The Botany of Iceland - 01.12.1945, Page 154

IV. THE VEGETATION AND THE
ALTITUDE
One of the tasks which will repay attention is to observe the rela-
tion of the vegetation to the altitude and in connection with it its rela-
tion to the exposure. Since relatively few mountain sides covered with
vegetation occurred within the areas investigated by me, I had to re-
frain from further observations in this respect. I made, however, two
series of analyses with a view to the distribution of the associations
according to altitude. Both series are from Landmannaafrjettur, from
mountain sides without noteworthy grooves or ridges, but with fairly
even slopes. The first series (Tab. XXVI) is from the south side of
Loðmundur.
I shall then describe the individual analyses.
Analysis i was made at the foot of the mountain at an altitude of
c. 620 m. The locality is a sandy flat rather poor in species, but as soon
as we proceed higher up the mountain side, a luxuriant brekkur vegeta-
tion commences. Analysis 2 is from an altitude of c. 650 m. The other
analyses were made at vertical intervals of c. 50 m.
The next 200 m support a similar vegetation to that shown by
analyses 2-5. Each analysis comprises many species (22-27), and the
total of points is very high (900-1050), but the difference in altitude
does not seem to have any material influence on these conditions. The
biological spectra show the increase of the arctic species with increas-
ing altitude. No regular change is observable in the conditions of the
life-forms. The Ch percentage is lowest in analysis 4, but at the same
time the H percentage is lowest, too. The G percentage decreases fairly
evenly with the altitude. Phanerogams always dominate physiognom-
ically, Gramineae, in particular, are very conspicuous, though herbs
are also found. The Ch are not conspicuous physiognomically in spite
of a high percentage. With analysis*6 a change can be distinguished;