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Forest RegionsBy HUGO SJO RSA country of forestWith more than half its area tinder forest, Swedenis next to Finland the most forestry-mindedcountry of the world. The forests are one . of thenation's principal natural resources, and its leadingsource of wealth, as far as external trade is concerned.A visitor to Sweden from a more denselypopulated country-especially an observer used toopen scenery· of West Europe-is usually eitherimressed or depressed by the sequences of mileshe frequently has to pass between the inhabitedareas, through stately but sight-reducing, evergreenbut gloomy coniferous forest. Alternationbetween two conifer species and change betweendifferently aged stands are often the only obviousvariation. Only here and there he will be enlightenedby the brighter colour of a grove of birch or aspen.Occasionally he passes one of the nowadays oftenextensive clear-felled areas. To save the touristicfame of the country, glimpses of a lake frequently.break the monotony produced by a percentage offorest usually varying between fifty and eightyfive.'I'he road-bound traveller will hardly realize thatopen bogs and fens cover as much as about 1/7 of thecountry, much more than the lake area which isover nine per cent.The arable land of Sweden is comparable to thelake area. There are four main agricultural districts-Skane (especially the S and W), the area to theS and SW of Lake Vanern, central Ostergotland,and the lowland adjacent to Lake Malaren. Elsewherethe percentage of fields is low, usually aboutten to twenty in the south, a few per cent · only insouthern and coastal N orrland, and less than oneper cent in the northern interior. Fields could bebrought under the plough only where bouldersand stones were absent or scarce, and in many partsActa Phytogeog1·. Suec. 50are nearly confined to water sediments, clayey tills,and drained fen peats; only in Sma.land and someother provinces have large areas of coarse driftbeen cleared of boulders with immense labour. Inconsequence, the forested areas largely coinoidewith the coarse tills, the gravelly and partly thesandy glaci-fluvial sediments, and, with poor woods,some of the rocky areas with thin soil.Biotic regionsThe indigenous-natural or semi-natural-ecosystemsof any extensive area show a zonation dueto regional climate and physiography. Vegetation,animal life and environment thus combine to formbroad biotic zones that in some cases constituteeither almost entire or fragmentated girdles roundthe globe. In most cases, these girdles can bedivided into biotic regions of moderate longitudinalextension, where floristic and faunistic conditionsare less heterogeneous than in the girdle as a whole .Being sectors of the biotic zones, these regionsusually show a zonal arrangement, although notnecessarily in a south-to-north direction. For Sweden,altitude is equally important, and the bioticregions of the mountains are parts of verticallyarranged biotic belts. See further, e.g., Du RIETZ(1930b), SJORS (1963a).Biotic regions, by definition, are units on theecosystem level (SJORS 1955), although they constituteextremely complicated and heterogeneousecosystems. As the faunistic arrangement is lessdefinite than the vegetational zonation (owing tothe mobility and migration of many animals, theinstability of their populations and other factors),botanists are usually ahead of zoologists in definingregions. Botanists who distinguish vegetation regionsrather than biotic regions may also justify their