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ŠUMARSKI LIST 11-12/1999 str. 13     <-- 13 -->        PDF

IX Kajba, S. Bogdan. P. Viataric: USPIJEVANJE Kl.ONOVA BIJELE VRBE (Salix alba L.) U MJLšOV. KULTURI... Šumarski list br. II I 2, (XXIII (1999), 523-53 1


tion age the influence of the black alder on the white willow clone production
in terms of positive modifications is significant. Besides, by the black alder
presence the amount of weed vegetation is reduced. From the eighth to the
tenth year of the plantation age, the black alder influence on the white willow
clone growing is very pronounced in terms of negative modifications. This fact
is explained by a very keen white willow — black alder competition, resulting in
the reduction of their tree crowns that causes the decrease of increment. At the
plantation age of 10 - 13, the number of clones with positive modifications is
reduced considerably, while at the age of 15 and 17 years this influence is
completely lost. The generally valid rule is that with plantation ageing the
number of clones with positive modifications reduces.


The arborescent willow clones recommendable for growing in association
with the black alder on its habitats in Podravina have been selected, namely:
V161, MB 368, MAđ40, V160, BrlBB, S86, Rep2, V99, 11/1 and V093.


To improve the white willow growing in the mixed cultures with the black


alder, it is suggested that such cultures are established with a 4 x 4 m spacing
for the white willow planting and that in every second row the seedlings are
planted at a spacing of 4 x 2 m. The black alder would be planted at a 4x1,5 m
spacing. The first white willow felling will be done at the plantation age of
eight years, and this in the rows with the planting at a 4 x 2 m spacing. The
planting spacing of the culture then would be 8x4 m for the white willow and
4 x 1,5 mfor the black alder. At the plantation age of 15 to 20 years, the felling
of all other white willow trees would be done. In this way, after the first felling
an intermediate yield of the white willow pulp wood be ensured and sufficient
light for an undisturbed growth of the black alder would be provided. By using
the high current white willow increment from the eight to the fifteenth or twentieth
year, the second intermediate yield in logs for the white willow could be
achieved, and after the white willow felling the free development of the black
alder as the main culture would be made possible.


Key words: mixed plantations, Salix alba clones, Alnus glutinosa, modification,
Nfix a tion