The Botany of Iceland - 01.12.1930, Síða 148

H. M0LHOLM HANSEN
138
the result of the effect on the halla mýri of the warm
water in the winter.
The Distribution of the Species in the Scale of Moisture.
Table 27 shows the distribution of the species in the scale of
moisture respectively at Bjork, on Lýngdalsheiði, and on Arnarvatns-
heiði. A special column further shows the average values for these
three localilies.
The Lækjamót series has not been included in the table since
the mýri formations here differ in several respects from the above
mentioned, thus causing some deviations which are not due to the
conditions of moisture. On the whole, however, the distribution of
the species in the scale of moisture in the Lækjamot series coníirms
the relations stated below.
In order to facilitate a general view the species have been
grouped according as they occur with the greater frequencj' in the
lowland formations or in the highland formations, or witli equal
frequency in both. Wilhin each of these groups the species have
then been arranged with the least »moisture-loving« first and the
most »moisture-loving« last. Considerations of space have, however,
necessitated the exclusion of some more rarely occurring species.
Tlie figure marked against a given species in a column is the
average F.-percentage of the species in question for the zone of
moisture of the locality in question. Thus in the Elyna mo at Bjerk,
Festucá rubra has the frequency percentages 96, 96, 100, and 96
in the 4 localities there examined. The sum, 388, divided by the
number of the localities, 4, makes 97, which is the figure marked
against Festuca rubra in table 27, Bjork I.
If, next, we consider the distribution of the species in the scale
of moisture, it is an extremely variegated picture that meets the eye
both as regards quantitative distribution, tbat is to say, the average
distance of tlie individuals, and as regards the mode of distribution
in the scale. Some species show a low F.-percentage (i. e. a great
average distance between the individuals), others a high F.-percen-
tage (i. e. a small average distance between the individuals). Some
species occur only in a small number of moisture classes, others
in a larger number or in all classes. Some species only occur in
the dry classes, others only in the moderately moist, others again
only in the moist etc. But to whichever class or classes a