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84 SVEN KILANDER. HIGH-ALPINE ZONATION.-At still higher levelscliffs and boulder fields cover large areas butusually there are some patches of soil even close tothe highest summits. In the vicinity of the 1600 mcontour the vascular vegetation is no longer conti­mous, occurring as fragments or even single individualsof vascular plants. This is the beginning ofthe high-alpine belt. In the southern Swedishmountains only three massifs reach this belt, Mt.Helags (highest summit 1796 m), the Sylarna Mts.(1762 m on the Norwegian bqrder) and the Mts.Harj angsstotarna ( 1626 m).In the high-alpine belt of the Lapponian mountainsDu RIETZ (1925 f, p. 73) recognized threehorizons, which can also be found in these moresouthern mountains (KILANDER 1949).In the lower horizon Salix herbacea is an importantdominant beside Ranunculus glacialis. Moreor less regularly found are here:A ntennaria alpinaCardamine bellidifoliaCa1·ex BigelowiiCassiope hypnoidesDeschampsia alpinaErigeron uniflorumFestuca viviparaGnaphalium supinumLycopodium selagoLuzula arcuataL. spicatal11inuartia bifloraOxyria digynaPoa alpinaPoa flexuosaP. femtlandicaRanunculus glacialisR. pygmaeusSalix herbaceaSaxifraga cernuaS. groenlandica (on cliffs)S. nivalis (on cliffs)S. oppositijoliaS. rivularisSibbaldia procumbensSilene acaulisTaraxacum croceum coil.Trisetum spicatumIn the middle horizon Ranunculus glacialis is theonly dominant. It has little competition from thefew other species of the field layer and may occasionallyoccur in considerable abundance. Thishorizon has a vertical extension of only about 50 m.In the highest horizon, i,n particular on thesides facing north, vascular plants occur only asscattered individuals except on the highest summits.On Mt. Stora Helagsstoten this horizon beginsat about 1640 m (in the most favourable exposureat about 1755 m), and in the Sylarna Mts. fromabout 1590 m upward (in favourable exposure1710 m). The highest altitudes reached by vascularplants are considerably higher: Poa flexuosa at1792 m, Ranunculus glacialis at 1782 m and Poajemtlandica at· 1759 m.The mountains to the north, east and southThe southernmost Swedish mountai;ns form anorth-eastern outlayer of a much bigger mountainousarea in southern Norway. Between thissouthern area of high mountains and the stillhigher mountains in central and northern Lapplandis a wide part of the mountain range, in middleand northern Jamland and southern Lappland,where the mountains only reach moderate altitudes.Here only isolated groups of mountains and singlesummits reach the middle-alpine belt or close to it.This area has a markedly oceanic climate andits flora, chiefly within the wooded belts, besidenumerous suboceanic · bryophytes and lichens, ·contains such species of coastal Norway asN arthecium oSS'ifragum, Blechnum spicant and therare species Juncus squarrosus and Lastrea oreopteris.The showy Saxifraga cotyledon is met withon cliffs in the low-alpine and subalpine belts.Within the reach of the suboceanic climate Cornussuecica is · common and ascends quite a distanceinto the low-alpine belt (see Fig. 1). In more subcontinentalareas it is absent above the timberline.Within the alpine belts the oceanic influenceleads to great accumulation of snow, and due tolower summer temperature the thawing is comparativelyslow. Therefore snow-beds are widespreadand they occur even below the .timberline.The forest limits fall strongly towards the areaunder oceanic influence. The same is true of thevarious limits within the alpine belts.The fringe of low mountains which borders thesouthern mountainous area towards the east andsouth is made up of hard rocks very poor in lime,including quartzite, sparagmite, granite and sandstone.The vegetation and flora in consequencehave an utterly poor appearance, dwarf shrub andlichen heaths prevailing completely in the alpineregion. See G. SAMUELSSON (1917) for Dalarna.The frequency of snow-beds is small, but in theOviksfjallen Mts., their vegetation has been studiedin det.ail (GJJEREROLL 1949). Alpine species areunlikely to reach their potential upper climaticlimits on mountains of tis type.Acta Phytogeogr. Suec. 50