The Botany of Iceland - 01.12.1945, Blaðsíða 123

THE VEGETATION OF CENTRAL ICELAND
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of c. 700 m, southward exposure. A solifluction phenomenon may often
be observed in this locality. Small terraces, c. 20-50 cm high, are found
on the rather gently sloping hillside. The surfaces of the terraces are
almost entirely devoid of vegetation, but their front margins are almost
covered with vegetation, so that, when viewed from the side, the land
looks as if it were covered by green and grey stripes. The following
species were found on thc edges of the terraces: Salix herbacea, Fesiuca
rubra, Silene ac.dulis, Saxifraga oppositifolia, and Carex rigida. Analysis
XXII, 5 was made on the mountain Laki on Síðumannaafrjettur at an
altitude of c. 700 m on a slightly sloping surface.
2. Salix herbacea—Elyna Bellardi—Polygonum viviparum-Ass.
(Tab. XXI. A-B, 1).
Almost the only difference between this and the preceding associa-
tion is that Elyna Bellardi is a dominant here. Otherwise the two as-
sociations agree both in species composition and in the biological spec-
tra. The analysis was made in Fagradalsfjall near analysis XXI, 2, but
this locality is slightly more sheltered from the wind than the other,
which is at once manifested in a closer vegetation. The association is
distinctly transitional to the brekkur vegetation.
3. Salix herbacea—Dryas octopetala-Ass. (Tab. XXI. A-B, 6-7).
The association differs from the other melur associations in that
Dryas octopetala is dominant together with Salix herbacea and Poly-
gonum viviparum. Both analyses were made on Snæfellsöræfi at alti-
tudes of 630 and 680 m respectively. They were made in similar locali-
ties, that is to say, on much exposed melur ridges where there is no
shelter and the snow-covering must be rather thin. The vegetation was
very scattered even compared with the melur vegetation in general.
4. Salix herbdcea—Saxifraga oppositifolia-Ass.
(Tab. XXII. A-B, 1-2).
In addition to the character species, Polygonum viviparum is the
only species which here exhibits a noteworthy frequency number.
Analysis 1 was made on a low boss of rock near Jökuldalir, at c. 700 m
above sea-Ievel, while analysis 2 is from Landmannahellir, altitude c.
620 m, from a slope exposed towards the southwest. Both localities are
much exposed and the vegetation scattered.