The Botany of Iceland - 01.12.1945, Síða 51

THE VEGETATION OF CENTRAL ICELAND
393
(Tables IV-VI A and B)
On considering the biological spectra from the mýri formation,
we shall see that both the number and the density of the species are
much greater than in the flói; thus in the mýri 6-16 species occur in
one analysis. It is variable which group of species dominates; in some
associations it is the southern species, whereas arctic species dominate
in others. Of the life-forms, G dominates in only some few associations,
while H dominates in others, and the Ch percentage is, as a rule, com-
paratively high. In this respect there is a distinct difference from the
flói, in which G almost without exception is the dominating life-form.
I have compared these spectra from the alpine mýri with some of
the available spectra from the lowland mýri, thus with Molholm
H a n s e n’s results (1. c. pp. 68 and 87) and my own investigations on
Melrakkasljetta (Steindórsson 1936, pp. 445-448) and in the
region Flói in southern Iceland (Steindórsson 1943, pp. 91-95).
In MoIholmHansen’s and in my investigations in southern Ice-
land the lowland mýri shows a higher E percentage than A percentage,
but on Melrakkasljetta the A percentage is the highest; thus there is a
great similarity between the species-group spectra from Melrak-
kasljetta and the highland, whereas the life-form spectra of the alpine
mýri agree most closely with my results from the southern part of the
country. In my opinion this would seem to indicate that the life-form
spectra and the species-group spectra cannot be used in the same way
as a means by which to judge of the life conditions under which the
different plant formations live.
The most important associations of the alpine mýri are as follows:
1. Carex rariflora—Cal. neglecta—Erioph. Scheuchzeri-Ass.
(Tab. V, 5-7).
The dominant species in this association are Carex rariflora and Ca-
lamagrostis neglecta, the former being especially conspicuous physiog-
nomically. The species of Eriophorum are conspicuous, also, notably
E. Scheuchzeri. The relationship of this association with the flói as-
sociations 4-6 is very remarkable. The main difference is that the
present association is found on drier ground and the moss vegetation
is much more developed than in the corresponding flói association. The
analyses at hand were carried out at Landmannahellir, the only place
in the highland where this association attains some distribution, though
it has also been met with in Arnardalur and Hvannalindir. G is the
The Botany of Icland. Vol. III. Part IV.
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