Rit (Vísindafélag Íslendinga) - 01.06.1975, Blaðsíða 73

this basis I have divided the mýri into four main divisions: Cype-
racé mýri, Equisetum mýri, shruh mýri and Graminé mýri.
The Cyperacé mýri is the most widely distributed and most
varied in vegetation. Within these divisions I have classified the
sociations into associations, which are 4 in the Cyperacé mýri, but
one in each of the others.
If the mýri as a whole is compared with associations abroad I
believe that it will in the main coincide with the godgrasmyr i
Sikilsdalen (Nordhagen, 1943, pp. 450—541).
a. Cyperacé mýri
a. 1. Carex nigra mýri — Caricétum nigrae
This association is the most widely distributed of all mire asso-
ciations in Iceland. Everywhere C. nigra characterizes the country
and lends the landscape a lovely green colour, which, to be sure,
acquires a slightly different hue, if many herbaceous plants grow
there. A significant number of C. nigra is always sterile. This plant
is usually 20-40 cm. high. The vegetation is always continuous
but not dense, so that the moss layer sticks out everywhere among
the blades of grass. The surface is most often mound pattemed.
Moss is generally more abundant on mounds than in hollows, but
the C. nigra grows purer in the hollows, and its accompanying
species are more abundant on the mounds, which particularly ap-
plies to the Graminéa, shrubs and Equisetum. Moisture content is
average, and indeed C. nigra does not appear to be significantly
vulnerable to changes in moisture content, as long as water does
not flood the soil, but it tolerates damming for a short period during
summer, if the terrain gets to dry out reasonably well afterwards,
as was mentioned in the description of the Eriophorum flói. The
grassroot of the C. nigra mýri is quite dense, and it is therefore
easily traversed. Peat formation is present everywhere in the low-
land and it is generally maximal where the mýri is wettest.
The C. nigra mýri seems to be a stable vegetative area, which
may be due to the fact that the main species have a fairly wide
amplitude with respect to moisture. However, it does not tolerate
any drying out to any extent whereupon it quickly changes into
grasslands or perhaps rather into a Graminé mýri, where Graminéa
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