Rit (Vísindafélag Íslendinga) - 01.06.1975, Page 70

a few indications as to its distribution. The mýri has been one of
the most valuable of mire divisions for haymaking purposes, and
in later years it has been cultivated on a wide scale, since the slope
facilitates their drainage and drying out. In the highland the mýri
is often replaced by flói tracts and consequently it is not as widely
distributed there in proportion to area as in the lowland. The dif-
ference between flói and mýri is less there than in the lowland
because the highland mýri slopes less. Hence there is little differ-
ence between it and the flói, and many of the same species occur
in highland flói and mýri, since competition for survival is less
intense there than in the lowland on account of the paucity of
species. The sociations of the highland mýri are generally not clear-
ly defined, and I have some reason to believe that most of the high-
land sociations are a kind of transitional form either from a damper
to a drier stage or the reverse. The mýri sociations in lowland
areas may be regarded as fairly stable, whereas the highland so-
ciations are generally unstable and they often come closer to being
properly described as fragments and variants of the actual socia-
tions, which occur in related formations or under similar circum-
stances in the lowland. This is largely due to local topography
where mýri areas occur in the highland. In the lowland they may
cover extensive areas, which may, to be sure, be disrupted by indi-
vidual hills or ridges, and patches of flói may occur in lowlying
mýri areas, but the highland mýri tracts most often occur in the
shape of belts of varying width around flói areas or on their ex-
tremes, or they occur along rivulet beds. It often happens in the
highland that in hollows the flói covers the bottom, but around it
a belt of mýri extends, which merges into a heath without clear
borders, since two of the most common species of the highland
mýri and heaths are the same, Carex Bigelowii and Sahx glauca.
In the lowland on the other hand the borders between mýri and
dry ground are always clear, but often a belt is inserted, which
H. Molholm Hansen referred to by the name jaSar (fringe), which
has since been retained. The jaðar can often be an intermediate
stage between two adjacent sociations, but at times it contains
fully independent sociations (Juncus balticus). The jaðar will be
discussed at greater length later, but it actually belongs either among
mýri or dry ground.
70