fulltext - DiVA

ASPECTS OF THE NORTHThe BorderlandBy SVEN FRANSSONGeneral and historical aspectsIn his Flora svecica (1824-26), G6RAN WAHLENBERGdivided Sweden into several phytogeographical regions.One of them, Regia Quercus, was said to bebounded toward the north by the northern limitfor Quercus robur. This is a clear establishment ofa boundary that has frequently been referred to inthe Swedish phytogeographical literature, variousdefinitions and terms having been applied.To W AHLENBERG, the oak region borderline wasonly one of several regional boundaries. The firstto regard it as the most important line of separationbetween southern and northern vegetationseems to have been MYRIN (1832, p. 175). Hisopinion was rapidly accepted, e.g. by ELIAS FRIES(1856, 1864), and still is shared by most Swedishbotanists. For a fuller treatment of the historicalaspect, see MAGNUS FRIES (1948).Regarded from a European viewpoint, theboundary separates two floristic provinces, that ofCentral Europe and that of Northern Europe andWest Siberia (cf. Du RIETZ 1925 c, pp. 6-9 andPI . I, SJORS 1956, pp. 6-7, and others), or, withregard to vegetation, two vegetational regions (thesouthern and northern coniferous forest regions)that are parts of different zones, viz. the Boreonemoraland the Boreal zones (to use a terminologyrecently advanced by SJORS, 1963 a, pp. 111-121).Due to its general significance but also to itssharpness in Sweden, great emphasis is laid on thisdifference in several Swedish phytogeogra phicalworks (in addition to ,the mentioned paers, seee.g. Du RIETZ 1933 a, p. 56, 1935 a, 1950e, 1951 b,195 1953b, 1964, v. PosT 1933, SJ6Rs 1948 a, 1956,1958, AHLNER 1950, HARD AV SEGERSTAD 1952,SELANDER 1955).In contrast to more equalized conditions in Finlandand Russia, the phytogeographical transitionin Sweden is condensed within a narrow belt. However,even in Sweden this belt is a zone of divergence(M. FRIES 1948, p. 51) rather than a singleline. This zone of divergence coincides with steepgradients in several climatic functions. The climaticgradients, in turn, are to some extent strengthenedby a considerable difference in level and landforms(op. c., p. 57). In addition, the types of Quaternarydeposits are also largely different. Secondary effectsshould not be disregarded: in particular soil development,the different impact of agriculture, grazingand forestry practices on land vegetation, anddifference in nutrient quantities released to thefresh waters.The complicity, but also the coincidence of thesegeomorphological, climatic, biogeographical andcultural divergences led SER.NANDER (see furtherM. FRIES 1948, p. 56) to recognize the intrinsicsignificance of the borderline in all these aspects,as evident from his pseudo-classical term, the limesnorrlandicus. Du RIETZ (1935a,, 1950e, 1951 b, 1952,1953 b, 1964) has repeatedly tried to find a moreadequate designation, and finally proposed a Swedishexpression meaning "the natural borderlinebetween North and South Sweden."Geomorphological and cultural features of the landscapeThe geomorphology of interior North Swedenwas dealt with by STEN DE GEER (1910, p. 4, 1926,p. 126), and in his latter work this area was subdividedinto several landform regions, the southernmostone, that of "Bergslagen", being characterizedas a "chequer plateau land with broad valleys".A.ota Phytogeog.r. Suec. 50