Full resolution (JPEG) - On this page / på denna sida - First part - I. Physical Geography - 4. Vegetation. By Lector A. Nilsson, Ph. D., Institute of Forestry, Stockholm
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54
I. PHYSICAL GEOGRAPHY OF SWEDEN.
meters broad and even less. Its lower limit, assumed to be where the
pine-trees begin to appear more commonly, is farthest north hardly 400
meters above sea-level but ascends gradually towards the south to
about 900 meters.
In certain localities where the ground is calcareous, birch-woods rich in
plants occur, especially marked by a luxurious carpet of high-growing, large-leaved
plants, such as wood-crane’s-bill (Geranium silvaticum L.) and alpine sow-thistle
(Mulgedium alpinum Less.) On the rest of the region with dry and meagre soil,
birch-heaths alternate with mossy birch-woods, which woods, as regards the
surface-covering, nearly coincide with corresponding pine-woods. Where the ground
is moist, it is occupied by extensive bogs marked by numerous species of sedges
and cotton-sedges (Eriophorum) together with Scirpus cæspitosus L., sparely
intermingled with dwarf-birch, bog-whortleberry (Vaccinium uliginosum L.), Andromeda
polifolia L., and others, and a bottom-covering, in which leaf-mosses, as
Amblyste-gium and Dicranum, are more abundant than bog-mosses (Sphagnum). Lakes,
streams, and bogs are often bordered by vast willow copses, chiefly consisting of
the above-mentioned species of Salix together with Salix nigricans Sm. Flowering
waterplants are but sparely found.
The Firwood region occupies the north of Sweden below and south
of the birch region. Its southern boundary coincides with the northern
boundary of the region where the oak is commonly found, and stretches
from Söderhamn along the shore to the Dalelf, and thence in
southwesterly direction to lake Skagern, from where it bends northwards
to the upper Fryken lake and then southwards again into Norway.
The woods are composed of pine (Pinus silvestris L.) and spruce
(Picea excelsa Link), frequently much mixed with birch in the parts of the
region nearest to the Birch region, and also in other localities which in
later times have been swept by fire. Besides firwoods in various states
of development, peat-bogs and, below the uppermost marine limit,* röck
associations decide the character of the landscape. In the valleys of
the Torne-, Great Lule-, Pite-, and Skellefte-rivers and in a few other
places the boundary-line of the firwood region is occupied by pine,
in other valleys and everywhere along the watersheds by spruce. Close
to the Birch region a narrow belt of spruce woods is ordinarily to be
found. In the western part of Ume Lappmark and Jemtland this belt
expands into a spruce district many miles in width. Large spruce
districts are also found between the river valleys along the watersheds.
These spruce districts are characterized by mossy and boggy spruce
woods alternating with peat-bogs. The country along the larger rivers
is commonly occupied by pronounced pine districts, in which spruce is
found in depressions and along the brooks. While in the interior of
the country the pine and spruce woods are distinctly separated, mixed
firwoods are peculiar to the coast, increasing going southwards.
Cultivated districts of any extent are, as a rule, only found along the
river valleys below the marine limit.
* The districts formerly submerged by the glacial sea.
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