Fróðskaparrit - 01.01.2002, Side 129

SOPPARÓT f FØROYSKUM FJALLAVØKSTRI
127
Statistic
The statistic is based upon a correlation
matrix, where all 102 plant species in all
532 plots are correlated using Microsoft
Exel. A Spearman’s rank-order corelation
is then performed on the factors, that seems
to have the best correlations. For the Spear-
man test, the SPSS package was used.
The plants are divided into groups after
what type of mycorrhiza they form, and
then the different types of mycorrhiza are
correlated to each other (Table 7). The most
signifícant results of correlations per-
formed directly on plants with a sum of fre-
quencies of at least 100, are presented in
Table 8.
Finally the different types of mycorrhiza
are correlated to nutrients (Table 10).
Discussion
The overall results suggests that the
Faroese vegetation is heavily dependent on
mycorrhiza.
The statistical results indicate that some
common arbuscular mycorrhizal plant
Type of mycorrhiza Type of mycorrhiza cor- lation P(rs)
Arbuscular Ecto -0.005 0.905
Arbuscular Ericoid 0.358 0.000
Arbuscular Orchid 0.200 0.000
Arbuscular Non-mycorrhizal -0.143 0.001
Ecto Ericoid -0.373 0.000
Ecto Orchid -0.229 0.000
Ecto Non-mycorrhizal 0.096 0.027
Ericoid Orchid 0.240 0.000
Ericoid Non-mycorrhizal -0.148 0.001
Orchid Non-mycorrhizal -0.028 0.525
Table 7. The different mycorrhizas correlated.
Negative correlations could indicate that these
mycorrhizal associations do not coexist.
species are connected to ectomycorrhizal
plant species. For example are Festuca
rubra and F. vivipara both positively corre-
lated with Polygonum viviparum, while
Agrostis canina is positively correlated to
both Polygonum viviparum and Salix
herbacea (Tabie 8).
It is known from the literature that some
plant species are able to associate with dif-
ferent types of mycorrhiza. In the checklist
of mycorrhiza (Harley and Harley, 1987)
Polygonum viviparum has a single arbuscu-
lar record, but several ectomycorrhizal
records. Also Silene acaulis is able to sup-
port more than one form of mycorrhiza; it is
able to form both arbuscular and ectomyc-
orrhiza. According to Harley and Harley
(1987) S. acaulis is more likely to be arbus-
cular, and has therefore been considered as
only arbuscular mycorrhizal in this dataset.
Arbuscular mycorrhizal plant species
can be divided into two groups, coexisting
with either ericoid mycoiThiza or ectomyc-
orrhiza. Arbuscular mycorrhizal plants
which typically coexist with ericoid mycor-
rhizal plants are Nardus stricta and Poten-
tilla erecta (Table 8).
Arbuscular mycorrhizal plant species to-
gether with ectomycorrhizal species are
such as Deschampsia flexuosa and Festuca
rubra (Table 8).
One atypical plant species in this context
seems to be Thymus praecox, which man-
ages to coexist with both the ectomycor-
rhizal Polygonum viviparum (r = 0.14, p =
0.001) and the two ericoid mycorrhizal
plants Vaccinium myrtillus (r = 0.25, p =
0.000) and Empetrum nigrum (r = 0.24, p =
0.000). There is a negative correlation with