Rit (Vísindafélag Íslendinga) - 01.06.1975, Page 74

become prevalent without C. nigra disappearing altogether. Many
traces thereof may be seen near drainage ditches. Although the
mýri becomes saturated considerably, no important change is to be
discerned in its vegetation, as long as the slope is sufficient to pre-
vent ground water from stagnating. The main concurrent change
is that species become fewer, moss diminishes and C. nigra becomes
more sparse, taller and more noticeable in the vegetative cover.
The C. nigra mýri has throughout the coimtry succumbed to
impressive changes due to harvesting, mowing and grazing. I ex-
pect that extremely few of those öbservations which have been
made of it in the lowland emanate from terrain, which has evaded
this influence, and many were certainly taken on meadows. I can
not see that harvesting or grazing has exerted significant influence
on rhe main species. On the other hand various accompanying spe-
cies more often emerge in harvested mýri tracts, but others, parti-
cularly shrubs diminish or disappear. Moss decreases generally
where meadows are consistently harvested.
There appears to be no doubt that the C. nigra is closely related
to Smástarr — Grasstarrmyrernes forbunn, Caricion canescentis —
Goodenoughii in Sikilsdalen (Nordhagen 1943, pp. 482 ff.), al-
though C. canescens is very frequently absent from it. Further-
more, sundry species of the Scandinavian forbunn are constant
species in the C. nigra mýri, and its appearance is similar in many
ways.
I have grouped several sociations together in this association,
which I refer to as Caricétum nigrae, but the same may be applied
here as to the flói, i.e. that, since the mosses are not considered,
this definition might be affected by their subsequent examination.
Tliis is more applicable in the mýri than in the flói, because the
moss species are more numerous and therefore probably more
varied.
If we examine the position of the main species of mýri with
respect to acidity, it runs as follows:
Carex nigra: eutroph-mesotrophic
Eriophorum angustifolium: indifferent
Carex rariflora: indifferent
C. chordorrhiza: indifferent
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