Dendroecological
analysis of the influence of strong winds and snow accumulation
on the growth of trees at the treeline in Vitosha Mountain,
Bulgaria
Momchil Panayotov,
Steffan Yurukov
University of Forestry, Sofia, Bulgaria
Correspondent e-mail: panayotov.m@ltu.bg
Abstract:
As in other parts of Europe, the treeline position in
the Bulgarian mountains has been affected by human action
in the past. In certain regions like the highest parts
of Vitosha Mountain overuse and fires have destroyed a
big part of the coniferous forests. In the 40-s of the
20-th century their restoration has been started by afforestations.
The forest authorities have taken the decision to use
tree species that were found elsewhere at the Bulgarian
subalpine forests - Macedonian pine (Pinus peuce Griseb.),
Bosnian pine (Pinus heldreichii Christ), Norway spruce
(Picea abies Karst.), Scots pine (Pinus sylvestris L.)
and the shrub form of Mountain pine (Pinus mugo Turra
ssp. mugo).
At the present moment the state of the trees from those
species allows the studying of the differences in their
resistibility to limiting factors at the treeline. Since
the afforestations in Vitosha Mountain have been made
below the potential thermal treeline, the most important
limiting factors here are the influence of strong winds
and accumulation of big quantities of snow due to wind
transportation.
Tree test sites have been chosen in Pinus peuce forests
with the aim to collect samples for dendroecological analysis.
The sites have been separated in two categories - affected
by strong winds and accumulation of big quantities of
snow and unaffected.
At the affected sites trees have been separated in categories
according to their stem and crown state.
By the means of dendroecological techniques have been
compared the growth of trees in affected and unaffected
sites, the years in which trees were damaged and the reactions
in the wood after such events.
The results from the analysis show that major impact on
growth of the trees in the region have stem deformations
and damages, caused by accumulation of big quantities
of snow and rhyme. Strong winds occasionally break the
last several years of vertical increment of the trees,
which are situated at the borders of the forest stands.
Trees with broken tops do not show serious decrease in
radial growth.
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