The Botany of Iceland - 01.12.1945, Page 130

472
STEINDÓR STEINDÖRSSON
H umlum (1936, pp. 38-39) mentions a sowewhat similar vegeta-
tion. The only foreign descriptions which have been available to me for
comparison are that of F æ g r i from Jostedalsbræ and that of P o r-
s i 1 d from Disko. I have already pointed out the relationship with one
of the sociations mentioned by F æ g r i, but otherwise it would seem
that the development of vegetations is somewhat different here and
in Norway. Almost the same result is arrived at, I think, by a com-
parison with P o r s i 1 d’s description (1902, pp. 106-111), which shows
a quite different type of vegetation than that found on the moraine
dealt with here.
Although my observations from Kringilsárrani are few in number,
they show fairly distinctly how thc vegetation behaves in its initial state
on this moraine. We may say that the whole vegetation of the ground
moraine is still at an initial stage. The southernmost part of the moraine,
nearest the glacier, whence analyses 1-3 are derived, has not yet pas-
sed the “unstable years” (Fægri 1933, p. 110), i. e. the external
alterations of the moraine are still so great that they prevent the in-
vasion of the vegetation. Still this instability is less than might be
expected in view of the age of the moraine, the moraine being com-
paratively level.
What might seem peculiar in the colonisation by the plants of this
barren field is that the phanerogams apparently come before the cryp-
togams. It is true that my investigations are not quite satisfactory in
this respect, but this much may be established from them that in the
first pioneer stage in which analysis 1 was made, neither mosses nor
lichens were found, and apart from the aforementioned Philonotis
cushions the cryptogamous vegetation is very poor throughout the
moraine; it is far surpassed by the phanerogams both in regard to
degree of covering and to frequency. L ii d i seems to have come to a
similar result in the Alps, saying (1921, p. 225) : “Die Erstbesiedlung
erfolgt durch die besiedlungtiichtigsten Gefásspflanzen der Umgebung”.
The first pioneer species on the Kringilsárrani moraine are Catabrosa
algida, Draba rupestris, and Arabis alpina. In areas nearby, in which
these species were found, they were of a much lower growth and more
poorly developed than on the moraine. Thus in no other place did I
observe the phenomenon that Draba and Arabis had two flowering
periods in the same summcr. When I visited this locality in the middle
of August I found the two species with well developed stems with nearly
fully mature fruits from the first flowering; but at the same time new
stems whose first flowers had just come out were developing from the
rosette.