Rit (Vísindafélag Íslendinga) - 01.06.1975, Blaðsíða 151

area which could be a mire tract, dried out due to the effect of
blown sand, with resultant favourahle conditions for the jaðar
vegetation. Analysis 7, Hrútafell, Rang. is made on a fertile glacial
moraine where the sociation covers an extensive area. In many
places there occur red patches of Lychnis flos cuculi which is a
characteristic species in those parts. It is notable, however, especial-
ly in the southem part of the country, how many herbaceous plants
occur in this sociation, e.g. Galium boreale, Filipendula ulmaria,
Geum rivale and others. Analysis 10, Sauðhúsvöllur, Rang., where
the conditions resemble 7, but the ground is somewhat damper
which may be the reason for the ahsence of E. palustre. I have
noticed in other areas that its growth decreases where the jaðar
becomes damper. Analysis 8, Stafholtsey, Rorgarfjörður, in an old,
dried out river bed, through which Hvítá used to flow. A large
horder area there resembles that of 7 and 10. Rhacomitrium is
conspicuous. J. balticus is sparse, but Graminea are noticeable in
covering.
87. J. balticus — Kobresia myosuroides sociation
(Tab. XXI í)
This sociation is much less common than sociation 86. It probab-
ly occurs, however, in various places in the eastem part of the
country, but I have not recorded observations of it from elsewhere.
The only analysis presented here is made at Hof in Vopnafjörður
on a relatively dry river bank and it forms a transition to Kobresia
heath in more elevated areas. I also have some observations from
Fljótsdalshérað, from the area between Hafursá and Mjóanes,
where fairly extensive Kobresia heath tracts are encountered, in-
terspersed with depressions where the soil is moister. J. balticus
becomes a dominant species in the moister areas as the growth of
Kobresia decreases which is manifested by its almost total disap-
pearance from the physiognomy. This J. balticus sociation is clear-
ly distinguished from its surroundings. The area as a whole might
be regarded as a mosaic of these two sociations, K. myosuroides
heath and J. balticus — K. myosuroides jaðar. In the deepest de-
pressions gramineous plants, such as Anthoxanthum odoratum,
151