Náttúrufræðingurinn - 1995, Blaðsíða 104

2. It could be snow cover as snowpatch plants
such as Vaccinium myrtillus increase as we go
up axis 2. Fig. 7 and Table 3 show the relation-
ship between different plant species and the
result of the ordination.
The TWINSPAN program gave four groups
(Fig. 8). Good agreement was between the
TWINSPAN classification and the ordination
(Fig. 9). The most common woody plants for
groups A/B were Empetrum nigrum, Betula
nana and Calluna vulgaris, but in groups C/D
willows, especially Salix phylicifolia, were
important.
Ptarmigan numbers in sample points and the
site ordination show that the greatest number
of birds are in the lower left corner of the
graph and numbers decrease as we go up both
axes (Fig. 6 and Fig. 12). Similar picture
emerges if we compare ptarmigan numbers
and the TWINSPAN classification (Table 4).
The study shows that there is a connection
between type of vegetation and ptarmigan den-
sity. Certain types of heathland vegetation
(Betula nana heaths, Steindór Steindórsson
1981) are characterized by a low density of
ptarmigan as compared with other types
(heather heaths). This difference in density is
maintained all through the 10-year ptarmigan
cycle (Fig. 13). The author regards this as the
first step to establish whether remote sensing
can be used to determine breeding distribution
and population size of Rock Ptarmigan over
extensive areas in Iceland. The next logical
step would be to study whether we can discern
heathlands from the other main vegetation
types by means of remote sensing and further
classify the different types of heathlands and
connect that classification with ptarmigan
density (see Palmeirim 1988, Avery and
Haines-Young 1990, Ferguson 1991, Pearce
1991, Wallin et al. 1992).
PÓSTFANG HÖFUNDAR /
AUTHOR'S ADDRESS
Ólafur K. Nielsen
Náttúrufræðistofnun Islands/
Icelandic Institute of Natural History
Pósthólf/Box 5320
IS-125 Reykjavík
Iceland
Viðauki/Appendix
Listi yfir jurtir sem komu fyrir í gróður-
mœlingum í Suður-Þingeyjarsýslu í júní til
ágúst 1993. Plöntulieiti eru skv. Herði
Kristinssyni 1986. - List of plants re-
corded.
Jafni1
Elfting2
Beitieski
Einir
Brjóstagras
Fjalldrapi
Lambagras
Kornsúra
Súrur'
Geldingahnappur
Grávíðir
Grasvíðir
Loðvíðir
Gulvíðir
Krækilyng
Sortulyng
Beitilyng
Sauðamergur
Aðalbláberjalyng
Bláberjalyng
Holtasóley
Maðra4
Blóðberg
Smjörgras
Vallhumall
Undafífill
Túnfífill
Lycopodiaceae
Equisetum sp.
Equisetum variegatum
Juniperus communis
Thalictrum alpinum
Betula nana
Silene acaulis
Bistorta vivipara
Rumex sp.
Armeria maritima
Salix callicarpaea
Salix herbacea
Salix lanata
Salix phylicifolia
Empetrum nigrum
Arctostaphylos uva-ursi
Calluna vulgaris
Loiseleuria procumbens
Vaccinium myrtillus
Vaccinium uliginosum
Dryas octopetala
Galium sp.
Thymus praecox
Bartsia alpina
Achillea millefolium
Hieracium spp.
Taraxacum spp.
'Ekki var greint á ntilli litunarjafna Diphazium
alpinum, lyngjafna Lycopodium ammotinum,
mosajafna Selaginella selaginoides og skolla-
fingurs Huperzia selago. - Lycopodiaceae re-
fers to Diphazium alpinum, Lycopodium amm-
otinum, Selaginella selaginoides and Huperzia
selago.
2Ekki var greint á milli klóelftingar Equisetum
arvense og vallelftingar E. pratense. - Equi-
setum sp. refers to Equisetum arvense and E.
pratense.
3Ekki var greint á milli túnsúru Rumex acetosa
og hundasúru R. acetosella. - Rumex sp. refers
to Rumex acetosa and R. acetosella.
4Ekki var greint á milli hvítmöðru Galium
normanii og gulmöðru G. verum. - Galium sp.
refers to Galium normanii and G. verum.