The Botany of Iceland - 01.12.1945, Blaðsíða 95

THE VEGETATION OF CENTRAL ICELAND
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found on “freshly formed soil”, which in many cases agrees well with
the soil of the alpine shrub heath. Molholm Hansen describes
no formation from Arnarvatnsheiði which might be referred to the
shrub heath, but describes some types of mó which do not differ notice-
ably from the lowland mó. Andersen & Falk (1935, pp. 410-
411) mention a “willow community” from Hvannalindir which, ac-
cording to their map of this oasis, is the shrub heath described here.
It is true that these authors do not mention Salix glauca as a dominant
species in this “willow community”, though it is a very conspicuous
dominant and far more widely distributed than S. lanata. Finally,
Humlum (1936, p. 63 ff) mentions willow heath from North and
Northeast Iceland in entirely the same meaning as is done here.
I have come across no description of the shrubby heath by other
authors than those mentioned here who have written about the vegeta-
tion of Iceland, but I shall briefly mention what I have found concern-
ing closely related formations in the other northem countries. As far
as I understand from the available literature, this formation is not
found either in Greenland or in Scandinavia, but probably several very
closely related communities occur. The Salix scrub described by
W a r m i n g and other authors from Greenland is much richer in
species than the shrubby heath, and the character species Salix glauca
is more vigorously developed, since in the Greenland formation it forms
an actual scrub. The same is the case with the Salix scrub recorded
from Scandinavia by several authors. More closely allied to the shrub
heath are the heath series described by B ö c h e r, notably the Saílix—
Empetrum-associa.úon. Otherwise the “Zwergstrauchgesellschaften” men-
tioned byNordhagen, the “arctische Haide” by P o h 1 e, p. 95, and
the ‘'Microsaliceta” by H u 11 are closely related to the shrub heath
or corresponding formations. The main difference from the shrub heath
in Iceland is that Salix glauca is nowhere so predominant as in Iceland,
and the ground vegetation is much less developed in the Icelandic
shrub heath than in the corresponding formations in the other north-
ern countries.
(Table XIII-XVI A-B).
The tables show which species are found in the shrub heath and
further the biological spectra of the formation. From these it will ap-
pear that the shrub heath is richer in species than the formations of
the mýri series, and that it has a greater species density. The arctic
species everywhere show a considerable majority in proportion to the