Recall from Chapter 2 that the term tundra applies to a wide range of Arctic vegetation, although its basic meaning is treeless. Tundra accounts for about 20% of the land surface within the Arctic Circle. At the southern end of tundra, we encounter the forest-tundra ecotone, some 50-100 km wide, which in turn transitions to boreal forest. The range of climatic conditions in tundra areas is large (Barry etal., 1981; Ohmura, 2000), not only between major tundra types (Chapter 2), but over short distances within a tundra type. The latter issue is highlighted in energy balance studies from the LAII program (Table 5.4). Polar desert is the most extreme of tundra types. Polar desert is particularly fascinating, and warrants more discussion.
Polar desert is widespread in the Canadian Arctic Archipelago, northern Greenland and the islands of the Siberian Arctic (Korotkevich, 1972). In the New Siberian Islands, about half the surface is occupied by ice caps and the rest by polar desert (Golubchikov, 1996). Figure 2.12 shows its extent based on vegetation criteria. Conventional climate data are inadequate for mapping its distribution due to the general lack of evaporation data and the inappropriateness of standard climatic classification criteria for the Arctic (Bovis and Barry, 1974).
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