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ŠUMARSKI LIST 13/2005 str. 30     <-- 30 -->        PDF

S. Malić, I. Anić. M. Oršanić: SILVICULTURAL TREATMENTS AIMED AT IMPROVING Till: ANTI-EROSION ... Šumarski list - SUPI.FMF.NT (2005). 17-30
aspect, the selection structure is desirable in all kinds
of forest stands. However, the problem is that regular
selection management can achieve the selection structure
only in those forests in which the principal tree
species is silver fir.


A selection forest is mistakenly perceived by some
foresters as the "most natural" forest, whose appearance
is the closest to the virgin forest. However, it should
be borne in mind that the selection stage of a virgin forest
is only one of the periods in its life cycle. A selection
forest cannot be identified with a virgin forest,
because the former is the product of natural and selection
management. In this sense, it should be stressed
that a selection forest is a natural forest because it originates
from natural regeneration, but its selection
structure is of artificial character. This structure can
only be permanently maintained with selection management
and selection cuts as an integral part of this management.
Therefore, a selection forest is a commercial
forest form which is gradually lost if the forest is
excluded from regular selection management (Matić
et al. 2001, 1997).


The selection forest management was developed
and introduced for fear of the disappearance of forests
and of the consequences of primitive selection cutting,
clearcutting and disorganized forest management two
and a half centuries ago. Since selection forests generally
inhabit mountainous areas (range of silver fir), the
fear of erosions and avalanches, as well as the problems
with water supply highlighted the issue of management
with such forests.


The beech-fir selection forests in the Croatian part
of the Dinara chain were selectively cut, but also selectively
managed in an organized way as early as the
mid-18th century. The Croatian forestry experts who
advocated the selection management method and gave
outstanding professional and scientific contributions to
their improvement include A. Borošić, Đ. Nenadić,
A. Petračić,A. Kern,M.Tordony,V. Dojko
vie, A. Jovanovac, J. Majnarić, Ž. Miletić,
S. Šurić, M. Markić, S. Frančišković, D.
K1 e p a c, and many others.


Selection management involves the pennanent maintenance
of a normal growing stock distributed in a
selection structure. This is achieved with selection silvicultural
treatments which simultaneously tend, regenerate,
shape and sustain the selection structure, as
well as harvest mature trees and trees that need to be
harvested for different reasons. Selection management
entails a systematic, planned application of silvicultural
treatments in a selection stand. A part of this kind of
management is selection cutting.


The goal of silvicultural treatments is to form a selection
stand with an optimal structure, whose composi


tion mix will contain species with the most valuable and
the highest increment. Such a stand should make maximal
use of the soil´s production ability and at the same
time put forth abundant natural young growth. Management
in a selection forest comprises two groups of silvicultural
treatments:


a tending the young generation (trees and groups of
young plants and young stands)


b selecting, which consists of thinning trees and
groups of trees in the sapling, pole and prop stages,
as well as harvesting mature trees.


All the treatments in a selection forest are concentrated
in time and space, and form an indelible whole.
Should one of the above activities be absent, the structure
ofa selection stand will be disturbed, which in turn
reflects on the increment, regeneration and stability. It
can be concluded that the primary task of the selection
stand management consists of forming and maintaining
the selection structure. Only by doing this will
continuous natural regeneration be ensured as an important
prerequisite for the productivity and stability of
selection fir-beech stands.


The current selection forests infrequently manifest
changes that cause problems in selection management:
a) fir regenerates poorly or not at all
b) in some areas beech regenerates and expands aggressively
at the expense of fir
c) the growing stock in a stand decreases or increases
in relation to the normal model
d) the volume distribution by diameter classes is disturbed
e) the tree distribution by stand layers is disturbed
f) the increment is reduced, the largest trees age, physiologically
weaken and decline
g) cutting intensities are poor and differ from the realistic
possibilities
h) climatic and other changes in the environment of
selection forests cause dieback


i) the stand microclimate changes due to the cutting of
trees for the needs of motorways, gas pipes, transmission
lines and similar. This leads to dieback
and death of firs in all developmental stages


j) the routes of infrastructural facilities are planned
without consulting forestry experts, which causes
unnecessary dieback and devastation in the stand
and in the environment.