The Botany of Iceland - 01.12.1930, Page 185
SUMMARY.
1. By investigations on the quantitative distribution of the life-
lonns in the floras, from temperate to progressively arctic regions,
Raunkiær has shown that the chamæphyte percentage is subject
to a steady increase from southern towards northern regions. Current
conditions in the surrounding seas show an appreciable iníluence on
the course of the individual Ch biochores, a warm nortligoing cur-
rent causing a decrease of the Ch percentage, while a cold south-
going current causes an increase of the Ch percentage. This appears
plainly from conditions along the coasts of Greenland and Iceland.
2. If the Icelandic flora is divided into groups according to the
northern and southern limits of the species, 7 species groups will
result, distributed in 2 main groups. The 2 main groups represent
species with respectively a northern and a southern distribution. The
sub-groups within eacli main group difler from each other with re-
spect to their northern limit. If the biological spectra of tlie in-
dividual groups are examined, a continued increase of the Ch per-
centage from the species group with the most southerly distribution
to that with the most northerly distribution will be observed. If like-
wise the variation of the biological speclra and the species group
spectra in the flora lists of the separate parls of the country and
altitudinal zones is examined, the variation is the same in both
cases, but greatest in the case of the species groups. Species groups
and life-forms may tlius be regarded as indicators of environment
and may be made the basis of considerations on external factors
where these are unknown.
3. Iceland’s Ch percentage ranges it among the boreal hemi-
ccyptophyte-chamaephyte climates, the Ch percentage for the whole
country being 15.2. The 20 p. c. Ch biochore for the country as a
'vhole lies at a level of c. 300 m above the sea. Between this line
and the snow-line, which lies at a level of c. 1200 m, it is possible