Fróðskaparrit - 01.01.2007, Qupperneq 126

124
THE VEGETATION OF GRASS ROOFS IN THE FAROE ISLANDS AND
THE SURROUNDING GRASSLAND VEGETATION - A STUDY FROM SANDOY
Conclusion
The observation that grass roofs have a
lower diversity than the vegetation from
which they were derived is confmned by
this study. Although no direct evidence ex-
ists, the difference in diversity between
ground and roof quadrats, the absence of a
correlation between the variation of the
roof vegetation, and the factors of aspect,
slope and the presence or absence of graz-
ing, indicate that an additional factor is
probably responsible for the lower floristic
diversity of the grass roofs. This may be
summer drought, although further research
would be needed to confírm this.
It is a pity that circumstances prevented
us from determining more fully the many
factors that are likely to come into play re-
garding the floras of grass roofs, although
various directions for future research
might be suggested. What of the age of the
roof turfs, and does aspect result in roof
segments being replaced at different
times? Where roofs are patched, does
quantification of the flora become a near-
impossible task? What is the precise geo-
graphical origins of the turfs and have
these changed within living memory? How
many species (wind-blown propagules) es-
tablish on the species-poor roofs compared
with the surrounding vegetation where
species competition is much higher?
Would monitoring of local climates (in-
cluding roof micro-climates along with
roof drainage characteristics) reveal im-
portant influences on changing roof floras?
Just as difficulties now face an assess-
ment of once widespread Faroese peat-cut-
ting activities (Sigvurdsen 2006), it may be
the case that the passage of time is making
it almost impossible to coinpare floristic
changes that have applied traditionally in
the face of modem roofíng practices. This
factor alone may make the assessment of
differences in roof vegetation between and
within settlements, or even as a result of
family tradition, a near-impossible task.
Nevertheless, it is hoped that the present
paper might encourage further investiga-
tion of a fascinating element of the Faroese
settlement landscape.
Acknowledgements
This paper arises from fieldwork supported by the
Leverhulme Trust. Dorete Bloch is thanked for her en-
couragement and paticncc and the constructive com-
ments of Per Enckell were much appreciated.
References
Hansen, K. 1966. Vascular plants in the Faeroes. Hori-
zontal and vertical dislribution. Dansk Botanisk
Arkiv 24: 1-141.
Hansen, K. and Jóhansen, J. 1982. Flora and vegetation
of the Faroe Islands. Monographiae Biologicae 46:
35-52.
Hayek L.C. and Buzas M.A. 1997. Surveying Natural
Populations. Columbia University Press, New
York.
Hill, M. O. and Gauch, H.G. 1980. Detrended corre-
spondence analysis: an improved ordination tecli-
nique. Vegetatio 42: 47-58.
Holden, T.G. 1998. Historic Scotland Technical Advice
Note 13: The Archaeology of Scottish Thatch. His-
toric Scotland, Edinburgh.
Jóhansen, J. 1985. Studies in the vegetational history of
the Faroe and Slietland islands. Annales Societatis
Scientiarum Færoensis Supplementum XI. Tór-
shavn.
Jóhansen, .1. 2000. FøroyskJlora. Fosaa, A.M. and Ras-
mussen, S. (eds.), Føroya Skúlabókagrunnar, Tór-
shavn.
Lyngbye, H.C. 1822. Anmærkninger til Kort Efterret-
ning om Færóeme, efter Sir Mackenzie. In: Collin,