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For est regions 51oak and beech here slowly give way to ash and elm,partly via an intermediate state with muchshrubbery.Carpinus betulus is fairly common in the southernbut absent in the north-western part of this region.It occasionally forms small woods, e.g. at Halltorpon bland and Stenshuvud in Skane. Tilia cordatais widespread, but T. platyphyllos, a markedlysouthern species, has only a very limited andisolated outpost occurrence in northern coastalBohuslan. Ligustrum vulgare (a shrub; in coastalBohuslan) and Acer campestre (in Skane) are otheroutpost species.A difficult problem is the competition betweenbirch, oak and beech. On poor light soils birch(mainly Betula verrucosa) is usually dominant (ifnot replaced by pine) but not rarely the two oakspecies (Quercus robur, Q. petraea, often also hybrids)take the lead. According to H. WEil\:IARCK (l947 b)Q. petraea is confined to non-calcareous soils. Foroak regeneration, a fairly open stand but temporalabsence of grazing is almost a prerequisite. Someoakwoods, however, have grown from stump shoots,like the coppice woods of Britain. The longevity ofthe oaks will perhaps give them a better chance ofsurvival than the birch. Wherever beech can growup well, it will become a serious competitor toboth birch and oak. Beech regenerates poorly in aclosed forest of its own species and in too open sitesit is often damaged by frost or animals, but moderatelyclosed stands of oak' or other species seemto give the beech seedlings a better start in life.This would occasionally lead to an alternationbetween generations of different tree species. Earlieralso pigs turned out to feed on beech or oak mastprovided good germination conditions for beechand it is believed that many of the present closedbeechwoods originated in this way. However, themost important factor was man; whereas beechforests were preserved on the large estates, thefarmers did not hesitate to exterminate the beech,in order to get better grazing.On soils of poor or medium quality in interiorSkane or Halland, pine, birch, oak and beech occurspontaneously in alternating stands, probablyirrespectively of the primary soil type. The beechwoodon poor soils is of a type with mor humus and,(;> Regions100 kmCJAipine- BirchwoodNort hern ConiferousSouthernConiferousr::-:::1 Southernt..:::.:.:..:.. DeciduousFig. 3. The forest regions of Sweden. The birchwood region(subalpine belt) and the northern coniferous forest regionform a sector of the Boreal zone. The stippled parts are theareas with predominance, more or less, f the upper, prealpine(montane) subzone, corresponding to the Subarcticor Northern Taiga further east. The southern coniferousforast region (with oak) is a sector of the Boreo-nemoraland the southern deciduous forest region a part of theNemoral zone. Seemingly spontaneous beech groves abovethe beech forest limit are grossly indicated by rings, butmany more exist. Adapted· from Skogen och skogsbruket.Acta Phytogeogr. Suec. 50