An increasing corpus of knowledge on the history of the Arctic flora is showing that plant life at high latitudes has a long history and that therefore many of the species that inhabit these regions will have endured extensive and prolonged climatic fluctuations over the past 2-3 million years. The chloroplast DNA studies on Saxifraga oppositifolia and other studies suggest that the founding stocks of the arctic flora appeared at the end of the Pliocene (approximately 3 Ma BP) and the genetic imprint of this migration can still be traced around the shores of the Arctic Ocean (Abbott & Brochmann, 2003). The presence of many subspecies and local ecotypes indicates the existence of considerable genetic variability despite the peripheral nature of these high-latitude sites.

The long-term effect of warming in the Arctic may therefore be expected to operate at a genetic level as probably it has done in the past. The polar night will continue to impose a long dormant period in the High Arctic for which the present flora is well adapted. The prospect of the liberation of large areas of land from permanent ice cover should provide a wealth of terrain for the continued existence and probable new flourishing of this remarkable flora. Climatic warming may cause the polar bear to disappear, but this is only a species that has evolved over the past 100 000 years, and cannot compare with plants in long-term occupation of the Arctic. Botanists in the future may look forward confidently to relaxed exploration of a diverse and plentiful flora as far north as land exists without the inconveniences and risks of ursine disturbance.

Fig. 7.1 Machair-forming sand dunes at Luskentyre (Gaelic, Losgaintir), Harris, Outer Hebrides. As these dunes erode the sand is blown landwards and contributes to the renewal and maintenance of species diversity in the coastal machair (machair from Scots Gaelic — a low-lying plain).

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