Arctic plant ecology: From tundra to polar desert in Svalbard - Unis

Taking all of Greenland into account taxa occurring both on Svalbard and Greenland
tend to show the same overall ecological amplitude regardless of low or high arctic
environment. However, further studies are necessary to verify this statement. As yet,
generalisations of ecological amplitudes of plant taxa for the entire Arctic should be
considered with care.
Ecological amplitudes of vascular plant species on Svalbard
The results show that the majority of the species over all pH ranges exhibit their main
distribution limit in bioclimatic zone A. Regarding pH amplitudes very few plants
(five species) seem to be able to grow at low pH (< 5.2) values. Most prefer medium
to high pH substrates (62 species). This reflects the substrate availability on Svalbard
with weakly acidic substrates (pH 5.2­7.0) covering the largest area.
Cerastium arcticum, Poa arctica, Saxifraga cespitosa ssp. cespitosa and Salix polaris
are truly widespread species with a wide ecological amplitude in terms of both pH and
temperature. In addition, they show a wide tolerance concerning total plant cover (10­
90%) and a medium range for disturbance and moisture (s. Appendix 1). Species
which are restricted to bioclimatic zone C or D and exhibit a narrow pH amplitude are
less widespread.
More than half of the species in each substrate group except the acidic and weakly
acidic substrate group are widespread on Svalbard. All three substrate types occur in
each bioclimatic zone on Svalbard. Thus the substrate type does not appear to limit
distribution of species on Svalbard.
Luzula confusa and Poa arctica, although widespread on the species distribution map
of Svalbard, received relatively low values in the district count per species. This may
be due to an underrepresentation of the taxa in the Svalbard database which served as
a basis for the district count.
Ecological amplitudes of a few selected species were compared to the vegetation type
map (Arnesen, personal communication), species distribution map and substrate map
of Svalbard (Arnesen, personal communication) to verify our findings. Our study
shows that Luzula confusa prefers substrates of low to medium pH. The substrate on
Nordaustlandet, where the Luzula confusa vegetation type is dominant, consists
mainly of acidic substrate types reflecting the species preferences. In addition, the
distribution map shows that Luzula confusa doesn’t occur in the area of alkaline
circumneutral substrates but is present on acidic and weakly acidic substrates. The
medium to high pH values which were recorded for Papaver dahlianum ssp. polare,
are congruent with its occurrence in the Papaver polar desert where partly alkaline
and weakly acidic substrates are dominant. The mesic Luzula nivalis vegetation type
of bioclimatic zone B relates to weakly acidic and alkaline substrates and the assigned
pH range of Luzula nivalis. The distribution of the Poa alpina snow beds corresponds
to a substrate higher in pH which is expressed in the species pH tolerance of medium
to high pH values. On the species distribution map, Papaver dahlianum ssp. polare,
Luzula nivalis and Poa alpina are mainly distributed in areas with weakly acidic to
alkaline circumneutral substrates matching their ecological pH amplitudes. The
Cassiope tetragona ssp. tetragona vegetation type, occurring on weakly acidic
substrates, is less well expressed in our data where a narrow pH range of high pH
values was recorded for C. tetragona ssp. tetragona. However, the species distribution
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