The Botany of Iceland - 01.12.1912, Blaðsíða 128

114
H. JÓNSSON
The Surf-belt, as previously stated, occurs at the upper
boundary of the Fucus-association on rocky coasts which are ver}'
much exposed. I have seen such a belt at 0ndverðarnes in SW.
Iceland, in the Vestmannaeyjar in S. Iceland and at Vattarnes in
E. Iceland. Strömfelt (70) has noticed a similar belt on Seley in
E. Iceland. It will prohably be found, on further investigation, that
the surf-belt is far more widely distributed along the coasts than
is recorded above. As a rule, the individuals in this belt are of low
growth; the frond is leathery, and very thick in proportion below,
and rounded, but tapering evenly upwards and becoming thinner;
ahove, it is often excessively branched. The height of the individuals
varies to some extent, f. dendroides is the highest, while f. exposita
attains only an insignificant height (5—9 cm.). A similar surf-helt
occurs in the Færöes (Börgesen, 12), although the vegetation is
possibly more luxuriant there than in Iceland.
TheWave-belt(Fig.6) comprises the ordinary Fucus inflatus-be\t.
As a rule, it is exposed to the movement of the waves, a movement
which is often very violent indeed; more rarely it is exposed di-
rectly to the breakers. Here the species occurs in its tvpical form
which shows a considerable variation in the breadth and consistency
of the thallus. In very exposed places the branches of the frond are
comparatively long and narrow and leathery, but where the move-
ment of the waves is less felt, the frond is usually broader. The
vegetation of this belt is generally very luxuriant, and covers the sub-
stratum entirely. Often, however, the vegetation occurs in patches,
owing to the surface-features of the shore. Sucli a mode of occur-
rence is met with, for instance, where the shore is a wild talus of
debris consisting of large scattered blocks of stone, or where the
solid rock has a similarly uneven surface owing to erosion by the
sea. There a belt is formed around each block of stone, while the
hollows between them are occupied by semi-littoral or sublittoral
vegetation, or by stragglers from these zones.
The Calm Belt is lowest of all, often at the boundary between
the constantly submerged and the lower littoral vegetation, and some-
times forms small offslioots of vegetation1 below that boundary.
Here the movement of the waves is least felt, and the frond of the
1 The species varies froni the principal form to two kinds of dwarf-forms —
a small “surf-form” of tougli texture, and a small “pool-form” of delicate texture.
The pool-form-association (F. in/lalus' f. linearis) may be regarded as the fourth
belt, which should then be termed the Delicate Belt (see under The Vegetation
of Tide-Pools, p. 125).