The Botany of Iceland - 01.12.1945, Blaðsíða 142

484
STEINDÓR STEINDORSSON
analyses of the vegetation were made according to it. In Table XXV,
in which the results of all the analyses are given, analyses from the
same locality are found in columns with the same number through
all the belts.
(Table XXV. A-B).
Series i (Tab. XXV, i) is from Fagridalur, from a flá of small
extent. It has developed on a large mýri flat in the lower part of the
valley. The flá is found in the middle of the flat. Its rústs are relatively
low and of small extent, only a small number of them attain a height
of one metre. Their tops are domed and so damp that there is no
removal of soil by the wind although the vegetation is open. The dif-
ference in vegetation of the various zones is less than is usually the
case, especially between zones 2 and 3, which is the rule when the
rústs are as low as here. I have mentioned above the characteristic
knolly ridges which occur precisely in Fagridalur; they are found
where the bottom of the valley is somewhat inclined, whereas the flá
occurs in places where the surface is entirely level.
Series 2 and 3 (Tab. XXV, 2-3, Figs. 16, 18) are from Háumýrar,
a fairly extensive mýri area east of Fagridalur. A brook abounding in
water flows through this mýri area; along the brook and in the whole
outer part of the oasis there occurs Salix heath, but the greater part of
this is made up of a flá. Near the margins of the flá the rústs are
low, and sometimes their tops are covered by a jaðar or heath vegeta-
tion, while the depressions are clad with Eriophorum Scheuchzeri and
Calamagrostis. In the middle of the flá, however, there are fairly
deep pools and large rústs up to 2.5-3 m high. The tops of these are
poor in vegetation or are covered by a scattered flag vegetation, and
the wind erosion is very distinct here. Degeneration slopes devoid of
vegetation are found near the banks of several pools. Furthermore,
rústs may bc met with on which vegetation belt 3 is entirely lacking,
and the whole edge of which is clad with a scattered flag vegetation
(Fig. 16 B-C). Series 2 (Fig. 18) is from the margin of this flá, wherc
the soil is rather sandy. Eriophorum polystachyum hardly occurs in
belt 1, but has been replaced by E. Scheuchzeri. Somewhat exceptional
is the Calamagrostis—Carex rw/ma-association, which is distributed in
belt 2 here, but otherwise I did not meet with C. rujina in the flá
except in Hvannalindir (Fig. 17, 3). Between the growths of Eriopho-
rum and C. rufina there is a pure Calamagrostis growth (see Fig.
18, 3). The rúst is low, and Calamagrostis is exceptionally abundant