The Botany of Iceland - 01.12.1945, Síða 129

THE VEGETATION OF CENTRAL ICELAND
471
Cerastium alpinum are conspicuous species and, where the soil is sandy,
Arenaria norvegica. Thus at the present stage of covering it is a gramin-
eous association; but it is, of course, impossible to decide which as-
sociation will be predominant when the whole moraine has been
covered by vegetation. The number of species is extremely high, and the
density of species is fairly great. The biological spectra show that the
arctic species are in the majority. The Ch percentage is relatively high.
H is the dominant life-form. G is sparsely represented in analysis 6,
but not on the moraine.
Analysis 4 was made near the middle of the moraine. There the
vegetation shows a considerable decline as compared with the localities
of the preceding analyses; the soil is colder than in those localities, and
a nucleus of ice is no doubt present in all the hills, only covered by a
rather thin layer of clay and gravel. Poa alpinat and Deschampsia alpina
are still dominants, while the other Gramineae have been much reduced
in number. A new species, Cerastium trigynum, has been added, while
other species have disappeared; however, there is no great difference
in the number of species, while the total of points has decreased
considerably. Still a number of southern species occur. In analyses
2 and 3 Deschampsia alpina and Poa alpina still dominate, but in
company with them there occur Catabrosa algida, Dra'ba rupestris, and
Cerastium trigynum. The only other species represented in these two
analyses is Arabis alpina. Only arctic species occur here, and the vegeta-
tion tufts are very few in number and scattered, so apparently the
moraine is devoid of vegetation. Analysis 1, which was made at a short
distance from the glacier’s edge, or near the limit of vegetation, shows
similar conditions, though Catabrosa, Draíba, and Arabis have become
dominant, while Poa and Deschampsia have been much reduced.
Cerastium, too, is less conspicuous than in analyses 2-3. No other
species except a single individual of Poa glauca was observed so near
the glacier. Hardly any mosses were found in the vegetation nearest
the glacier or on the moraine altogether. In the innermost part of the
moraine the soil is very wet, and the layer of soil covering the ice is
doubtless very thin. No doubt it is not many years since the first vegeta-
tion took root here.
As far as I know, the moraine vegetation in Iceland has never before
been treated in the literature. I assume, however, that part of the
vegetation described by Stefánsson (1902, p. 35) from Arnarfell
is precisely the vegetation found on old terminal moraines and might
thus be compared to the vegetation shown by analysis 7. Furthermore