Rit (Vísindafélag Íslendinga) - 01.06.1975, Page 142

country its deposit is not pure sand, but mixed with hmnus ma-
terials. The delta itself is very damp and hard to traverse. The
dampest patches are almost exclusively covered with E. Scheuchzeri,
but where the soil is firmer there is a continuous vegetation cover
of this sociation. E. Scheuchzeri is dominant in physiognomy, but
A. stolonifera and Juncus alpinus are similar in covering. Triglo-
chin palustris is also conspicuous. It is noteworthy that Catabrosa
aquatica seems to be the first pioneer species there and has taken
root in mud patches close to the surface, before E. Scheuchzeri
gains a firm footing. E. angustifolium is not conspicuous in the
sociation, but increases at some distance from the lake where the
ground becomes somewhat drier, and gradually phases into an
Eriophorum angustifolium flói, in which case E. Scheuchzeri dis-
appears altogether.
Those E. Scheuchzeri sociations which have been described here
are all from the highland, but they also occur in lowland areas,
particularly sociation 83. This was the case on the border of Safa-
mýri. Sands and mudflats formed there in the Djúpós prior to the
construction of a dike. While the sand was damp enough fairly
large expanses of E. Scheuchzeri occurred there, as well as Agrostis
stolonifera, Juncus alpinus, Juncus bufonius and Calamagrostis neg-
lecta. Where the ground was dry it changed into grassfield or jaðar
(border) with Equisetum palustre or Juncus balticus as dominant
species together with various gramineous plants.
84.-85. Catabrosa aquatica — Ranunculus hyperboreus sociation
(Tab. XIX 6-7)
C. aquatica — R. hyperboreus — Eriophorum Scheuchzeri
sociation (Tah XIX A-B 8)
Those sociations were only analysed at Hvítárvatn, but they also
occurred in Kaldidalur, cf. sociation 83. This is possibly only one
sociation, but I have distinguished between them, because they
formed two strips along the shores of the lake; 84 next to the lake,
but 85 farther away. Those analyses, together with analysis XIX. 9
show how the vegetation cover is formed in the vicinity of the lake.
142