The Botany of Iceland - 01.12.1930, Qupperneq 132

VI. THE DISTRIBUTION OF SPECIES, SPECIES-
GROUPS, AND LIFE-FORMS IN THE FORMATIONS,
ARRANGED ACCORDING TO INCREASING PREVAL-
ENCE OF ONE AND THE SAME EXTERNAL FACTOR
In the two preceding chapters we liave treated in more detail a
series of Icelandic formations with respect to their environment
and their floristic and biological characteristics. A very important
part still remains to be treated, viz. a determinatión of the areas
covered by the individual species within the tracts examined.
The most obvious method of determination would be to map
the formations within the tracts examined, and determine their areas
on the basis hereof. But this work would involve too much time
and trouble if it were to be accomplished in a fairly reliable way.
A more practical method has been worked out by Thore Fries
in 1919. The mode of procedure in this method, “the synecological
line taxation method”, is as follows. A system of deflnite lines,
drawn according to more precise rules, is laid down, and the lengths
of line covering the respective formations, are then measured. If
the system of lines is correctly laid, that is to say, if the lines are
laid sufíiciently close together, the sum of the lengths of line cover-
ing a given formation will afford a measure for the area covered
by the formation within the tract examined, and the proportion of
the length of line covering a given formation to the total length of
the line system will correspond to the proportion of the area covered
by the formation to the total area of the tract examined. (Th. Fries,
1919, p. 8).
In my investigations of the Icelandic vegetation I did not em-
ploy Fries’s line taxation method, a fact which I have often
regretted during my elaboration of the material, but during inves-
ligations in Denmark I have often experienc.ed how practical tliis
method is compared witli the usual inapping of the formations of
an area. Tlius I have the same experience of the line taxation
method as has Thore Fries of Raunkiær’s circling method . . . .