísástand er einnig sýnt. T=Torfadalsvatn; H=Hraunsvatn; G=Geitakarlsvötn; K=Kollusátursvatn; N=Neðstavatn;
0=Opnur; A= Fornar strandlínur við 65, 43-50 og 22-31 m y.s.
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JOKULL, No. 47, 1999