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ŠUMARSKI LIST 7/1952 str. 16     <-- 16 -->        PDF


This article deals with measure´s for the improvement of forest production which

may be realized in a short tiime; for instance within 20 years.

These measures include:

1) Thinning and clearing. These measures wi!M not only increase the quality of
the principail crop but the whole return as well.

All lowland and hillside forests in ´Croatia are being thinned very intersirvely. It
is necessary to extend the thinning on areas that have not been thinned yet. These
are usually youlng and middleaged stands which, grew after the virgin-forests were
intensely harvested and where the forest railways were allmost the only means of
transport. At present these forests are closed and for that reason were left without
any siMcuIturail-tendiing. By enlarging the thinning-area n´t would! be possible to
produce a surplus of 200.000 m3 and the ´thinnings are estimated to approximately one
million cuib. met. a year.

Heavy thinning is recoromented. This is useful principally because of unfavorable
proportions of the age-elasses-the yield of the final felling Will comsideraibly decrease
but nevertheless it shall! be necessary to cut immature crops.

By -means oif heavy thinning we shall attain a more rapid dfametar growth of the
trees and a favorable preparation for felling according to the shelterwood method.
The principal means to develop forest production is to build a better network
of communications system and introduce various organisational measures.
2) In selection forests we should apply the lowest possible short felling-cycle in
order to increase the increment and improve the quality of the stands.
By applying the felling-cycle of 6-years ´the increment is at least lOVo greater
than that achieved by applying the felling-cycle of 20 years.

3) In high even-aged forests of principal species an average rotation ahould be
prescribed in order to insure the largest increment and the most favorable asortment,
while on the other hand in the same time the real proportion of the age-classes should
be taken into consideration as well as a certain continuity in harvesting of woods.
For oak a rotation of 120 is recommended; for beech 100, for the rest of the broad-
leaved species (ash, elm, hornbeam etc) 80 years, for soft-woods 60 years. According
to already executed fellings it has been estimated that the real overage rotation for
oak is 102, beech 92, for the rest of the biroadleaved species 84, and for softwood 56

Therefore it is recommended to prolong the real rotation but to reduce it in
relation to former regulations for state forests (oaik 140, beech 120 years). With average
oak rotation of 120 years it is best to fell! the stands that are 140—160 years of
age until the weaker stocked stands of poor quality with a large antermiixture of ash
and elm trees should be felled at an age of 80—120 years. The same proiceedure should
be camied out with beech-stands as well.

4) Waste-reduce. The waste of wood is about 22°/o. By improving the labor
methods and increasing the network of solid communications the waste reduced to
15c/o which would mean an increase in production to albout 350.000 m3 a year.

AW the measures foi the improvement of forest production can be executed «n
the greatest degree only when the forest exploataifcton is managed1 by the forestry.