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ŠUMARSKI LIST 13/2005 str. 153     <-- 153 -->        PDF

S. Kucbel: THE STRUCTURE AND NATURAL REGENERATION OF A SUBALPINE SPRUCE KOREST ... Šumarski list- SUPLEMENT (2005). 144-153
15-20 years have focused the attention on the problems
of high-elevation forests recently. The immission
impact and extreme weather situations caused by
global climatic changes have been probably the crucial
factors which have activated the process of the breakdown.
The research results (Gubka 1998, 1999) as
well as the experiences of practical foresters have
shown, beside the mentioned factors, the unstable
stand structure remains the key problem of high-elevation
forests. This is the result of absent silvicultural regulation
and it causes the low resistance to the disturbances
and high probability of calamity breakdown.


Solution of the problems of silvicultural interventions
in high-elevation forests requires to know and to
consider their specifics to the forests in lower altitudes.
If we want to understand the natural dynamics of high-
elevation forest we can use the knowledge obtained
from the long-term research of primeval forests in the
7th forest vegetation stage. Studying the life cycle of
the Norway spruce primeval forests some natural tendencies
with negative impact on the stability of high-
elevation forest have been found out (Korpel ´ 1989,
Schmidt-Vogt 1991, Leibundgut 1993). These
are mainly the tendency to develop a less stable mono-
layered structure with horizontal canopy during the
long-time optimum stage, the stagnation of regeneration
processes and the proneness to the calamity breakdown
which causes the loss of required structure for a
relatively long period. On the basis of these findings
the most authors (Leibundgut 1978, Korpel´
1980, Mayer-Ott 1991, Schmidt-Vogt 1993)
tend to think a Norway spruce natural forest doesn´t


have, especially on the convenient sites, the permanent
ability to fulfil all protective functions. A high-elevation
forest with optimal stand structure which is the result
of intentional silvicultural interventions is more
stable than a Norway spruce primeval forest and thus
the pointed silvicultural regulations seem to be necessary
for the permanent protective effect.


For the forest with permanent protective effect in
the high altitudes the permanent presence of the tree individuals
on the site, stability of single trees as well as
of the whole stand and gradual natural regeneration
should be characteristic. This needs satisfies a stable,
natural regenerating, uneven-aged and multi-layered
forest at most. Time unlimited durability of structure
and permanent regeneration are in general the attributes
of a selection forest. Therefor most authors
(Kuoch 1972, Trepp 1981, Bischoff 1987, Ott
1988, Frehner 1989, Ott et al. 1997) consider so-
called mountain selection forest ("Gcbirgsplenterwald")
the ideal pattern of a Norway spruce forest in
the high-altitude sites.


Naturally long-time process of natural renewal is
one of the specifics of the high-elevation forest. The
permanent natural regeneration without the limitation
of protective effects, which secures the change of forest
generations, is the crucial problem in the high-altitude
forest. Ott (1988) consider the stand renewal "the
weak link in the chain of forest dynamics" in the forest
growing near the tree limit. According to Trepp
(1961) the silvicultural regulations fulfil their purpose
in the high-elevation forests only in the case they are
able to secure their natural renewal.


METHODS


The research was conducted near Korytnica in northern
Slovakia. On the locality Prasivä in west part of
Nizke Tatry Mountains three permanent research plots
(PRP) in a stand with protective function were established.
The plots were placed in the parts where the stand
structure was most differentiated so that it was approximating
an ideal structure of the mountain forest. Every
plot had a dimension 30 x 30 m and included a transect
with the width of 10 m. On the research plots particular
stand characteristics as well as the state of natural
regeneration on the transect were acquired and on the
basis of them the model stand structure was approximately
quantified.


The research plots were situated on a west slope in
the average altitude 1,300 m a.s.l., the slope ranged
from 50 to 70 %. The slope is covered with pure Norway
spruce (Picea abies (L.) Karst.) stand with rare
presence of rowan (Sorbus aucuparia L.) and mountain
pine (Pinus mugo Turra). According to the forest typology
three forest communities could be found


Sorbeto-Piceetum (60 %), Fagetum abietino-piceosum
(30 %) and Mughetum acidofilum (10 %). For this
compartment the forest management plan states the
average age 180 years and average crown canopy 0.7.


On the PRP the set of following parameters was
measured for every individual: tree species, dbh (over
1 cm), tree class (according to the top height - upper,
middle and lower layer), defoliation (visual estimation
of the loss of assimilation organs in 10 %). In addition
to this data next variables were measured on the transect:
height, height where the crown development begins,
crown radius (in four directions) and the position
of the stem on the transect (x, y - coordinates).


On every PRP coarse woody debris was registered
as well and the length, diameter in the middle of length
and the decomposition grade (1 - recently fallen,
sound, 2 - partly rotted, tree species can be determined,
3 - advanced decay, tree species cannot be determined)
of each log was measured.