The Botany of Iceland - 01.12.1914, Side 131

PHYSICAL GEOGRAPHY
315
witli the birch region, and it probably rarely extends higher than
300—400 metres above sea-level as an aggregate plant-formation; but
several of the different species of which the heather-moor is com-
posed extend far higher up on the mountains without forming any
heath-like associations, occurring as a fewf individuals only. I found
Vaccinium uliginosum at the liighest level (729 metres) near Sydri
Pollar, and also Drgas octopetala at the same place; Empetrum ni-
grum extends to a similar height, and I came across a stunted spe-
cimen even on the top of Botnssulur at an altitude of 1108 metres.
Cassiope hypnoides extends to a great height also; it is found, among
other places, on Hlidarfjall at 790 metres above sea-level, and may
perhaps extend even liigher. Loiseleuria procumbens, on the other
hand, did not occur at a higher level than 400—500 metres. Cal-
luna vutgaris, Arctostaphylus uva ursi and Vaccinum Myrtillus were
found near Myvatn at an altitude of about 400 metres, but I do
not think they extend higher than the limits of the heather moor.
Above the upper limit of the bircb region an osier or a wil-
low region may be said to occur — in the centre of the country
at an altitude of 500—800 metres, in other places somewhat lower —
W’here willows are dominant among the woody plants, although they
have their greatest distribution at a far lower level, in the birch re-
gion itself. At this altitude they do not form any coppice proper,
but occur as flat expanses of low prostrate shrubs. Above the birch
region it is especially Salix herbacea, S. lanata and S. glauca which
are the dominants; Satix phylicifolia retires, although small speci-
mens of the latter also are now and then met with even at this al-
titude. Salix lanata, and to some extent 5. glauca, occupy large
areas of the lower parts ol' the plateau, e. g. in Fjallasveit, Myvatn-
söræfi, Sudurárbotnar, and several other places; they are of great
importance to sheep-breeding, and in some places quantities of wil-
low leaves are gathered as winter-fodder for slieep and cattle; in
the lowest part of this zone Betula nana occurs now and then. In
the centre of the country above 800—900 metres and up to the
snow-line at an altitude of 1000—1400 metres, mosses and lichens
are undouhtedly the dominant plants, although a few’ wúdely scat-
tered phanerogams also occur. Salix herbacea extends also through
this region to the snow-line; here and there, the most hardy of the
previously mentioned rockv-flat plants occur as somewhat scattered
mdividuals, but the main vegetation consists of mosses, although
these do not occur in any great abundance compared with the vast
The Botany of Iceland. I. 21