The Botany of Iceland - 01.12.1930, Blaðsíða 133

STUDIES ON THE VEGETATION OF ICELAND
123
’the niethod, in my opinion, constitutes an ingenious and satisfactory
solution of the problem.” (Th. Fries, 1919, p. 4).
I can likewise fully support the author when he goes on to say,
“Raunkiær’s circling method and the synecological line taxation
method complete each other. By the former we obtain exact
knowledge of the nature of the units, by the latter of their area and
distribution. Synecological plant geography should be able to make
great progress in exactitude by these two methods. Synecology now
need no more rank last in this respect among the various branches
°f botany, on the contrary, it should soou be able to take up its
position as one of the first.”
However, the results which these two methods will be able to
produce, viz. an exact description of the plant series of the face of
the earth, only constitute one aspect of plant geograpliy, the geogra-
phical aspect. F’or such a description is primarily of importance
in its bearing on geography. The botanical aspect proper will only
appear when, in addition, we investigate the external factors which
determine the distribution of the individual biological or syste-
matic units.
If we follow the ordinary scientific method of investigating the
facts in connection with a given unit by varying only one external
factor at a time and as far as possible keeping all the other factors
constant, this means, in the case of the doctrine of formations, that
"’e must primarily examine the distribution of the indi-
vidual species within the formations, arranged according
to increasing prevalence of one and the same external
factor. The resulting facts mav then be made the basis of inore
detailed ecological considerations.
In the jiresent chapter we liave examined the distribution of a
series of Icelandíc species partly in relation to the Icelandic scale
of moisture, partly in relation to the scale of snow-covering. The
material employed is tlie same which was utilised for the formation
statistics of the two preceding chapters. On the basis of this ma-
terial we have further examined the distribution of Raunkiær’s
life-forms and the species groups in relation to the above-mentioned
two scales.
The Scale of Moisture.
Under the treatment of the formations in the localities examined
the degree of moisture has been more precisely described.