The Botany of Iceland - 01.12.1930, Qupperneq 65

STUDIES ON THE VEGETATION OF ICELAND
55
The (íeiri Vegetation. Figs. 9—10 and table 13 A—B.
Where for orographic reasons the snow forrns a covering early
in the autumn, remains on the ground in a more or less deep layer
throughout the winter, and does not melt until late spring, a special
type of vegetation is developed which may be called by llie Icelandic
name Geiri (the vegelation of the snow-patclies).
It is a characteristic of the snow patch that the underlying soil
is never knolly as is the case with the surrounding ino, and further
that the vegetation is fairly luxuriant. These two circumstances in
conjunction make the snow patch very conspicous even from a long
way oif (see íigs. 9—10).
In table 13 A the circling results for the geiri vegetation of Lýng-
dalsheiði have been tabulated; this vegetation is only present in the
middle and upper tracts of the heath, from c. 200 m above sea level
nnd upwards. It was most characteristic at the upper levels.
The geiri vegetation comprises several formations which can
he distinguished with regard to their environment by differences in
the duration and depth of the snow-covering, the height above the
sea, and illumination. As regards the general composition of the
vegetation the following holds good. Vaccinium uliginosum is abso-
lutely the dominant plant, in conjunetion witli Empetrum nigrum
and Deschampsia flexuosa it forms the bulk of the dense luxuriant
carpet of vegetation. Species like Salix herbacea, Calluna vulgaris,
Agrostis canina, Festuca rubra, Anthoxanthum odoratum, Luzula
multiflora, Carex rigida, Galium boreale, G. Normanni, Cardamine
pratensis, and Taraxacum offlcinate also abound. Rubus saxalilis,
Geranium silvaticum, and Vaccinium mgrtilliis are characteristic of the
geiri on Lýngdalsheiði. None of these species has been met with
in any other type of vegetation. Some typical mo plants occur dis-
persed throughout the vegetation, in greatest quantity in the least
typical snow patclies, or in tlie margin of Ihe larger ones.
In small depressions in the mo, where the snow-covering gives
rise to another vegetation than in the mo itself, this vegetation is
fairly uniform throughout the depression. In deeper depressions a
diflerence between the vegetation at the bottom and up the sides
be perceived. In table 13 A, 4—5 show respectively the typical
geiri vegetation and the vegetation on the sunny northern side of
the snow patch. Here the density of species is somewhat greater,
15.5 as against 13.6, owing lo a contingent of mo plants.
In still deeper snow patches one may dislinguish between a