Fróðskaparrit - 01.01.2006, Side 116

Distribution of Raunkiær’s life-forms
along altitudinal gradients in the Faroe
Islands
Útbreiðslan av lívshættum Raunkiærs niðan eftir
fjallasíðum í Føroyum
Anna Maria Fosaa', Jonas E. Lawesson(t) and Martin T. Sykes2
1 Faroese Museum of Natural History, Department of Botany, Debesartrød, FO-IOO Tórshavn,
Faroe Islands. E-mail anmarfos@ngs.fo
2 Lund University, Department of Physical Geography and Ecosystems Analysis, Solvegatan 13,
SE-223 62 Lund, Sweden.
Úrtak
Fyri at vita, hvar vøksturin í Føroyum skiftir frá at vera
arktiskur til at vcra tempereraður, kannaðu vit útbreiðsl-
una av lívshættum Raunkiærs niðan eftir fimm ymiskum
fjallasíðum. Eisini kannaðu vit, hvønn týdning gróðrar-
lagið, LOI (gløðitap) og árligur miðalhiti hava fyri út-
brciðsluna av lívshættum við hæddini. Okkara niður-
støða var, at tíðleikin av hemikryptofytum minkaði lin-
jurætt við hæddini, tíðleikin av therofytum og geofytum
vaks linjurætt við hæddini, og rásin, sum vísir tíðleikan
av charmaifytum sum funktión av hæddini hevur skap
sum parabil, við lægsta tíðleikanum á 400-500 m hæđd.
Tíðleikin av hemikryptofytum samsvarar cins væl við
lága gróðrarlagið sum við hæddina, men therofytamir
samsvara best við lága gróðrarlagið. Chamaefytamir
samsvara best við tann árliga miðalhitan, men geofyt-
arnir samsvara best við LOI. Kanningin vísir, at lutfallið
millum hemikryptofytar og chamaefytar broytist við
hæddini, sum vøksturin skiftir frá tempereraðum til
arktiskt eyókenni.
Abstract
To study the shift from temperate lo arctic vegctation
in the Faroe Islands, we quantitatively analysed the
distribution of Raunkiær’s life-forms along fíve
altitudinal gradients. We further tested the importance
of the non-climatic parameters of altitude, total
vegetation cover and LOI (loss on ignition), and the
climate variable of annual mean temperature in dcscri-
bing the abundance variation of life-forms. We found
that as altitude increased, the abundance of hemi'
cryptophytes decreased linearly; the abundance of
therophytes and geophytes increased linearly; and the
abundancc of chamaephytes varied parabolically, with
the lowest abundance around 400-500 m. The abun-
dance variation of hemicryptophytes seems to bc as wen
correlated with total vegetation cover as witli altitude,
while total vegetation cover was the best parameter to
describe the variation in abundancc of thcrophytes-
Annual mcan temperaturc was the most important
parameter for describing thc abundance variation of
chamaephytes and LOI was the most important
parameter describing the variation of geophytes. We
concludcd that the abundance relationship bctween
hemicryptophytcs and chamacphytes changed with
altitude as the vegetation changed from tcmpcrate to
arctic vegetation.
Fróðskaparrit 54. bók 2006: 114-130