Rit (Vísindafélag Íslendinga) - 01.06.1975, Side 47

or fluvial sand, and hence there is no moss growth. Analyses 1-2
are from Hvannalindir (620 metres above sea level) and 3 is from
Kýlingar (580 metres above sea level) with no. 4 emanating from
Jökuldalur (approx. 580 metres ahove sea level). At all these sites
there are flói borders where the soil is very sandy and flooded in
spring. Analyses 5-6 are from Hvítámes (420 metres above sea
level) where conditions are similar to those of the above mentioned
locations, with the exception of no. 6 which is from a wetter area,
since C. rariflora is most prevalent there. Analyses 7—8 are from
Holtavörðuheiði (400-420 metres above sea level) from a flói pro-
per without blown sand or inundation apart from that which col-
lects in the soil during thaw or precipitation. There E. angustifolium
prevails altogether, although Calamagrostis retains its frequency.
On the Holtavörðuheiði this sociation is common in the drier flói
tracts where it extends over fairly large areas. I have not elsewhere
seen it so widely distributed.
13. E. angustifolium — Betula nana — Vaccinium uliginosum
sociation (Tah. IV A-B 1-5)
Five observations are counted here, from Orrastaðir in Húna-
vatnssýsla, Skjaldfannardalur in Norður-lsafjarðarsýla, Laugarholt
in Borgarfjörður, and from Snæfellsnes and Mýrar. But it occurs
in many parts of the country. What sets it apart from other flói
sociations is that Chamæphytes are very conspicuous both in
physiognomy and covering. In this respect it approximates the
shrub mire. It is frequently difficult to distinguish in terms of
vegetation between the two. E. angustifolium, however, never ac-
quires the same prevalence in the mire as here in the flói. Perhaps
it would have been more proper to identify the sociation with Em-
petrum rather than Vaccinium, but according to the rule of per-
mitting the physiognomy to determine when frequency and cover-
mg are similar, Vaccinium prevails. It is also constantly dominant
m this sociation, but Empetrum is subject to greater fluctuations.
Among other species worth mentioning there is Carex vaginata,
which often occurs. Then there is C. nigra and Scirpus cæspitosus,
both of which appear in noticeable quantity in some of the analyses,
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