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66
I. PHYSICAL GEOGRAPHY.
days — by forest fires. The fire kills the spruce, but often leaves the pine
uninjured; and afterwards this last, together with the common birch, reproduces
itself in the ground fertilized by the ashes. The development to pure
spruce-forest, however, has in many places been hastened by the fact that pine has
been cut down while the spruce has been let alone. This method of
woodcutting was especially common in former days. In the coast districts and in the
southern parts of the region there occur coniferous forests with pine and spruce
of about the same age. In many districts — e. g., in the Silurian of Jämtland,
in southern Lappland, and in the district between the Öre and Lögde rivers etc.
— pure spruce-forests occupy vast areas where the pine has been so completely
ousted that it is positively a rare tree. The spruce-forest of Norrland is marked
by a soft brownish-green covering of moss, above which rise low dwarf-shrubs
such as blueberry, linnea (Linnæa borealis), different species of pyrola and
lycopodium; and here herbs and grasses are somewhat more prominent than in
the pine-forests. A type of wood peculiar to the northern region of coniferous
forests is the swamped spruce-forests that occur both on the more level ground
and also on the slopes of the moraine shelves. The predominant plants in the
ground-covering are bog-moss (Sphagnum), bear moss (Polytrichum commune) and
such plants as thrive in moist peat-bogs, e. g., cloudberry (Bubus chamæmorus),
horsetail (Equisetum silvaticum), sedge (Carex globularis). The spruces are slow
growers, the crowns are meagre and thin, wrapped in veils, of gray and black
lichens. In the Silurian of Jämtland and in southern Lappland there frequently
occur spruce-forests rich in herbs, where high-growing luxuriant herbage forms
a rank undergrowth.
Along the great rivers, round the streams and brooks, the covering of
coniferous forest is broken by light deciduous forests, chiefly formed by the common
birch and the gray alder (Alnus incana) with a mixture of sallows, high-growing
osiers, bird-cherries and rowans. In the not too dense shade there often
flourishes a rich undergrowth of broad-leaved herbs and soft grasses.
The Southern Region of Coniferous Forest begins, as has been
mentioned before, at the northern limit of the oak. The enormous
covering of forests which once clothed this part of the country also has
here had to give way in a higher degree to cultivation. The vast clay
plains in the vale of Mälaren, in the lowlands of Närke, and the plains
of Östergötland and Västergötland are amongst the most important
agricultural districts in the whole of Sweden; and, broadly speaking,
cultivation has laid claim to the greater part of the country below the
highest marine limit. As in the northern region of coniferous forests,
the uncultivated land consists principally of coniferous forests, formed of
pine and spruce; but here we have also a new element in the
vegetation, viz., the oak flora, which in the northern region was but feebly
represented, chiefly by mere remnants. To the oak-flora belong chiefly
a numbers of true deciduous trees, such as the oak itself (Quercus
pedunculata), the ash (Fraxinus excelsior), the elm (TJlmus montana), the
linden (Tilia ulmifolia), the maple (Acer platanoides), the hazel (Corylus
avellana), the blackthorn (Prunus spinosa), the hawthorn (Crataegus
oxyacantha), the honeysuckle (Lonicera xylosteum) etc. With these are
associated a large number of grasses ond herbs which thrive best in the
woods formed of the true deciduous trees.
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