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ŠUMARSKI LIST 3-4/2010 str. 29     <-- 29 -->        PDF

M. Z. Ostrogović, K. Sever, I. Anić: UTJECAJ SVJETLANAPRIRODNO POMLAĐIVANJE HRASTA... Šumarski list br. 3–4, CXXXIV (2010), 115-123
SUMMARY: In a forest park Maksimir, in a mixed forest stand of Pedunculate
Oak and Common Hornbeam (Carpino betuli-Quercetum roboris /Anić
1959/ Rauš 1969), influence of light conditions on number and quality of
young oak growth was investigated. Experimental plot covered two regeneration
gaps and the space between, including the trees in a different stage of development
(seedlings, saplings and young trees). Measurements were taken in
the winter 2006 and spring 2007 in a single plot within the stand. The plot was
divided in 105 sub-plots of 1.5 m x 1.5 m and on each sub-plot height (cm),
tree length (cm), ground level diameter (mm) and last five height increments
(cm) were measured. Parallel to the measurement, evaluation of stem quality,
crown form and tree health state was conducted. Spatial distribution of old
grown trees at the plot area, together with crown projections, was recorded. At
each sub-plot a hemispherical photograph was taken. Average annual relative
values of diffuse and direct light for different development stages of Pedunculate
Oak were determined. Depending on the values of diffuse and direct light,
four microsites (marked: A – D) with different light conditions were defined.

Results indicate that natural regeneration in naturally occurring gaps
could be considered successful. Average number of trees per square meter was

8.3. Species composition of naturally occurring young trees in the gap indicates
a continuation of the same forest community, namely mixed forest stand of
Pedunculate Oak and Common Hornbeam with a smaller share of Wild
Cherry (Prunus aviumL.), Hedge Maple (Acer campestreL.), Norway Maple
(A.platanoidesL.) and Lime (Tiliasp.). Mixed forest stands are of great biological
and ecological value, but also attractive to the park visitors. Maintaining
them and their stability is a main management goal in this forest park.
However, in naturally occurring gaps in the absence of silvicultural treatments
the quality of young trees is questionable. High density of young growth
at our plot resulted with high tree slenderness coefficient of 97,7. Share of deformed
tree stems was significant (30.3 %), as well as share of badly developed
tree crowns (44.3 %). Great abundance of weed vegetation was recorded
and can be attributed to the lack of silvicultural treatments during regeneration.
Chi-square test showed statistically significant dependence of number of
young oak growth in different development stages with respect to the light
conditions at microsite. Lower values of direct and diffuse light (microsite C)
correspond with great number of oak seedlings. Surviving of oak seedling in
low light conditions confirms the fact that in first few years oak is shade tolerant.
However, great abundance of oak saplings at microsites A (lower values
of direct and higher values of diffuse light) and D (higher values of direct and
lower values of diffuse light) indicates that oak, when it arrives to the stage of
saplings, favours higher light conditions. This is further corroborated at microsite
B (with high values of direct and diffuse light) where young oak trees
were most abundant. Quality of oak saplings and young trees was better at microsite
B. Young oak trees grown in high light conditions obtained greater
height increment and stem verticality. High positive correlation is obtained
between Pedunculate Oak average height increment and average values of direct
light (r = 0,5809).
Key words: regeneration gap, development stages, direct and diffuse
light, quality of young Pedunculate Oak growth.