Rit (Vísindafélag Íslendinga) - 01.06.1975, Page 61

dence, although they reach a high frequency count. C. nigra, C.
rariflora, Equisetum palustre and Vaccinium uhginosum all have
a high frequency in some analyses and Vaccinium uliginosmn is
constant in all of them, and it would perhaps have been proper to
ídentify the sociation accordingly. On the other hand it is pro-
strate everywhere and disappears among the character species. The
surface is pattemed hy low, flat mounds except for VIx 13, which
is from Krýsuvík, taken in the mountain above the hot spring.
Sphagnum occurs on all locations. In general this appears to he a
transitional stage leading to a Scirpus mýri.
30. C. rostrata — C. nigra sociation
(Tab. VIA-B 9-11)
This is the most widely distributed sociation of the C. rostrata
flói, although this is the only analysis. Throughout the country,
where a C. rostrata flói occurs, this sociation is found, and in most
mstances it has the widest distribution. It often phases into a Carex
nigra mýri with a vague borderline between. The sociation is quite
rich in species, but in composition it does not differ much from
other sociations of the C. rostrata flói, except for the C. nigra,
which becomes dominant in frequency coimt and in covering every-
where, which is not tme of other flói sociations. It often covers as
much or more than C. rostrata. On the other hand ahnost all
character species of the C. rostrata flói appear here to some extent,
which also applies to their accompanying species. The C. rostrata
flói is probably not to be fully divided into sociations except on the
basis of mosses. Of species which occur here, but not in the other
sociations Drosera rotundifolia may be mentioned. It was common
at the observation site, but otherwise it is rare in Iceland, Em-
petrum and C. saxatilis were also present. It occurs in only one
analysis of the C. rostrata flói, but nevertheless a pure C. rostrata
-— C. saxatilis sociation does occur in many places. It never covers
more than small areas, preferably near ponds. Then hardly any
other species occur there except perhaps for a trace of C. rariflora,
and. it is difficult to determine which species is more predominant.
Vegetation is always continuous with httle moss. Since no more ana-
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