The Botany of Iceland - 01.12.1945, Side 43

THE VEGETATION OF CENTRAL ICELAND
385
adjoining the inhabited parts. As mentioned above, the largest areas
of flói investigated are found along rivers. Otherwise the flói formation
mainly occupies small tracts of land surrounded by other formations.
This can be most distinctly observed in the “flá”, which is a kind of
formation mosaic. This is in full accordance with the conditions de-
scribed by W a r m i n g and Ostenfeld from Greenland. Thus it
is one of the characters of the highland vegetation that large continuous
areas of flói are of rare occurrence, and this formation is only found in
depressions enclosed by mýri associations or shrub heath.
(Tables I-III A-B)
The tables show the composition of the flói vegetation in the high-
land of Iceland. It is always poor in species, the analyses showing 2-10
species. The two species Eriophorum polystachyum and Calamagrostis
neglecta are nearly always present and often dominant. Other fairly
constant species are Carex rariflora, Eriophorum Scheuchzeri, and
Salix glauca. These species, with the exception of Salix glauca, are as
a rule found in the lowland flói also, where Calamagrostis is never
among the dominants (cf. Molholm Hansen 1930, p. 70, and
Steindórsson 1936, p. 442). Of the species which are very com-
mon in the lowland flói Carex saxatilis is absent in the highland flói.
The most important associations of the highland flói are the following:
1. Eriophorum polystachyum—Calamagrostis neglecla-Ass.
(Tab. I. A-B, 1-4).
Analyses 1-2 were made in Hvannalindir. The surface is entirely
level, but the soil is sandy. The association is found in narrow stripes
among Juncus balticus and Salix glauca associations. The two character
species occur in equal numbers; I assume, however, that Calamagrostis
has a higher degree of covering, whereas Eriophorum is more pro-
minent physiognomically. These analyses represent a type of flói which
is a transitional form between flói and Calamagrostis-mýri. Analysis 3
is from Kýlingar and analysis 4 from Jökuldalir, both were taken at
the margins of the flói formation, where it borders on sandy areas and
is comparatively dry during a great part of the year, but where in-
undation often takes place. In these two localities Eriophorum is ab-
solutely dominant both physiognomically and as regards degree of
covering. The moss vegetation is inconsiderable. This association rarely
occurs.