Rit (Vísindafélag Íslendinga) - 01.06.1975, Side 81

G. is everywhere the prime life-form. H percentage is consider-
ably reduced, whereas Ch percentage becomes substantial.
Although this sociation usually occurs in rather small patches
I have found it at Hlíð in Vatnsnes, where it was the main socia-
tion in an extensive mýri area. The terrain was mound patterned
and C. nigra was dominant everywhere on the mounds, but C.
rariflora in the hollows. Other prime species there were: E. angusti-
folimn, Carex rostrata, C. Halleri, C. vaginata, Polygonum vivi-
parum, Comarum palustre, Sahx glauca, Vaccinium uliginosmn,
Menyanthes trifoliata.
Where this sociation occmrs the terrain is medium wet with
some slope and the surface is most often patterned with low, flat
öiounds or flat.
Analysis 1 is from Múlakot in Fljótshlíð, taken at approx. 200
metres above sea level. The terrain is patterned with fine mounds,
and moss occurs on the mounds. I could not determine whether
the sociation is widely distributed there. Analysis 2 is from Vind-
hæli at Skagaströnd. The area is rather dry and the surface is
almost totally flat. C. nigra covers more than at the other loca-
tions, but otherwise the covering of both character species is about
oqual. Analyses 3-6 are all from Melrakkaslétta, where this socia-
tion occurs almost exclusively in a belt along hills, where they slope
towards the flói areas. Analysis 7 is from Skálanes in Vopna-
fjörður, where the sociation is widely distributed.
40. C. nigra — Menyanthes trifoliata sociation
(Tab. IX A-B 8)
The only analysis presented is from Orrastaðir in Húnavatns-
sýsla, where the Sociation grew in an extensive area, but disap-
peared in many places to merge with the preceeding sociation,
which is also widely distributed there. Viewed at a glance these
two sociations seem to be closely related, so that one might per-
tiaps be tempted to believe that it is the same sociation. Carex
rariflora e.g. is a dominant species in both, but in sociation 40 some
species appear which either are absent or are rarely seen in 39.
Apart from the character species M. trifohata, Carex chordorrhiza
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