The Botany of Iceland - 01.12.1945, Blaðsíða 105

THE VEGETATION OF CENTRAL ICELAND
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found near the southeastern side of the mountain, where the soil of
the shrub heath is driest. The surface is slightly inclined and entirely
without knolls. The species of Salix are so vigorous that they come
close to Salix scrubs in the same sense as is recorded from the mountain-
ous areas of Scandinavia and Greenland. Salix glauca and S. lanata
show about the same development as regards density and degree of cover-
ing, they are about 50 cm in height. Among them there occurs a dense
ground vegetation of Gramineae and in addition especially of Equise-
tum pratense. The association is closely related to the brekkur forma-
tion, but is poorer in species. The snow-covering is probably relatively
thick. Noteworthy is the high E percentage, especially the Ei percent-
age, of the association, but otherwise the latter group hardly occurs
in the shrub heath. The association was not noticed in other parts of
my area of investigation.
8. Salix herbacea—Carex rigida-Ass.
(Tab. XV. A-B, 5; XVI, A-B, 6).
The association resembles the snow-patch formation in several
respects, but the conditions in the localities in which it was observed
show that we cannot speak of more than a normal snow-covering here.
The vegetation is hardly closed in the herb layer, mosses being very
prominent in the ground vegetation without the latter assuming the
character of a moss heath. Salix herbacea is entirely dominant physiog-
nomically, while C. rigida is of more scattered occurrence. Analysis
XV, 5 was taken on Snæfellsöræfi at an altitude of c. 700 m, on a
level surface some way up the mountain side. Analysis XVI, 6 is from
Jökuldalir, from a locality at the foot of the mountain, but the as-
sociation is also found higher up the mountain side. I suppose that it
is one of the boundary associations of the shrub heath. The biological
spectra show a high A percentage. The association is of rare occurrence.
9. Salix phylicifolia—Festuca rubra-Ass. (Tab. XIV. A-B, 6).
The only analysis I made in this association is from Þorlákslindir,
at an altitude of c. 520 m.; it was taken in a S. phylicifolia scrub, which
forms narrow rims on either side of the brook that flows through the
oasis from the spring. The scrub is 50-75 cm high. The dominant
species in this association besides the character species, is Galium verum.
Some other herbs are of scattered occurrence, for instance Geranium