Sammendrag
Mountain vegetation is often considered highly
sensitive to climate and land-use changes due to steep
environmental gradients determining local plant species
composition. In this study we present plant species compositional
shifts in the Tatra Mts over the past 90 years
and discuss the potential drivers of the changes observed.
Using historical vegetation studies of the region from
1927, we resurveyed 76 vegetation plots, recording the
vascular flora of each plot using the same methodology as
in the original survey. We used an indirect method to
quantify plant species compositional shifts and to indicate
which environmental gradients could be responsible for
these shifts: by calculating shifts in estimated species
optima as reflected in shifts in the ecological indicator
values of co-occurring species. To find shifts in species
composition, focusing on each vegetation type separately,
we used ordination (DCA). The species optimum
changed significantly for at least one of the tested environmental
gradients for 26 of the 95 plant species tested;
most of these species changed in terms of the moisture
indicator value. We found that the strongest shifts in
species composition were in mylonite grassland, snowbed
and hygrophilous tall herb communities. Changes in precipitation
and increase in temperature were found to most
likely drive compositional shifts in vegetation resurveyed.
It is likely that the combined effect of climate change and
cessation of sheep grazing has driven a species composition
shift in granite grasslands communities.
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