Rit (Vísindafélag Íslendinga) - 01.06.1975, Blaðsíða 27

banks. Supraaquatic mire is in my estimation non-existent in Ice-
land, one of several reasons being tliat Spliagnum is mostly in-
S1gnificant in Icelandic mire vegetation.
V egetation
As stated earlier Cyperacea is dominant in flói vegetation. The
vegetative cover is mostly continuous, except where it is so moist
that pools and ponds develop in spring or during periods of rain.
When they dry out again, they often leave small bare spots, or at
least rot patches between sparse blades of grass. These bald patches
are frequently more or less covered with slime of algae. At times
these pond sites are completely covered with Subularia aquatica,
Ranunculus hyperboreus, or R. reptans. The moss layer is always
little developed in the flói, and where moisture content is highest,
the moss disappears almost or altogether. Hesselbo states: “Hyp-
num scorpioides and H. giganteum are the most frequent species
which occur everywhere in pools and channels. Hypnum exan-
nulatum, H. revolvens var. Cocconi and Acrocladium cuspidatum
are also frequent. In many places in East-Iceland Cinclidium
stygium was found abundantly in Flóar, while Hypnum cordi-
folium and H. fluitans were found in a few places only.” (Hes-
selbo 1918, pp. 556-7).
One of the main characteristics of the flói is the paucity of species
and their sparse distribution. No Icelandic soil is as poor in species.
The sociations of the flói are not sharply defined internally nor
does the flói contrast markedly with the mýri which is in part a
result of the changing level of the ground water from year to year
according to precipitation. Yet, the wettest parts of the flói may be
considered to have stable plant communities. The distinction be-
tween flói and mýri is by no means clear, neither from a topo-
graphical nor botanical point of view, as is borne out by the des-
criptions of individual sociations. Thus some of the flói sociations
are related to those of the mýri and vice versa, and then topograp-
hical difference is employed to determine whether they should be
classified with flói or mýri. The distinction between these main
divisions of Icelandic mires is founded on the moisture content of
the soil, as has already been stated, and on the basis of the gradient
°f íhe surface. But the moisture content must in part be deter-
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