Rit (Vísindafélag Íslendinga) - 01.06.1975, Side 106

in late sumrner, but the sheep seem to prefer the gramineous vege-
tation to C. Bigelowii.
Analysis 1 is from öxnadalur in Bárðdælaafréttur and is taken
in a practically level, semi-moist mire. Analyses 2-4 are from
Gnúpverjaafréttur, all made on substantially sloping stretches of
land. There this sociation was the main vegetation form in large
areas, but in many places it had intertwined with the C. Bigelowii
— C. rariflora sociation. There these sociations may be looked upon
as indicative of the ground water level. Where it is highest the C.
Bigelowii — C. rariflora sociation occurs, but where the level sinks
we find the C. Bigelowii — Salix glauca sociation. Analysis 18 is
from Kringilsárrani at an altitude of about 650 m above sea level.
There the sociation occurs in small patches.
Analysis XIIIx. 6 is from Ketilsstaðir on the border between mire
and Grimmia heath, and consequently the Ch percentage is very
high.
59. C. Bigelowii — Equisetum palustre — Salix glauca sociation
(Tali. XIII A-B 6-11)
The observations to be discussed here are all from Bárðdælaaf-
réttur, mostly from its lower regions, that is, the southem part of
Fljótsheiði where this sociation is common, but does not cover
large areas. It is not possible, therefore, to comment on its distri-
bution elsewhere, but I believe it to be fairly widely distributed.
Despite the fact that Salix glauca is a character species here, the
sociation is related to sociations 56 and 55.
Apart from the character species the following are most widely
distributed: Polygonum viviparum, Yaccinium uliginosmn, Cala-
magrostis neglecta, Equisetum variegatum, Eriophorum angusti-
folium and C. nigra are fairly extensive in places and C. rariflora
is dominant in one analysis. Betula nana is conspicuous in some
observations, although it rarely occurs in the C. Bigelowii associa-
tion. The biological spectrum is surprisingly homogeneous. Here
the Ch percentage is at its maximum in the C. Bigelowii mýri,
whereas the G percentage probably has the lowest average. As be-
fore, however, it is the most abundant lifeform. 'Where this so-
ciation occurs the ground is fairly damp, similar to that of 56,
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