The Botany of Iceland - 01.12.1945, Page 21

THE VEGETATION OF CENTRAL ICELAND
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most exclusively restricted to the small oases found near springs and
rivers, while otherwise vast stretches have been devastated by blown
sand, especially in the westernmost part of the region near Jökulsá á
Fjöllum. This blown sand, which apparently originates from the lava
fields of Ódáðahraun, loses its power farther eastward, where large
continuous areas covered with vegetation occur. In the northern part
of the area large accumulations of pumice stone are found everywhere,
remnants from the great eruption of Dyngjufjöll in 1875. This eruption
is no doubt largely responsible for the destruction of the vegetation in
this region. Distinct traces are still visible, showing how pumice stone
and volcanic ashes have destroyed the vegetation and thus paved the
way for the destructive influence of the wind erosion. The greater part
of the region lies between 500 and 600 m above sea-level, but rises
evenly towards the south. My stations and at the same time the largest
oases are as follows:
1. Arnardalur is a low depression situated c. 30 km south
of the farm Möðrudalur. A small stream, whose rather abund-
antly flowing sources are found in the valley, runs through it. The
heights around the valley slope evenly, except Arnardalstindar, wlrich
rise rather steeply on the western side of the valley. Nearest the stream
the vegetation consists of stretches of mýri dominated by Eriophorum
Scheuchzeri and Calamagrostis neglecta. This part of the valley bottom
is perfectly level and appears to be formed by a lake filled up by the
stream. At a greater distance from the stream Eriophorum polystachyum
flói and an inconsiderable “flá” formation are met with. In places
where the valley bottom is more elevated we find Scdix heath, but be-
tween this and the moist bottom there is a Juncus balticus belt. Dune
formations with patches of Elymus occur along the mountain sides.
The slopes themselves are covered with a poor fell-field vegetation or
are entirely barren.
2. Þ o r 1 á k s 1 i n d i r. West of Arnardalur low ridges alternate
with level sandy stretches as far as K r e p p a, the tributary of
Jökulsá. The greater part of this area is a blown-sand desert with oc-
casional small Elymus dunes. In my diary I find the following note on
this stretch: The ridge west of Arnardalur and the sandy areas farther
westward may be said to be entirely devoid of vegetation if we disregard
the small Elymus dunes. In places, where small stones or the like give
some shelter against the wind and the loose sand, some few plant
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