Fróðskaparrit - 01.01.1987, Page 57

WHEN, HOW, AND WHENCE?
61
1972, other insects, Koponen 1985). Twen-
ty-three plantations, most of them between
1 and 5 ha (some less successful) have been
established.
The above historical account relies on
West (1972) and Young (1979).
Summary of the immigration
to and colonization of the Faroes
The foregoing account can be conveniently
summarized as follows:
1) A large-scale immigration event (but
not necessarily colonization to the same
degree) occurred some time between 10000
and 9000 BP from coastal areas in western
Scandinavia and western Scotland with the
Hebrides (Fig. 2).
2) An immigration trickle occurred with
driftwood from the American continent
and the northern part of Eurasia; the for-
mer probably starting earlier than the latter
(on account of ice conditions in arctic areas
and forest development in northern Eur-
asia).
3) Aerial immigration probably occurred
continuously from the moment the Faroes
became available to immigrants. This kind
of dispersal has probably increased in in-
tensity, and with a succession of species, as
a consequence of the increasing species
richness and changing faunal composition
in the source areas in NW Europe.
4) Immigration with Man has occurred
during approximately the last 1100 years (if
one disregards the earliest contacts with
Ireland as having had a negligible effect).
The main periods and directions have been
(Fig. 3):
a) From Shetland and western Norway
from about AD 850, with small additions
from Ireland, the Orkney Islands, and Ice-
land, up to about AD 1550.
b) From Denmark and surrounding
areas during the period of the trade mono-
poly (AD 1529 - 1536 to 1856)
c) From indeterminable directions dur-
ing the last 100 years, although probably
still with a preponderance of NW Europe-
an contacts.
5) In addition to this immigration of spe-
cies to the Faroes (1-4) a dispersal between
and within the separate islands in the group
has occurred continuously but possibly
more intensively during the second period
of inner colonization (AD 1200 - 1300);
during the period of the trade monopoly,
and in recent times.
The biogeographical position
of the present-day terrestrial
invertebrate fauna of the Faroes
Any qualitative assessment of the faunal
diversity and taxonomic composition of the
present terrestrial invertebrate fauna of the
Faroes rests on how complete species lists
are (reflecting the degree of coverage and
collecting effort). To illustrate the position
of the Faroes as concerns faunal richness,
and similarity to neighbouring areas, I have
chosen to summarize the information avail-
able on four taxonomic groups (Coleop-
tera, Araneae, Lumbricidae and Gastro-
poda) which are believed to be rather well
known in most of the areas concerned. The
literature sources are given in the legend of
Fig. 4; it should be noted that information
from the Orkney Islands is more incom-
plete than for the other areas.
Some salient features emerge from the
numbers in Fig. 4.