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Forest regions 57flexuosa. Other at least local constants are Luzulapilosa, Linnaea borealis, Melampyrum pratense andTrientalis europaea. In the bottom layer Hylocomiumsplendens, Ptilium crista-castrensis, PleuroziumSchreberi and Dicranum spp. are prominent.The community is remarkably well-defined as tocomposition by species, but it is greatly changedupon clear-cutting, being rapidly transformed intotall and dense Deschampsia flexuosa growth withprolific Luzula pilosa and establishment of fireweed(Chamaenerion angustifolium), raspberry (Rubusidaeus), etc.About equally important as to area in this regionand generally more productive, is the low-herbspruce forest (Piceeto - Oxalidetum acetosellae)but this is a collective and extremely variablecommunity. Among common constituents, besideOxalis, may be mentioned Anemone nemorosa,Viola riviniana, Rubus saxatilis, Lastrea dryopteris,Maianthemum bifolium (also in transitions to thepreceding association), Melica nutans, etc., and alsothe moss vegetation is richer, including, e.g.,Rhodobryum roseum, M nium affine, Plagiochilaasplenioides and occasionally even Rhytidiadelphustriquetrus. Much of the forests of this type occupyareas that were earlier at least temporarily usedfor grazing or even haymaking, and some partswere burnbeated as late as the nineteenth century.The remaining types of coniferous forest areeither wet, rich in demanding species, or unstable,and cannot be treated here because of their greatvariation and the lack of adequate investigations.Only about ! of the Swedish forest area is in thesouthern coniferous forest region, but about t ofthe standing timber and nearly .g. of the total annualincrement. Due to the more favourable climate andgenerally somewhat better soils, the increment perarea is on an average twice as high as in the northernconiferous forest region. Cuttings have been increasedin recent years but in the southern regionsstill lag behind the annual increment; the reasonfor this is the concentration of the forest industryon Lake Vanern and the Bothnian coast whichwas originally due to the excellent log-floatingcapacity in the Boreal rivers as compared to thealmost complete lack of possibilities for floatingin the more southern regions. The forests of theFig. 7. Spruce forest on a steep slope towards Lake StoraLe (near Kroppsater, Dals-Ed, Dalsland), with favourablemoisture conditions. Note the combination of high productivityof the tree layer with a poorly developed fieldlayer with much Melampyrum silvaticum but not particularlyrich in species. July 12, 1952. Photo G. Lohammar.southern regions are owned by farmers to about75 %, and many of the wood!ots are small, whichcomplicates the organization of forestry operations,but on the other hand, the widespread ownershipof forest among Swedish farmers has greatly helpedthe rural population to resist the economic strainsof our times.The Boreal zoneSuBZONATION.-In a previous paper (1963 a), thepresent author had the opportunity of giving reasonsfor defining the Boreal zone (or Taiga zone) asthat global girdle of which northern Sweden is aActa Phytogeogr. Sueo. 50