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220 GUNN AR WISTRANDFig. 3. View from a low fell .. Scattered 15 to 20 years oldpines on the heath give evidenceof an amelioration of the climateduring the last few decades.Stuor Vuosmavare (650 m), Wboundary of Muddus NationalPark, Lule Lappmark. Aug. 2,1947. Photo H. Sjors.of conifers as scattered shrub-like trees, saplingsor seedlings far up in the alpine belt. Pine saplingsand spruce shrubs have been found more than 800m above sea level, while in the Scandes they rarelyascend beyond 600 m and are absent in the westernmostparts of the valleys even at a considerablylower altitude.On low fells with little or no birchwood the levelof the tree-line has probably fluctuated to someextent also in the last millenium owing to forestfires in the upper part of the spruce belt. Stumpsand logs of spruce with marks of fire have in somecases been found in the present alpine belt.Because of their comparative youth, the alpineplant communities of the isolated fells are possiblynot yet definitely established. Prevailing in thealpine belt are different kinds of dwarf-shrub heaths(Du RrETZ l942a). Nearest to tops and hillocks,on areas where the snow melts away early, we findEmpetrum heath, whereas V accinium myrtillusheath prevails in sites with longer lasting snowcover.Locally Phyllodoce coerulea forms a sociationof its own, and Calluna vulgaris also plays an importantpart. Among other species, included in theheath vegetation, Arctostaphylos alpina and Loiseleuriaprocumbens may be mentioned.Grass heaths cover only small areas. On the verysummits we find a special kind of heath, rich ingrasses and with several anthropochores as constituents.Probably this heath is influenced by reindeergrazing. In depressions with the character of snow-beds there are fragments of a N ardus stricta heath.Meadow vegetation is also uncommon. Along theborders of brooks (including such that run dryearly in summer) and likewise in some well-draineddepressions there are narrow strips or spots of lowherbmeadow, in most cases a kind of Ranunculusacris meadow. High-grown herb communities arelacking a hove the tim berline.In the flora of the isolated low fells there areseveral alpine species. Some of these are to be foundonly below the timberline, usually in precipices;others, however, are restricted to the treeless alpineareas. Of the latter some are constituents of thepredominating heath vegetation. These species arealso able to exist in forests of different kinds andmay have grown on the hills during the forestperiod, or else they may have migrated to thealpine islets through the surrounding woods. Otherspecies are restricted to the small snow-bed areas.They are not able to grow below the timberlineand a migration through the woods is thereforenot possible. In order to reach their present localitiesthey must have carried out a jump-wisedispersal over fairly long distances (in some cases80-100 km). Part of the way they may have followedthe waterways, but as the species involvedare hardly ever found along the rivers within thesilvine belt, water as the means of dispersal seemsrather improbable. The species in question are suchas Athyrium alpestre, Luzula arcuata, Trisetumspicatum, V ahlodea atropurpurea, Carex Lachenalii,Acta Phytogeog1-. Suec. 50