Fróðskaparrit - 01.01.2009, Side 119

PLANTUVØLIR 0G VØLAMÍGG] (DIPTERA: CECIDOMYIIDAE) í FØROYUM
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acquainted with admirable work of Marcello
Malpighi.
The literature on galls is very extensive.
Houard (1908-1909) gave a rich bibliography
including about 1000 references, Mani
(1964) in his comprehensive book „The eco-
logy of plant galls" included 1300 references
that refer to the problem of galls, Buhr
(1964-1965) in his two-volume book with
identification keys to plant galls gave even
2700 references. Useful data on biology and
ecology of gall causing organisms may be
found in books published by Ananthakrish-
nan (1984), Shorthouse and Rohfritsch
(1992), Redfern et al. (2002), Raman et al.
(2005) and Ozaki et al. (2006).
In the period 1955-2008 we investigated
gall midges and their galls in many countries
of Europe at more that 1800 localities
(Skuhravá and Skuhravy, 1998). In August
2005 we had an opportunity to spend one
week in Tórshavn, the capital of the Faroe Is-
lands. We did as it we usually do during our
field trips and excursions in various countries
of Europe, and searched for galls on various
host plants.
Study area
Faroe Islands (Føroyar, Faroes, Færøerne) is
an interesting country. It is a group of 18 is-
lands of various size situated in the middle
of the North Atlantic between latitude 61°
20' N and 62° 24' N and longitude 6° 15' W
and 7° 41' W. They measure from north to
south 113 km, from west to east 75 km and
the total land area is 1399 square kilometres.
They are halfway between lceland and Nor-
way and the nearest land is Shetland to the
south-east, about 300 kilometres away. Faroe
Islands were formed in Tertiary times, mil-
lions of years ago, from submarine outpour-
ings of basaltic lava, and belong geologically
to the North Atlantic Basalt Province. Lava
and ashes from volcanic eruptions have
formed basalt plateaux. Later the glaciers of
the Glacial Age have transformed it into a
mountainous group of islands with deep val-
leys and narrow fiords. The highest point is
882 m, the average elevation 300 m above
sea level. A mild and damp oceanic climate
prevails owing to the Gulf Stream which
meets a cold polar current deflected from
lceland. Average temperature in summer is
11° C, in winter 3° C. The weather changes
very quickly and storms are violet and sud-
den. Fog, showers and sunshine follows at
short intervals (Schlei and Moberg, 2003).
The natural vegetation is dominated by
arctic-alpine plant species, viz. wild flowers,
grasses, mosses and lichens. Most of the
lowland is grassland and some heath. Only
about 6% of the total area has been culti-
vated. The rest is waste land covered with
grasses along the seaside and with poor
vegetation in higher country. Above 600
metres mosses and lichens predominate.
About 340 native wild plant species grow in
the Faroe Islands (Fosaa, 2000) and about 60
introduced species. The natural vegetation is
characterised by lack of wild trees and
shrubs. In the past birch (Betula spp.) and
juniper (Juniperus communis) occurred on
islands and their remnants were found in
peat bogs. Salix herbacea, a native species, is
growing in the mountains. Recently various
trees and shrubs were introduced and are
planted in private gardens around houses.
Forest plantation, founded in Tórshavn in
1902, forms now a nice park with relatively
high trees and shrubs.