The Botany of Iceland - 01.12.1945, Síða 66

408
STEINDÓR STEINDÓRSSON
When the soil has become so dry that Eriophorum disappears entirely,
we are confronted with the Calamagrostis jaðar. The boundary between
this and the mýri formation may conveniently be drawn where the
Eriophorum has almost or entirely disappeared. However, besides in
the formations mentioned here, Calamagrostis is found in other forma-
tions, also, both in the wettest flói associations, in the Eriophorum
polystachyum flói, and in the dry Sailix heath.
I have referred the jaðar to the mýri series on account of its close
relationship with the mýri formation and the many species they have
in common. It might, indeed, with just as good reasons be referred to
the next series, the meadow series, since this series forms a kind of
intermediate- link between the mýri series and the community of the
dry soil. Thus Nordhagen (1928) refers the Calamagrostis as-
sociation to the “moosarme Wiesen”. His description of a Calamagrostis
neglectaí meadow on the banks of the Nea river shows clearly that the
association depicted represents a very closely related, if not quite the
same, community as the Calamagrostis jaðar mentioned here. N o r d-
hagen says (1. c. p. 338): “Auf den feinkörnigeren Alluvionen des
Neaflusses bildet die CalamagroStis neglecta-Wiesen hier und dort
schöne giirtelförmige Bestánde . die im Friihling iiberflutet und
iibersandet werden... Als Bestandeselement traten hier Cala-
magrostis neglecta (1005), Equisetum arvense (ioo1), Polygonum vivi-
parum (ioo1) [the indices show the degree of coveringj, Brachythecium
plumosum (901), Rhacomitrium canescens v. epilosum (ioo1), Sphag-
num teres (ioo1) und Stereocaulon paschale (901) auf. ... Anzahl Ge-
fásspflanzen pro Quadrat 3-11”. Apart from the mosses, the same
species, and in similar quantities, as in the Calamagrostis associations
in Arnardalur and at Landmannahellir are found here. The picture
given by Nordhagen (1. c. p. 512) shows that the position of the Cala-
magrostis belt in the Nea valley in relation to other formations and
to the river corresponds to that of the Calamagrostis jaðar here. Other
authors record Calamagrostis associations from Scandinavia; thus
Henning (1895) mentions Calamagrostideta neglectae from the al-
luvions of Jemtland, and Tengwall (1925, p. 751) records the
same from the delta areas of the Sarek region. Hence it can be establisbed
that the Calamagrostis associations are of rather common occurrence
on alluvial formations both in northern Scandinavia and in Iceland.