fulltext - DiVA

82 SVEN KILANDER18f! SProfile across Nt. Helags(ProvinC'e of Hiiljedalen)N ts/600100Vacc. vitis-idtl!aVa cc. myrt., Sol. virg., Alch. alp.,M a cc. ·t- "d.:A.Wtch., Ath.alp., Nardus, Phleum comm.. ·VI · 1 •Pyr. min., Tri. eur., Euph. frig., Leont. aut.;scattered shrubs: Salix glauca, lan., lapp.,.Jun.. comm.. v. mont./t.OO01200Cirs. het., Cal. oor., Ce um riv., Po t. erecta,{A ndr. pol., Trich. ccesp. ssp. austr. fu rther east)No l. t:tl!r., C'a rex flava, Cy mn. conopseaSalix myrstnif., Carex rostr.; tall hero meadow:Aeon. sept., Lact. alp., Fil. ulm., Va l. samb.2. - 6km/200/000Fig. 4. Profile running south-northacross Mt. Helags in Harjedalen(1792 m, 62°55' N). The uppermostoccurrences of some speciesor communities are indicated.i .uneven deposition of glacial drift there are manysmall lakes which in the lowest 50 or 100 m ofthe low-alpine belt still harbour several vascularhydrophytes. Among them Sparganium hyperboreum,Alopecurus aequalis, Ranunculus reptansand Oarex rostrata occur fairly regularly, the latteralso as .a fen plant. Other species such as Oallitricheverna, H ippuris vulgaris, Equisetum fluviatile andRa/nunculu confervoides have scattered occurrences.Only about 100 m higher up Carex rostrata is almostthe only species met with in lakes or temporarypools.In addition to the species already mentioned thefollowing could be listed as more or less commonin the lowest parts of the low -alpine belt where theyascend some 100 to 150 m: Melampyrum silvaticum,¥· pratense (both in heaths), Menyanthes trifoliata,Oarex magellanica (both in fens), Molinia coerulea,Car ex panicea, 0. flava, Gymnadenia conopsea(these four in meadows and fens, the latter two arecalciphytes) and finally Vaccinium microcarpum(in Sphagnum hummocks of the mires).An early subdivision of the alpine belt wasfounded on the fact that several species reachtheir upper limit at about 1100-1200 m in favourablesituations, at a level -where the timberline isbelieved to have existed during the Post-glacialwarm period (H. SMITH 1920). On mountains moistenough this level is the upper limit of the earliermentioned meadow species Cirsium heterophyllum,Geum rivale and Potentilla erecta (the latter also inheaths), further of Cerastium fontanum ssp. scandicum(in meadows), Trichophorum caespitosum ssp .austriacum, A ndromeda polifolia (both in miresand , moist heaths), Oarex adelostoma (in fens),·t' Galim boreale (in heaths and meadows), finallyOalluna vulgaris (in heaths but irregularly distributedand rare as an alpine plant in the northernparts of the area under consideration). Except for0 erastium and Oar ex adelostoma they all have awide Scandinavian distribution but none is sofrequent within the Scandes, nor has any such aneven upper limit on the mountains as for instanceVaccinium myrtillus or Solidago virgaurea. Some ofthem, viz. Galium, Potentilla, Andromeda andCalluna, are even absent in the alpine region oflarge parts of the Scandes.It can be concluded from the preceding that threehorizons can be discerned in the low-alpine belt.The lowest reaches the upper limit of the tall herbmeadows at about 1050 m, or about 100 m higherin south-facing steeps. The second reaches as far asthe just mentioned species, i.e. to about 1150-1200 m. The upper limit of the third horizon coincideswith that of Vaccinium myrtillus, i.e. that ofthe low-alpine belt as a whole. See Du RrETZ(1925 c, 1942 a, b) about the myrtillus limit.LoW-ALPINE HEATHS.-The most extensive typesof vegetation in the low-alpine belt are heaths,mainly dwarf shrub heaths, except in very wetareas with prevailing mires. As stated above theuppermost occurrences of the heath species V acciniummyrtillus have been regarded as forming theupper limit of the low-alpine belt. This belt delimitationis now unanimously accepted. The bil-.Acta Phytogeogr. Suec. 50