Rit (Vísindafélag Íslendinga) - 01.06.1975, Page 54

21. C. Lyngbyei — C. limosa sociatiou
(Tab. V A-B 11-12 and Tab. VX 6-8)
All the observations are from Rangárvallasýsla, and I have not
found this sociation elsewhere, although I expect that it occurs in
other parts, since hoth species favour tracts rich in bog iron. But
it should be noted that C. limosa is rare in some parts of the coun-
try, e.g. it hardly occurs at all in highland areas. C. Lyngbyei is
dominant everywhere both in physiognomy and covering, but
Menyanthes trifoliata is conspicuous and Equisettun palustre occurs
to some extent, but it is otherwise rare in flói sociations.
Analysis Vx8 is made in the area with an abundance of shallow
ponds altogether covered with Scirpus palustris and Equisetum
fluviatile, between which this sociation grows. This area appears
to he drying out, which e.g. may be deduced from the fact that
C. limosa disappears in patches and phases into an almost pure
C. Lyngbyei sociation, otherwise all the observations are made on
very wet ground where bog iron clay occurs in abundance.
22. C. Lvngbvei — Calamagrostis neglecta sociation
(Tab. VA-B 14-21)
This sociation was examined at several locations in the high-
land but I have not noticed it in lowland areas, although it con-
ceivably occurs there. It is in close connection with the flæðimýri,
and it is doubtful whether it should more appropriately be clas-
sified with the flói or the flæðimýri, and in some parts there is an
intermediate stage in development from flæðimýri to flói. C. Lyng-
byei dominates both in physiognomy and covering despite the high
frequency of Calamagrostis. The prime accompanying species are
C. rariflora, Salix glauca and Comarum palustre, so that there is
a visible relationship with the sociations 18—20.
As stated above this sociation has some flæðimýri characteristics,
which is best revealed by examining the topography where analyses
15 and 16 were made, both of which are from the extensive flói
and mýri areas in Hvitárnes at Kjölur (420 metres above sea level).
There we find a vast area, measuring many square kilometres,
which has been formed when glacial streams have filled up a lake.
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