Rit (Vísindafélag Íslendinga) - 01.06.1975, Síða 138

sunk. An examination of the C. Lyngbyei sociation as a whole re-
veals that it has an unusually small numher of species. In 19 ana-
lyses Calamagrostis neglecta is the only species to occur; in 15 of
them it may therefore be regarded as constant, hut only 8 species
occur in more than 5 analyses. Comarum palustre and Caltha
palustris occur 8 times and those areas should perhaps he disting-
uished as separate sociations. Furthermore, it should he noted that
Menyanthes trifoliata which occurs on two locations is so ahundant
there that this might be regarded as a separate sociation. I have
not done this, however, since I was unahle to detect any difference
in topography or environment.
Only E group occurs in the C. Lyngbyei sociation. The only A
species encountered there is Polygonum viviparum which is rare,
however, but this shows that it can thrive in practically any vege-
tation type. Shrub-plants are completely absent, but the Chama-
ephytes Cerastium cæspitosum and Sagina procumbens only oc-
curred to a very small extent at Hvanneyri. Chamaephytes are,
however, ahsent from this sociation.
79. C. Lyngbyei — C. nigra sociation
(Tab. XVm A-B 1-8)
This sociation is in fact closely related to 78, hut there are vari-
ous differences. C. Lyngbyei remains dominant in physiognomy,
but here C. nigra is an additional dominant which often nearly
equals C. Lyngbyei in covering. Eriophorum angustifolium and
Carex chordorrhiza occur to some extent, but are insignificant in
physiognomy and covering. Menyanthes trifoliata and Equisetum
palustre are much more abundant here. Most of the species, how-
ever, are the same as in 78 but the species are here somewhat more
nmnerous, for this sociation is almost as rich in species as the mire
sociations. This sociation generally occurs in drier spots than so-
ciation 78, and the flæðimýri is by no means as typical here. It
may he an older formation, and therefore less directly affected
by river flooding. It is conceivable that this sociation should be
combined with the C. Lyngbyei flói. Analyses 1-2 are from Eyja-
fjöll, helonging to the same series of analyses as the C. nigra —
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