The Botany of Iceland - 01.12.1912, Síða 56

42
H. JÓNSSON
3. THE AIR.
The climate is of special importance to that part of the algal
vegetation which is exposed during Iow-tide. The temperature is
possibly of least importance in a climate where high and very low
degrees of temperature do not occur, or are, at any rate, rare. The
degree of humidity of the air and the cloud-covering are, on the
other hand, liighly important to the algal vegetation which is left
dry. The movements of the air are also of importance, especially
as it produces movements in the sea.
A. The Temperature.
The following means (19 years)1 from a number of stations on
different parts of the coast are here given for the elucidation of the
thermal conditions.
E. Iceland Winter Spring Summer Autumn The year
Papey , . . . - í.i 0.1 6.0 3.3 2.1
Berufjörður 0.8 7.6 3.5 2.6
N. Iceland
Raufarhöfn . . . . -4.0 — 1.9 6.5 1.6 0.5
Grímsey , ... — 2.3 — 1.5 6.1 2.9 1.3
SW. Iceland
Stykkishólmur , . . . - 2.2 0.8 8.9 3.9 2.9
S. Iceland
Vestmannaeyjar 3.8 9.7 5.2 5.0
Eyrarbakki ... 2.0 2.1 10.2 3.5 3.5
From the figures given above it will be possible to form an
opinion of the tliermal conditions in the places mentioned, and
these are altogether such that an algal vegetation left dry can thrive
everywhere along the coast. The extremes will not have a sufficiently
injurious effect on the vegetation for it to be noticeable in the long
run. High degrees of temperature, about 20° C for example, occur
rarely in the summer, and will have no permanent effect. Very low
degrees of temperature in the winter will not injure the vegetation
left dry to any extent worth mentioning, as it is then partly pro-
tected by snow (at the very top) and partly by ice.
I do not consider the cold in the winter injurious to the vege-
tation which is left dr}r, as the algæ certainly endure being frozen
fairly well. At Ieast I have seen uppermost in the littoral zone,
1 Willaume-Jantzen, Meteorologiske Middeltal og Extremer for Færöerne,
Island og Grönland, Kjöbenhavn, 1899.