Flóra: tímarit um íslenzka grasafræði - 01.03.1965, Side 124

ON THE VEGETATION OF THE CENTRAL HIGHLANDS
OF ICELAND
PART TWO
By Steindór Steindórsson, Akureyri College, Akureyri
The second part o[ this paper deals with the vegetation o£ the snowpatches,
which are defined here as plantformations in places where the snow-covering is
abnormally thick and lasts abnormally long, considerably longer than in the nearest
surroundings, even though the vegetation-period is not noticeably shortened.
The vegetation of the snowpatches in Iceland is divided into four groups. The
groups are arranged according to the thickness and duration of the snow-covering.
A. The Vaccinium patches. Here the snow-covering is the thinnest, and the
vegetation-period the longest within the whole formation. One association is de-
scribed, Vacciniétum Myrtilli, sociations 40—41. Although this association is closely
related to the heath-formation, it usually differs distinctly from it in the composi-
tion of species, in physiognomy and the fornr of landscape.
15. The Herb patches include two associations, Geranietum silvatici, soc. 42,
and Alchemilletum, soc. 43—45. As a rule the snow-covering is thicker in the herh
patches than in Vaccinietum, and the soil somewhat damper. Soc. 45 is an excep-
tion, as it grows in dry soil, and is often found in close connection with Vaccinie-
tum Myrtilli.
C. The Graminé patches. Only one association is descrihed, Nardetum strictae,
soc. 46—47. Closely related to it is soc. 48, the Carex Bigelowii-Agrostis canina soc.,
which more correctly would be listed as a special sociation.
D. The Salix herbacea patches. This alliance is the most typical and hy far the
most widely distributed formation of the snowpatches in Iceland. Only one assosia-
tion is described, Salicetum herbaceae, soc. 49—51. This association is closely rele-
tecl to the Anthelia association, of which no examples are referred in this paper.
E. Wet snow patches. Here two associations are described, Caricetum Lachena-
lii, soc. 52—53, and Phippsietum algidae, soc. 54. The former association occurs in
wet soil, either around springs or brooks or on the borders of marshes. The latter
is especially found near snowdrifts which are still melting late in summer.
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