Rit (Vísindafélag Íslendinga) - 01.06.1975, Blaðsíða 128

for example, have been among the dominant species in some so-
ciations of the highland mires. Vaccinium uliginosum, Betula nana
and Empetrum hermafroditum are also fairly frequent in many
parts. In some mire-formations one or more of those species become
so prominent that they characterise the mire more than the Cy-
peracéa which accompany them and are normally characteristic of
mire vegetation. I have referred to mires of this kind as shrub-mires
(Steindórsson 1943 and 1951). Either V. uliginosum or B. nana
becomes dominant in the shrub mire and its sociations can be
named after those species. It is often hard, however, to draw a
clear line between sociations. Although the shrubs dominate in the
physiognomy of the mire and even in covering, their frequency
is often the same as in the Cyperacé-mire where they are so dwar-
fish and prostrate as to be of little significance. I have referred to
the whole of the shrub-mire as a single association and named it:
Vacciniétum uliginosi
The association is closely related to sociation 13: Eriophorum
angustifolium — Vaccinium uliginosum — Betula nana since the
environment is often similar. The Vaccinium association often
occurs in damp areas which approximate the wetness of flói, at
least in depressions, but here the surface is usually mound-pattemed
and sometimes the mounds are fairly coarse for a mire.
The slope is often insignificant, but sufficient to keep the ground-
water flowing. Peat formation is often insignificant. This seems
to be a fairly stable vegetation type, as most associations which grow
in damp areas. It is to some degree affected by intensive grazing,
and mowing greatly hampers its distribution in mires. The shrub-
mire as a whole corresponds to the Norwegian rismyr (Nordhagen
1943 p. 533) although it does not contain the same sociations, since
many of the most common rismyr species do not occur in this
country, such as: Andromeda, Rubus Chamaemorus, Eriophorum
vaginatum, Ledum palustre et alia. Oxycoccus is rare here, but
where I have encountered it the occurrences have always been in
a shrub-mire, especially among V. uliginosum and B. nana. I am
certain, therefore, that the Icelandic shrub-mire could be classified
as Oxycocco-Empetrion hermafroditi (Nordhagen 1943 p. 534).
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