Rit (Vísindafélag Íslendinga) - 01.06.1975, Síða 19

found in dry soil in lowlying areas, but it occui's also with equal
freQuency in mýri tracts and in dry soil in highland areas. Char-
acter species and dominant species in individual associations are
Carex Lyngbyei and Scirpus cæspitosus, both of which are closely
associated with topographic mires. Among other mire plants we
roight mention Menyanthes trifoliata, Comarum palustre, Calamag-
rostis neglecta and Viola palustris, but these will be referred to in
dealing with the different types of soil.
Common species in certain mire associations and often dominants
in physiognomy and covering, but also dominants in other associa-
tions and actually belonging to dry soil species are: Equisetum
palustre, Betula nana, Vaccinimn uliginostun, Salix glauca and the
Graminea, Deschampsia cæspitosa and Nardus stricta. But in the
öiire sociations, where these species are dominants, there are always
so many pure mire species that they separate themselves in terms
°f vegetation from the dry soil sociations, and furthermore their
topography is the same as that of the mire. But generally the mire
as a whole is sharply distinguished with respect to vegetation from
the dry soil growth, and it is no less topographical that the latter.
When the mire tracts are mound patterned, there is usually some
difference between vegetation on the mounds and that of the hol-
lows. Mosses are richer in species and more dense in the mounds
and there more species of dry soil convene. Sometimes this vegeta-
tion difference is so great that it resembles the mosaic of two so-
ciations. I believe, however, that it is not justifiable to speak of two
sociations in this instance, as many botanists want to do, and this
’WlU be discussed later. I wholeheartedly support de Rietz statement
(1949, p. 286), where he holds that, despite differences in vegetation
°n mounds and in hollows, they both have so much in common,
e-g. microflora and formation, that they are not separable. Internal
celationships between the sociations of mounds and hollows are
öiuch closer than the relationship of either one to the other socia-
tions with which they have often been classified.
19