Fróðskaparrit - 31.12.2000, Síða 43

EITT YVIRLIT YVIR FØROYSK PLANTU S AMFELØG
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Heath Vegetation
Heath vegetation is common throughout
the Faroe Islands. The dominant dwarf-
shrubs are Calluna vulgaris, which is com-
mon up to 400 m, Empetrum nigrum ssp.
nigrum and Empetrum nigrum ssp. her-
maphroditum, which may occur even high-
er, and Erica cinerea, which is less com-
mon and occurs only below 300 m.
Other dwarf-shrubs commonly found are
Vaccinium myrtillus, which is very com-
mon, while V uliginosum and V. vitis-idaea
are less frequent. The common herbaceous
plants in the dwarf-shrub heaths are
Narthecium ossifragum, Juncus squarrosus
at wetter sites, and Potentilla erecta, Nar-
dus stricta, Carex pilulifera, Galium sax-
atilis, Hypericum pulcrum, and Cornus
suecica at drier sites.
The heath has primarily been studied by
Ostenfeld (1905-1908), Bocher (1940),
Hansen (1967), and Hobbs and Averis
(1991). Large areas with true heath, domi-
nated by Calluna and Erica are not found in
the Faroe Islands, since herbs and mosses
are numerous in the heaths. Due to the
moisture of the heath, the name “heather-
moor” would be more suitable. The nearest
equivalent to these Calluna heaths is to be
seen in the Shetland Islands, in westem
Norway, and in Scotland (Bocher, 1940).
The Faroese heath has a more oceanic char-
acter than these. In addition, the Faroese
heaths are heavily grazed. When grazing
becomes particularly intensive, Nardus
strícta dominates the heath entirely.
Heaths occur primarily in the southern,
lower parts of the larger islands. Smaller
patches also appear on most of the islands,
where the valleys are broad enough to al-
low the sun to shine on the fairly dry slopes
with a southerly exposure.
The driest of the heaths is the Calluna
vulgaris - Eríca cinerea association. It is
exclusively found on south and west facing
sites. The fact that it tends to be confined to
the microclimatically most favourable sites
indicates that this vegetation type has its
northern limit of distribution in the Faroe
Islands. It never extends above 300 m and
Erica cinerea has its northern limit of dis-
tribution here. This association is charac-
terised by species like Potentilla erecta,
Agrostis canina, and Scirpus caespitosus.
Hobbs and Averis (1991) found that
these plant communities had much in com-
mon with the British Calluna vulgaris - Er-
ica cinerea association. Comparing this
vegetation to equivalent vegetation in the
Nordic area, it is observed that some char-
acteristic species are missing in the Faroe
Islands, i.e. Arctostaphylos uva-ursi and
Erica tetralix. A general difference be-
tween these vegetation types in the Faroe
Islands and similar vegetation types else-
where is the sparse representation of
lichens and the ubiquitous presence of Po-
tentilla erecta and Nardus stricta in the
Faroe Islands. This is probably due to
heavy grazing or a combination of grazing
and the wet climate.
With an increase in humidity, there is a
characteristic transition between the Callu-
na vulgaris — Erica cinerea association and
the Calluna vulgaris association and the
Empetrum - Vaccinium association (Boch-
er, 1940). Hobbs and Averis (1991) found
that the moist heath had similarities to the