Fróðskaparrit - 31.12.2000, Blaðsíða 39

EITT YVIRLIT YVIR FØROYSK PLANTUSAMFELØG
43
west Iceland, on Jan Mayen, in parts of east
and west Greenland, and on Baffin Island.
The total thickness of the Faroese basalt is
3,000 m and consists of three basaltic se-
ries, characterised by alternating layers of
basalt, lava, and tuff. In some places, car-
boniferous strata with identifiable fossils of
Metasequoia occidentalis have been found
(Rasmussen and Koch, 1963). The layered
structure of the bedrock gives the landscape
its characteristic look of more or less slop-
ing surfaces truncated by vertical cliffs.
The basalt horizon dips slightly in a north-
east direction in the southern part of the is-
lands and in a south-east direction in the
northern part of the islands. The northern
and western sides of the islands have steep
cliffs, while the eastern side of the islands
slopes gently into the sea. In some places,
especially on the eastern side of the islands,
peat bogs are found below sea level, indi-
cating a recent submergence of the land to
the east. These peat horizons are seldom
thicker than 1 -1.5 m on average.
The climate is highly oceanic with cool
summers and mild winters. It is greatly in-
fluenced by the warm North Atlantic Cur-
rent and by proximity to the common cy-
clone track in the North Atlantic region.
Consequently, the climate is humid, vari-
able, and windy. The warmest months are
July and August with a mean temperature
of 11°C (lowland) and the coldest month is
February, with a mean temperature of 4°C
(lowland). Precipitation reflects the topog-
raphy of the islands. The coastal areas re-
ceive around 1,000 mm per year increasing
to more than 3,000 mm in the central re-
gions. Wind is one of the main factors af-
fecting the vegetation both directly and by
salt spray, which is carried inland.
The soils are developed from fairly ho-
mogeneous, basalt parent material under
humid and cool conditions. The time the
processes have had to function is short on a
geological timescale - about 10,000 years.
The soils are continuously wet or moist and
generally have a thick organic horizon.
They are strongly acidic with high cation
exchange capacities and low base satura-
tion. The soils higher up are more minero-
genic because of much stronger erosion.
The soil here is less acidic and the vegeta-
tion forms grassland and grassy moors.
These constitute the most important pas-
tures for the thousands of grazing sheep.
The islands are heavily grazed, thus, “nat-
ural” vegetation is rare. In the bottom of
valleys, in depressions and other wet areas,
mires have developed. The basis for the
marsh vegetation is peat, which has played
an important role for the Faroese popula-
tion right up to the present time. The cut-
ting of peat was very common and artificial
depressions have been formed in the ter-
rain, which have promoted even larger ar-
eas of marsh vegetation.
Vegetation Classifícation
and Plant Communities
Due to the extreme oceanic climate, it is
difficult to delimit plant associations. The
differences are small compared to other
countries and it is necessary to indicate a
gradual transition from one association to
another.
Various methods and terms have been
used to classify the vegetation of the Faroe