The Botany of Iceland - 01.12.1930, Page 111

STUDIES ON THE VEGETATION OF ICELAND
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vegetation, and the Philonotis dý), rock pools and Grimmia heath.
Since the Grimmia heath does not occur in North Iceland, this type
may be left out of consideration, and of the remainder only the
injrri and the rocky pools are identical. Judging from the description,
H. J ónsson’s fell-field comprises Stefánsson’s melar, mo, and
snow-patch, gravelly flats and screes corresponding to melar and mo,
while the Anthelia crust and the Salix herbacea and Sibbaldia ve-
getation must be regarded as snow patch vegetations. Thus for the
highlands we get the following vegetation scheme which, in its main
lines, is the same as on Lýngdalsheiði, viz. 1) melar (and, in addition,
for South and East Iceland, Grimmia heath), 2) mo, 3) mýri (in-
cluding dý), and snow-patch (including the Salix herbacea and Sib-
baldia vegetation and the Anthelia crust). In the following each
of these types will be dealt with in inore detail.
As previously mentioned, the investigations to be described in
tbe following were carried out on Arnarvatnsheiði. The latter forms
part of the large plateau north-west of Langjökull wliicli divides the
Húna FIói area of valleys in the north from the Borgarfjörður area
of valleys to the south. The surface of the plateau consists of de-
posits of the glacial period and appears as a landscape with count-
less downs, depressions, and lakes.
Of more conspicuous types of vegetation we find: melar, Betula
nana mo, the knolly mo, jaðar, mýri and flói, and geiri. The melar
vegetation attains development at the top and on the ridges ot
the downs, occasionally some distance down the slopes. The Betula
nana mo (or the level mo) occurs on large ílats at high levels among
tracts of melar. The mo (the knolly mo) occurs in small hollows
in the Betula nana mo, along the slopes of the downs, in large flat
depressions at liigh levels, and in the margins of the snow patches.
Jaðar occurs especially in the depressions between the downs and
on the borders of the mýrar, while the mýri vegetation occurs
in the larger and deeper depressions and around the lakes. The
moister parts of the mýri are occupied by the flói. Tlie geiri
vegetation attains its finest development in large shovel-formed
depressions in the hills, most frequently, though not so typically,
developed along the slopes of the hills.
As elsewhere in Iceland, the melar and geiri vegetations are
dependent respectively on a slight and a deep snow-covering. The