In subarctic ecosystems, plant growth is
mostly limited by nutrient availability and harsh
climate. Investigating how soil nutrient availability
controls the plant community composition may
therefore help to understand indirect effects of climate
change. The study was conducted in a long-term field
experiment on a subarctic-alpine fellfield dominated
by woody evergreen shrubs, bryophytes, and lichens.
To manipulate nutrient availability additions of NPK
fertilizer, labile C, and fungicide (benomyl) were
done in a fully factorial design, replicated in six
blocks. The treatments were run for 10 years, and the
aboveground plant biomass was harvested 4 and
16 years after initiating the experiment. In addition,
soil inorganic N and P concentration was analyzed the
same years. Increased nutrient availability (NPK
fertilizer) largely increased the biomass of graminoids
and unexpectedly of bryophytes, but not of other
vascular plant groups. Also, limitation of soil nutrient
availability caused by labile C addition decreased the
relative proportion of green shoots in evergreen
shrubs, although these were expected to cope better
with the nutrient limitation than the opportunistic
graminoids, which, by contrast, were unaffected.
Reduced fungal biomass due to benomyl addition
was accompanied by increased evergreen shrub and
clubmoss biomass. Taken together, the effects of
treatments were most pronounced 16 years after
initiation of the experiment, but despite changes in
biomass the overall plant community composition
was resistant to environmental changes.