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ŠUMARSKI LIST 11-12/2009 str. 8     <-- 8 -->        PDF

M. Čater, P. Simončič: PHOTOSYNTHETIC RESPONSE OF YOUNG BEECH (Fagus Sylvatica L.) ... Šumarski list br. 11–12, CXXXIII (2009), 569-576

dimension. Evident changes in distribution of plants and

species diversity consequently affect primary producti

vity (Callaghan etal. 2004).

Several key questions about the future response of
beech to expected changes such as temperature increase,
redistribution of precipitation and increase of atmospheric
CO concentration remain open and without answers.
Quotations in literature and research results are in most
cases unclear and sometimes even contradictory (Po or ter
1998,Lloyd andFarquhar 1996). Photosynthe
sis, the first estimate of net productivity could be
measured as the response of plants to different light intensity
or the response to different concentration of CO


which is entering the system in the controlled environment.
In spite of good understanding of processes of carbon
dynamics at leaf level in a changed CO


environment, it is difficult to make a prognosis of the fu

ture response of the whole plant, also because of the

short time interval of observations and numerous possible
interactions that have not yet been recognized.According
toBatič(2007) most changes by the increased
amount of atmospheric CO could be expected for C3


plants at the beginning of saturation curves, especially
for the plants that grow in reduced or minimal light conditions,
close to compensation point.Wemay therefore
expect most changes in shade tolerant species.

The research goal was to define range of photosynthetic
response in young beech in dependence of light
intensity and different concentration of CO between


three canopy conditions (shelter, forest edge and gap)
on different forest sites.

MATERIALAND METHODS – Materijali i metode

Research was performed on 10–15 year old beech
trees at five selected natural forest stands: at Kladje and
Brička in the Pohorje area, atVrhovo and the karstic-

Table 1 Research plots characteristics

Tablica 1.Značajkepokusnih ploha

dinaric area in Kočevski Rog –at Snežna jama (managed
forest) and Rajhenav (virgin forest) (Table 1).

air T
Prosječna godišnja
Tip tla
Growing stock
Drvna zaliha
Brička 1093 46o28’40’’ 15o15’40’ 1190 9,1 Dystric Cambisol 477
Kladje 1308 46o28’48’’ 15o23’24’’ 1066 9,2 Dystric Cambisol 390
Vrhovo 273 45o48’25’’ 15o18’11’’ 1138 9,4 Acric Luvisol 479
Sn. jama 875 45o39’15’’ 15o01’40’’ 1330 8,3 Rendzic Leptosol 612
Rajhenav 865 45o39’36’’ 15o03’36’’ 1330 8,3 Rendzic Leptosol 992

Both Brička and Kladje belong to the acidophilous
beech forest type Luzulo albidae-Fagetum (Urbančič
and Kutnar 2006) while Snežna jama and Rajhenav
belong to dinaric silver fir and beech forest type Omphalodo-
Fagetum (Kutnar andUrbančič2008).

At each location a research plot was established
100x100m in size, reaching from complete closure to
open sky conditions on all plots with little or no exposure.
The gradient of natural light conditions was obtained
by selecting young trees under a range of canopy
openness. On each fenced plot, for 24 young beech
trees in comparable light-intensity conditions, their potential
light environment was estimated with hemispherical
photos (Anonymous 2003). Fine tuning was
applied after pilot analysis, so that the light conditions
on all plots were comparable.The parameter used for
evaluation of light conditions was the indirect site factor
(ISF) (Wagner 1994), which is the relative proportion
of diffuse light intensity above a defined plant
compared to open/gap conditions, (without shading) in
percentage (%). Photos were taken with a digital Nikon
Coolpix 990 and calibrated fish-eye lens and analyzed
withWinScanopy software. In the process of hemispherical
photo analysis the vegetation period was defined
for each plot group separately; for the diffuse light
distribution a “Standard overcast sky” (SOC) model
was applied. For the calculation within the vegetation
period, the sun’s position was specified every ten (10)
minutes.The solar constant was defined as 1370W/m2,

0.6for atmospheric transmissivity and 0.15 for the proportion
of diffuse radiation compared to calculated direct
potential radiation.According to light conditions
three groups were defined: stand conditions (ISF<20),
edge (20the sheltering effect of a mature stand (ISF>25). Height
of trees on plots ranged from 40 - 70 cm under stand
conditions, from 70–110 cm under edge conditions and
from 110–220 cm in open area conditions. In each
group, four trees were randomly selected for measurement
of photosynthesis. In the same leaves nitrogen


concentration [mg/cm] was determined to compare

macronutrient status in different light categories (Leco

CNS-2000 analyzer) (Anonymous,2007).