The Botany of Iceland - 01.12.1945, Blaðsíða 77

THE VEGETATION OF CENTRAL ICELAND 419
(Tables X-XII, A-B).
Herbs are often very conspicuous in the snow-patch formation,
setting their mark on the physiognomy of the snow-patch; in other
cases it is dwarf shrubs, especially the various species of Vaccinium as
also Salix, which are the most prominent plants; in extreme snow-
patches such species as Catabrosa algida, Cerastium trigynum, and
Salix herbacea are the most frequent. On the whole this formation is
rich in species and also exhibits a fairly high density of species; this,
however, does not apply to the extreme snow-patches. The southern
species are fairly common, and in some few associations the E percentage
attains its maximum in the highland vegetation. H is generally the dom-
inant life-form, while Ch and G vary according to the associations.
Occasionally, however, the Ch percentage may exceed the H percentage.
This formation is recorded by several earlier authors under dif-
ferent names. The first botanist who described the small patches, rich
in species, which are especially found in depressions in the lower parts
of the mountain sides, was Stefánsson (1894, p. 191 ff.). In his
description of the vegetation of Vatnsdalsfjall he says (translated from
the Danish) : “The three last-mentioned species, Gnaphalium norvegi-
cum, G. supinum, and Sibbaldia procumbens, occurred here and there
in small depressions in such large numbers that they formed a con-
tinuous carpet” (1. c. p. 195). Jónsson often mentions the snow-
patch vegetation in his papers without defining it as a separate forma-
tion. It is mentioned as a special type within different formations, thus
the Vaccinium patches in the heather land and the Alchemilla vulgaris
community of the herb field recorded by him no doubt belong to the
snow-patches. From higher levels the same author records the dwarf
willow vegetation (1895, pp. 42-43), which is largely a typical snow-
patch vegetation and even occurs in snow-patches with a long-lasting
snow-covering. On Snæfellsnes he distinguishes between an Anthelia
crust and a Salix herbacea—Sibbaldia vegetation. The latter is stated by
him to grow in depressions; he gives a list of plants from such a de-
pression which contains typical snow-patch species. The vertical dis-
tribution of these communities, according to J ó n s s o n, is 300-790 m
above sea-level for the Anthelia crust, but 300-600 m above sea-level
for the Salix herbacea—Sibbaldia vegetation (1900, pp. 32-33). The
herb slope recorded by the same author both from Snæfellsnes and
southern Iceland is doubtless in part lowland snow-patches, and like-
wise the “blómlendi” mentioned by Jónsson, Stefánsson, and