Fróðskaparrit - 01.01.1987, Page 100

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THE ECOLOGY OF SOME MARINE AND MARITIME LICHENS
ornitocoprophilous species Phaeophyscia
orbicularis seems to have a certain degree
of dominance in both these zones.
Almborn (1955) and Fletcher (1978)
used the ornitocoprophobic species Rhiz-
ocarpon constrictum as an indicator for the
x.s.l. zone. In places where the influence of
guano becomes greater this species disapp-
ears and more ornitoprophilous species
such as Anaptychia fusca become dominat-
ing.
Other ornitocoprophilous species which
are found in the localities but not mention-
ed in tab. 4 are Aspicilia caesiocinerea,
Physcia tenella var marina, Lecanora mur-
alis, and Parmelia sulcata.
7. Discussion
The profiles investigated show that the
seashore zonation, which is seen in North-
ern Europe also occurs in the Faroe
Islands. The main difference is that the sea-
shores of the Faroe Islands are poorer in
number of species, and therefore lack some
characteristic species.
The e.l. zone is 1 and 2 m respectively
wide in the two investigated localities and
is dominated by Verrucaria maura and V.
mucosa that were the only species which
were found. On loc. 7 Arthopyrenia halo-
dytes was found growing on Patella vulgar-
is.
Almborn (1955) found Verrucaria micro-
spora, V. ditmarsica, V. erichsenii to be
dominating on Halland Váderð, and
Knowel (1913) found Verucaria mucosa,
V. microspora, V. striatula, and Arthopyr-
enia halodytes to-be dominating on the sea-
shores in the northern Ireland. Verrucaria
striatula, V. microspora, V. ditmarsica, and
V. ceutocarpa are only found once in the
Faroe Islands, and appear to be rare
here.
Verrucaria maura is the only species oc-
curring in l.f., and thalli of Caloplaca mar-
ina, C. thallincola, and Lichina confinis
constitute the upper border of the zone.
Lichina confinis and Caloplaca marina
are here used as indicators for m.s.l. zone.
The ornitocoprophilous species Leca-
nora poliophaea are widespread in this
zone, but since it is equally abundant in the
s.s.l. zone it is not used as an indicator.
This same phenomenon is seen in Iceland
(Baldursdóttir 1985) and on Moskenesoya
(Degelius 1938).
It can be discussed whether it is appro-
priate to talk about a mesic and submesic
supralittoral zone in the Faroe Islands, be-
cause of the uniform dominance of Leca-
norapoliophaea in both zones. But at a lev-
el 7 respectively 8 m away from the sea
level, the foliose Xanthoria parietina in-
vades and is relatively constant throughout
the zone. Besides Xanthoria parietina,
there is also an invasion of several other fo-
liose species at this level on the seashore. It
is on the basis of these foliose lichens that
the supralitthoral zone of the Faroe Islands
can be divided in one mesic and one sub-
mesic supralitthoral zone.
Anaptychia fusca, Ramalina siliquosa,
and Rhizocarpon constrictum are used as
indicators for x.s.l. most places in northern
Europe. As Anaptychia fusca is the only
new lichen in this zone it is used as an indi-
cator here.
Ramalina siliquosa was only found on
the vertical surfaces and only sporadically