Fróðskaparrit - 01.01.2006, Page 120

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DISTRIBUTION OF RAUNKIÆR’S LIFE-FORMS
ALONG ALTITUDINAL GRADIENTS IN THE FAROE ISLANDS
Names of lo- calities Lutitude Longitude Length Maximun Altitude Aspect
1 Somfelli 62°04'10”N 6°57'25"W 3.7 Km 749 m a.s.l. N
2 Mosarøkur 62° 11 '05" N 7°10'52"W 4.0 Km 756 m a.s.l. SW
3 Ørvisfelli 62°12'32''N 7°09'17”W 1.2 Km 783 m a.s.l. N
4 Gráfelli 62°18'41 "N 6°59'48"W 2.9 Km 856 m a.s.l. SW
5 Villingar- dalsfjall 62°22'53"N 6°33'13"W 1.3 Km 841 m a.s.l. s
Table 2. Details of the five investigated transects.
meso-plots were subdivided into 25 (0.1 x
0.1 m) micro-plots and the presence/absence
of plant species was noted for each micro-
plot. In this way, the abundance of species,
ranging from 1 to 25, was determined for
each meso-plot.
The total vegetation cover was estimated as
the mean percent coverage of each meso-
plot and the slope was measured. (Table 3).
One soil core (5 cm diam. x 10 cm deep)
was sampled from each meso-plot after the
vegetation had been removed.
Loss on ignition (LOI) was determined
by ashing a soil sample at 550°C in a muf-
fle fumace for three hours. The pH was de-
termined with a Radiometer PHM 240 pH-
meter after mixing dried soil with distilled
water. (also see Lawesson et al., 2003)
Soil temperature at I cm depth, was also
measured hourly at 50 m altitudinal inter-
vals during the years 1999 and 2001 using
TinyTag data loggers.
To calculate the characteristic values, we
computed annual values for fíve key pa-
rameters: the annual mean temperature
(Tav); the mean temperature of the warmest
month (Tmax); the rnean temperature of the
coldest month (Tmm); growing degree days
(GDD), and the number of days with snoW
cover. GDD was calculated by summing the
temperature excess over 5°C for all hourly
observations in a year and dividing by 24
(Molau and Mølgaard, 1996). Number ot
days with snow cover was determined by
taking the number of days with daily tern-
perature ranges below 0.5°C and the mean
daily temperature below 1 °C. The two yeai'
period of measurement was from Septern-
ber 1999 to August 2001 for all the moun-
tains except one, where we used the yearly
periodAugust 2000 to July 2001 (Fig. 1,1°"
cality 2). Details of the measurements and
the results have been reported by Fosaa et
al. (2001).