The Botany of Iceland - 01.12.1945, Síða 81

THE VEGETATION OF CENTRAL ICELAND
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of a fairly high frequency number. Some of the dominants of associa-
tion 1 have disappeared, but of the new ones that have been added
the following may be mentioned in addition to Alchemilla: Vaccinium
Myrtillus, Rumex Acetosa, and Equisetum pratense; furthermore
Pyrola minor is very conspicuous in this association, which forms a
transition from the associations rich in Geranium to the Alchemilla—-
Anthoxanthum-association. The biological spectra show that the E-
groups are in great majority here. The Ch percentage is also appreciab-
ly lower than in association 1, whereas the H and G percentages are
higher. Number and density of species are alike in both associations.
The two analyses were taken in Víðidalur at c. 450 m above sea-level.
The locality has a southward exposure and a considerable inclination;
the soil is damp, and the snow-covering is probably deeper than in
association 1.
3. Geranium silvaticum—Vaccinium—Anthoxanthum-Ass.
(Tab. XII. A-B, 3-4).
This association differs from the preceding ones in that Alchemilla
has almost entirely disappeared, while Vaccinium Myrtillus and V.
uliginosum dominate physiognomically together with Geranium. As
previously mentioned, these three species are closely related and thrive
under similar conditions. The E percentage reaches its maximum and
the Ch percentage is slightly higher in this than in association 2. Both
analyses are from Víðidalur, height c. 450 m above sea-level, the lo-
calities had a southward exposure, and the snow-covering was distinctly
thinner than in association 1 and probably association 2 also.
4. Taraxacum—Ranunculus acer-Ass. (Tab. X. A-B, 3).
The only analysis from this association was taken in Kringilsárrani
at an altitude of c. 600 m, in a deep snow-patch with an eastward
exposure, but otherwise the conditions are similar to those described
for association 1. Taraxacum croceum ? and Ranunculus acer dominate
physiognomically, in addition there occur many of the same dominants
as in association 1 as also Parnassia palustris. Geranium has entirely
disappeared, and Salix glauca is much less frequent than in association
1. In regard to number and density of species the association may be
coordinated with the Geranium associations, and both species-group
and life-form spectra resemble those of association 1 very much.