Rit (Vísindafélag Íslendinga) - 01.06.1975, Page 18

Mire Vegetation
As has already been stated the mire has been defined as an area
of land where hygrophile plants grow, so that its entire vegetation
is all of a hygrophile character. This also applies where it is defined
on a topographic hasis, since tiie botanical and the topographic
definitions largely coincide. The vegetation of Icelandic mire areas
is generally homogeneous, although it is subject to changes depend-
ing on the lie of the mire, moisture content and other local condi-
tions.
A continuous vegetative cover is a common characteristic of all
mire vegetation. There are two vegetative layers. The bottom layer
consists primarily of moss species. A common characteristic of Ice-
landic mire tracts is the scarcity of Sphagnum, and nowhere have
I foimd it in such abundance that it forms a continuous vegetative
cover. In my research I have not had the opportunity to treat moss
to any extent, but individual observations and other research indi-
cate that the following species are most common. Hypnum, several
species, also species of the family branches of Catoscopium, Philo-
notis, Cinclidium and Mnium. In the North and East of Iceland
Thuidium lanatum is one of the most common moss species. Hes-
selbo’s work is relied on in this context. In some areas there are
traces of Lichena, but nowhere so as to be conspicuous. As the
mire becomes more moist the bottom layer is more open. Moss
species become more scarce and sparse. In the wettest flói areas
the moss disappears almost altogether, but between the phanero-
gams the bare soil either protrudes or it is covered with slime of
algae. A few phanerogams are found in the bottom layer, e.g. Utri-
cularia minor, Oxycoccus microcarpus and a select few other types,
but they are rare and hardly noticeable in the vegetation cover
where they are found. The phanerogams of the mire are mainly
Cyperacéae. A very few species predominate there, and these are
found virtually everywhere in mire tracts and characterize their
particular sociations. The most common species are Eriophormn
angustifolium and Carex nigra or in its place C. Bigelowii in high-
land mire tracts. Other common species are C. rariflora, C. chor-
dorrhiza, C. saxatilis and C. rostrata. None of these species occorn:
outside mýri tracts except C. Bigelowii, which is most frequently
18