Description of Fennoscandian Tundra Ecosystems

Abstract

The tundra landscape of Fennoscandia is mostly alpine. The southernmost areas above the tree line, with annual mean air temperatures below 0° C, are found at about 59° N in southern Norway. A mountain range runs along the entire Scandinavian peninsula up to about 70° N and is geologically part of the Caledonian mountain range, intensely folded mostly in the Silurian period (Holtedahl, 1960). The highest mountains are found in the western districts. An eastward tilt of an imaginary surface connecting the summits was caused by a stronger land upheaval during the Tertiary period in these areas than further east. Generally, therefore, higher mountains and more mountainous habitats for all life are found in Norway than in any of the other Fennoscandian countries (cf. Somme, 1968). The drainage divide is close to the western coast and the mountain slopes are therefore steeper to the west than to the east. During parts of Pleistocene time all Fennoscandia was covered with ice except for a few refuges in extreme maritime areas, and possibly also on a few of the highest mountain peaks. Glaciers are found even today all along the length of the mountain range, and. they strongly influence the ecosystems near them. There are several plateaus in the mountain areas, partly incised by water erosion and abraded by ice movements. The ice movement caused formation of several moraines, and the quaternary deposit is often transported far from its geological origin (HOLTEDAHL, 1960; Lag, 1965; Rankama, 1965; Somme, 1968). Above the uplands rise snowy, high peaks, particulary in the central region of southern Norway. In Sweden most of the mountains are found along the Swedish-Norwegian border (a belt up to 100 km wide).