The Botany of Iceland - 01.12.1942, Page 68

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JOHS. GRONTVED
Equisetum pratense
Carex rigida
Rubus saxatilis
Armeria vulgaris
Poa alpina
Galium pumilum
Trisetum spicatum
Cardaminopsis hispida
Silene acaulis
Thalictrum alpinum
Viscaria alpina
b. Birch woods. The only tree of any importance in the
woods of Iceland is Betula pubescens. In some places Sorbus aucuparia
also occurs but always only as scattered individuals. Salix phylicijolia
is often associated with the birch, but usually only grows as a shrub
or small tree. The greater part of the birches merely form brushwood,
or are stunted or crooked trees; only in a very few places are there
today what may be called woods to be found in Iceland. Comparatively
well-grown trees are, however, still to be found, as remains of woods
which have formerly been far more extensive. From the Icelandic Sagas
it appears plainly that at the time of colonisation there were large woods
throughout the country, but the reckless use of wood for fuel and
charcoal-burning in the past centuries has been the cause of partial or
complete destruction of many of these woods.
The soil on which the Icelandic woods are standing is mainly com-
posed of very fine material, loam or tuff-dust (móhella), with only a
thin upper layer of mould. It is in fact an exceedingly favourable soil
for plant-life, but owing to its loose structure it may easily, when exposed
to wind or water, be carried away from the roots of the trees, and the
wood will thus be liable to be destroyed.
The average height of Betula pubescens is from 1 to 3 m, but in
a well-grown birch-wood the individuals may attain a height of even
up to 10 m, on an average about 5 m. In Hallormsstaóaskógur I have
seen trees which had a height of 10 m, the trunk having a circumference
of about 80 cm.
Wigge (1930, p. 127 et seq.) points out that the northern limit for
the birch in Iceland is not climatically determined, thus Iceland must
be regarded as lying entirely south of the polar tree-limit. According
to Thoroddsen the actual Iimit of the wood takes a course which leaves
important parts of the north-western, northem and north-eastern country
practically without the wood-birch.
Of the more important birch-woods thc following may be named:
Hallorinsstaóaskógur at Lagarfljót in E. Icel.
Fnjóskadalsskógur and Þórðarstaftaskógur in Fnjóskadalur N. Icel.
Bæjarstaðaskógur below Jökullfcll in öræfi S. Icel.