Rit (Vísindafélag Íslendinga) - 01.06.1939, Blaðsíða 16

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iife-form Ch, and Ch reaches no greater figure than this
elsewhere. On the other hand the comparatively high Th %,
11,1—14,3 is worthy of notice, as it covers the character-
istic plants of the plant-formation and comes under E 2
and E 3; they consist of plants of the good season, summer
plants. It will scarcely be possible to find a better corres-
pondence of life-form to the climate or of climate to the
life-form than under just these circumstances, where the
soil is reclaimed sand which contains a minimum quantum
of nourishment, and is subject to constant changes due to
wind and the direction of wind, and is at all times depend-
ent for heat and moisture on the air. Thus the life-forms
here are a direct product of the climate; temperature in
July 10,9° average, and the average rainfall for the same
month 90 mm, cf. tables 1—2. A is only 33,3—28,6 % and
Ch the same but Th is 11,1—4,3%. The sand is the plant-
formation of the life-form Th.
2. The Sandy-gravel plant-formation. The soil is dry
and sandy and loose on the surface, but closer, more mixed
with clay and damper than the sand, and the distribution
of species is 1,4—1,8, i.e. twice as much as in the sand,
though the no. of species is the same, 5—6. Agrostis alba
is only found in this plant-formation- If there is little on
the biological spectrum yet it appears that the A % figure
is very low, only 7,1—22,2, and similarly the Ch % figure
14,3—38,8. These figures are quite natural here as in the
sand, as the surface of the soil is dependent on the caprices
of the storms (wind force 5, cf. Table 1), and there is
practically no snow in the winters. In the summer the
sandy surface gets comparatively hot, though not so much
that the Th life-forms obtain foothold there, and it reduces
the amount of the Ch. Geophytes are barred as in the sand
because of the loose soil.
The sandy-gravel is therefore the plant-formation of
the indifferent Hemikryptophytes, not because of the H.
themselves but rather because other life-forms are ex-
eluded.