Fróðskaparrit - 01.01.1998, Page 24

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A BIOGEOGRAPHIC ANALYSIS OF THE PLANTS IN THE FAROE ISLANDS
considered the most Faroese island in a
floristic context. It deviated signifícantly
from only one single island, namely Kunoy.
It is difficult to understand these results:
Hestur and Fugloy are significantly posi-
tively correlated. Nólsoy and Eysturoy are
significantly different in spite of their mu-
tual distance of less than 4 km. Sandoy is
significantly different from Streymoy de-
spite a mutual distance of 5.5 km and Hes-
tur’s position in between as a ‘stepping
stone’.
The many instances of significant devia-
tions must not overpower the characteristic
result of the comparisons which is that the
islands are very similar in a floristic con-
text.
If a comparison is made of the index of
pairs of islands lying near each other with
the index of all pairs of islands, there will
be a statistically certain tendency that is-
lands lying near each other are more relat-
ed floristicly than all the islands in general.
Conclusions
As regards the 17 largest of the Faroe Is-
lands, the proportion between the area (A)
of the islands and the number (S) of vascu-
lar plants may be described by the equation
S = 73.8 A0-20. On the basis of the frequen-
cy of the various species and on the as-
sumption that the distribution of the species
is random, a term can be set up (the null hy-
pothesis), which is largely able to describe
the proportion between the area and the
number of species.
This means that the area of the islands is
by far the most decisive factor when it
comes to explaining the number of species
on the islands.
The number of species on some islands
deviates somewhat from a sheer dependen-
cy on area. The northerly islands have few-
er species than could be predicted on the
basis of their area, a phenomenon which is
due to their northerly location (climate) and
their steep relief profile (height). The num-
ber of species on the small islands of Hes-
tur, Nólsoy and especially Koltur is dis-
tinctly above what could be anticipated.
The result of the present comparison of
the islands’ flora demonstrates that the flo-
ra of the islands is very homogenous. The
northerly islands, however, deviate from
the others. The southerly islands constitute
a somewhat more heterogeneous group.
The small islands are most closely related,
floristicly. Sandoy is the most deviant is-
land and Skúvoy the most Faroese of all is-
lands, in a botanical sense.
Acknowledgements
We would like to express our thanks to the Fróðskapar-
setur Føroya for their financial support to a study trip to
the Faroe Islands in 1985. The trip became the direct
reason why Erik settled down on the Faroe Islands for
four years and Hans for one year, during which period
we both worked at the Studentarskúlin of Eysturoy. We
are also grateful to Henning Adsersen for his assistance
and the many valuable discussions we have had with
him underway.
References
Adsersen, H. 1990. Intra-Archipelago Distribution
Pattems of Vascular Plants in Galapagos. Monogr.
Syst. Bot. Missouri Bot. Gard. 32: 67-78.
Arrhenius, O. 1921: Species and area../. Ecol. 9: 95-99.
Begon, Harper and Townsend 1990. Ecology, Indivi-
duals, Populations and Communities. Blackwell
Science.
Bengtson, S.-A. 1982: Lavere dyr pá land og i fersk-
vand. In: Nørrevang, A. og Lundø, J. (eds) 1982.