Rit (Vísindafélag Íslendinga) - 01.06.1975, Side 28

mined by rough estimation, when it is not feasible to check it
throughout the year, and therefore the estimate may be questioned,
if the moisture content is measured in either unusually rainy or
unusually dry summers. I have on occasion made the distinctive
determination on the basis of vegetation, topography and mound
formation, when extraordinarily wet conditions during my observa-
tions made it unfeasible to rely on the level of the ground water
alone. Consequently the distinction between these vegetative covers
is not to be drawn as clearly as would have been desirable in many
instances.
Classification of vegetation
In the following chapters an attempt will he made to define and
describe the main sociations of the flói and other divisions of the
Icelandic mires. My vegetation analyses were made by means of
the Raunkjær method. Each analysis contains 10 sample plots mea-
suring 1/10 m2 each. Where there are no more sample plots avail-
able and often few analyses of each sociation, not all the species
of the sociation can be included in the tables. This, however, is not
as noticeable in the flói as in most other types of vegetation, for the
species in question are fewer and most of the sociations are clearly
defined.
The sociations are identified by the species which prevail in the
physiognomy and also in covering. Thus the most conspicuous spe-
cies are first counted and then the other concomitant species on the
basis of their abundance according to the same criterion.
Their points sum according to Raunkjær’s count does not indi-
cate this, but rather their frequency alone. Two species with the
identical points sum within the same sociation may constitute
astonishingly different proportions of the vegetation. One of these
species may characterize the vegetation cover and register cover-
ing at 5 on the Hult-Sernander Scale, whereas the other may be
discovered only upon closer scrutiny not having any substantial
cover. Perhaps I have not rated such constant species highly enough,
since they could be characteristic of the sociation although they
are not conspicuous.
I have accordingly divided the flói sociations into six main cate-
gories, which may be referred to as associations in the sense which
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