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The south-western dwarf shrub heaths 127Fig. 3. Oalluna vegetation of thesouth-eastern type surrounded bya lowgrown oakwood of "heath"type. Rocky area W of LakeFarskesjon, Jamjo, Blekinge. Aug.7, 1958. Photo B. Berglund.species alternating as dominants. Carex w·enariaand Deschampsia flexuosa are usually associated,locally scattered individuals of Polypodium vulgare,too, but few other species. In the bottom layerHypnum ericetorum, Pleurozium Schreberi andCladonia spp. occur. The Vaccinium spp. and manyother species characterizing the Calluna- Vacciniumcommunity are absent. Cf. BocHER (1943 : "Empetrionboreale") and GIMINGHAl\1 (1961, Table 4,1964, p. 264). A closely related heath community,usually lacking Calluna but with much Salix repensand scattered dune species is found on dry sandflatsor north-facing dune slopes, e.g. in southernHalland (BocHER 1943, Table Sa, ARDO 1957,GIMINGHAl\1 1961, Table 6). Cf. also the West­European ''Saliceto repentis-Empetretum'' (TuxEN1955). It seems probable that these heath communitiesdevelop from the Corynephorus communitywith which they often alternate. See furtherBENGT PETTERSSoN's essay "Maritime sands". Thehumus layer is thin (2-5 cm) with a pH of about5.0.CALLUNA-NARDUS COMMUNITY.-With increasingheight of the sub-soil water-level the more orless continuous cover of Calluna vulgaris in aCalluna- Vaccinium community breaks up intopatches between which graminids dominate, esp.N ardus stricta. Investigations on this vegetationhave not yet been published in Sweden, but itmight be treated as a separate Calluna-Narduscommunity. The following species seem to betypical: Calluna vulgaris, Erica tetralix, Achilleaptarmica, Anemone nemorosa, Galium saxatile,Potentilla erecta, Pedicularis silvatica, Agrostiscanina, Carex nigra, Deschampsia flexuosa (in lowdegree of cover), Festuca ovina (do.), Juncussquarrosus, N ardus stricta, Sieglingia decumbens,Trichophorum caespitosum, A ulacomnium palustre,Pleurozium Schreberi, Polytrichum commune, Rhytidiadelphussquarrosus and Lophocolea bidentata(ERICSON, unpubl.). The proportions between thespecies depends on several conditions, perhapsabove all the intensity of grazing. With increasingintensity Calluna vulgaris is reduced while N ardusand Juncus squarrosus are favoured. In still moisterlocalities this community is replaced by a Carexpanicea-Nardus stricta meadow vegetation.This Calluna-Nardus community seems to beclosely related to similar vegetation in westernEurope, e.g. Nardo - Galion saxatilis (PREISING1949). In South Sweden it has probably the samedistribution as the Calluna- Vaccinium community.To the east and north there is a gradual transitionto Nardus communities without western species ofthe Erica group. Cf. also ALMQUIST (1929, pp. 192-194).The Calluna-N ardus community is usually found..t!c"ta Phytogeog.1·. Suec. 50