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Forest regions 49professionalism by the primary role played by vegetationin giving food and shelter to animals (althoughin some biotic regions of the world animalsare equally important in controlling the compositionand stature of vegetation). In Europe, manand his domestic animals are more important agentsthan the native vertebrate fauna; thus the latteris hardly of primary regional importance, as faras the regions of Sweden are concerned.Floristic provinces have often been considereddifferent from vegetation regions (Du RIETZl925 c, etc.). In Sweden, endemism is insignificantand there are no definite barriers that check plantmigration. As the flora is young (at least on Swedishterritory), direction and time of immigrationmay have some importance, but this is unlikelyto create floristic boundaries. On the whole, adivision according to distribution areas is lessdefinite than is the zonation of vegetation, butit is also more many-sided. In particular attentionshould be paid to a west-to-east gradient in theflora-mainly in southern Sweden but also farthernorth, see S. RUNE's article-and to the richermountain flora of the northern Swedish Scandes.These two floristic gradients are not accounted forin the usual system of vegetation regions, althoughboth have a certain importance for the compositionof some plant communities.In the following, biotic regions and vegetationregions are regarded as identical when Swedishconditions are dealt with. As far as infra-alpineSweden is concerned it will moreover be permissibleto refer to the biotic regions as forest regions.But this does not imply that a forest region issimply defined by a standard composition of theforests. First, there is nothing like a standardforest community, for a closer examination of anyextensive forested area reveals a multitude of vegetationtypes. Secondly, vegetation without a treelayeris equally characteristic of the region towhich it belongs.It has long been the practice of Swedish botanists. to discuss and name the regions of our countrymainly from a Fennoscandian point of view.However, this is perhaps too isolationistic, andthanks to much regional work recently done in theU.S.S.R. and in Canada, a wider outlook on theFig. 1. Swedish forestsas a percentage of theland area. From A Geographyof Norden (adaptedfrom Atlas overSverige).zones to which our regions belong (as longitudinalsectors) is now possible. The choice of terms forthese zones has been briefly motivated in an earlierpaper (SJORS l963a), to which reference is alsomade regarding this wider outlook and regardingsome of the relevant literature.The N emoral zoneIn Western and Central Europe, spontaneousforests are formed almost exclusively by deciduous,broad-leaved trees, except for some areas wherepine (Pinus silvestris) has survived (it had a widedistribution in the early Post-glacial). This zone isrepresented in Sweden (by its northern subzone)only in the extreme south and along the west coast.The region in question is usually called "Thesouthern deciduous forest region". It is customaryto give the south-western limit of spruce (Piceaabies) forest as the regional boundary towards theinland. Unfortunately, this limit is only knownfrom earlier records and is now almost impossibleto reconstruct because of the extensive planting ofspruce to the south and west of the original boundary.Even though a planted or sown spruce forestcan usually be distinguished easily from one grownActa Phytogeogr. Suec. tiO