Fróðskaparrit - 01.01.1998, Blaðsíða 20

26
A BIOGEOGRAPHIC ANALYSIS OF THE PLANTS IN THE FAROE ISLANDS
zones is generally more sparse than the flo-
ra of the lowlands. Hansen (1966) fmds that
out of 262 naturally occurring species on
the Faroe Islands, 83 species have a line of
300 metres above which they do not occur
and 79 species are confined to areas lying
lower than 300-600 metres. Alternatively, a
mere 16 species solely occur above 300
metres. In the lowland zone, a total of 246
species are found, in the intermediate zone
173 species and in the mountain zone a to-
tal of 100 species.
An island with a high relief profile con-
tains at least one habitat more than an is-
land without the mountain zone, but it takes
place, so to speak, at the expense of low-
land areas, considering that the latter areas
are floristicly most diverse, islands domi-
nated by high mountains will hold fewer
species.
The soil conditions of the islands are so
homogeneous that it can barely have an im-
pact to account for the different number of
species of the islands. The common isola-
tion of the individual islands is apparently
irrelevant to the number of species on the
islands. Possibly because the islands are lo-
cated so near one another.
Apart from the geographical location
(north-south) of the islands and their relief
profile, it is difficult to account precisely
for the deviations from the null hypothesis.
Six islands deviate more than 20%. In the
latter group are Borðoy and Viðoy - both
northerly and high and they deviate in a
negative respect. Stóra Dímun, Hestur and
Figure 3. Koltur hasfar more species than could be anticipated. The reason is probably that it has a lot offertile
lowland, and despite its smallness, it reaches a height of479 m. Finally its accessibility has the effect that it is
possible tofmd many species within a short time.
Mynd 3. f Koltri eru nógv fleiri sløg, enn vit skuldu væntað. Grundin er helst, at har er sera nógv fruktagott
láglendi, og hóast oyggin er lítil, er hon 479 m til hæddar. Eisini hevur tað, at hon er so atkomilig, við sær, at tað
ber til at finna nógv sløg eftir stuttari tíð.