Rit (Vísindafélag Íslendinga) - 01.06.1975, Page 85

cate. In many places it is not easily distinguished from the Equis-
etum-mire. It is decisive in this matter which species is more domi-
nant, E. palustre or C. nigra, hut both these sociations thrive in
similar conditions. This is the most fertile and useful mire-sociation,
together with Equisetum palustre — C. nigra sociation 63. The
species are numerous and the mire as a whole is lush and grassy.
It was therefore used for haymaking all over the country while
mires were still used for such purposes. C. nigra is dominant every-
where in this sociation, hoth in physiognomy and covering, hut
closely followed by E. palustre which is almost as frequent. The
mire invariably slopes, often steeply, and the surface is knolly.
There is a slight difference in vegetation between knolls and de-
pressions. E. palustre is characteristic for the knolls and they also
tend to be mossier. The flói species, on the other hand, are mostly
found in the depressions. Constant species together with the char-
acter species are Polygonum viviparum, which occur with practi-
cally the same frequency as the character species, Festuca rubra,
Carex rariflora and Thalictrum alpinum. The following species
are common: Carex capillaris, Parnassia palustris, Pinguicula vul-
garis, Calamagrostis neglecta, which is, however, far less common
here than in many other mire sociations, Rhinanthus minor, Festuca
vivipara, Salix glauca, Vaccinium uliginosum, Comarum palustre,
Eriophorum angustifolium, which is very rare, however, and al-
Ways stunted and sterile, and Galium pmnilum.
The vegetation indicates that the sociation is eutroph-mesotrophic,
which is in fact a general characteristic of the C. nigra mire.
The biological spectrum shows a large numher of species, up to
40 species in a single analysis which is the maximum that has been
found in Icelandic mire vegetation. The majority always fall into
the E-group, although proportions vary somewhat. There is con-
siderable fluctuation in the H and G percentage depending on where
the observation was made, but the G percentage is usually higher,
although the H percentage is high for mires. In a small number
°f analyses the Ch percentage is notable, but they do not occur
where the sociation is at its purest. HH occurs at times and Th is
also more prominent than in most other mire sociations. All this
seems to indicate that the environment is favourable to a large
variety of plants.
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