Elek, László

Gáspár, Angéla

Koncz, Péter

Lakatos, Gyula

Mészáros, Ilona

Oláh, Viktor

Acta Biologica Szegediensis

English

University of Debrecen Electronic Archive

Volume 49(1-2):149-150, 2005
Acta Biologica Szegediensis
http://www.sci.u-szeged.hu/ABS
1Department of Botany, University of Debrecen, Debrecen, Hungary, 2Deptartment of Applied Ecology, University of 
Debrecen, Debrecen, Hungary
Péter Koncz1, Angéla Gáspár1, Viktor Oláh1, László Elek1, Gyula Lakatos2, Ilona Mészáros1*
ABSTRACT                        In this study the variability of leaf growth traits was investigated within the canopy 
of the two dominant tree species of  Quercetum petraeae-cerris forest community, covering 30 
% of the present forested area in Hungary. The investigation were performed in the “Sikfôkut 
Project” LTER site (Jakucs 1985). We compared the present leaf growth traits of species with 
those reported by Virágh (1985)  for years of 1973-1975 before the decline of sessile oak in the 
site. After bud break leaves of the two canopy layers exhibited different rate in the increase of 
leaf area (La) and leaf  mass (Lm). In spring shade leaves showed more intense increase in leaf 
area than in leaf mass. This resulted in a transitional large reduction of SLM in the shade leaves. 
In case of sessile oak the full leaf size was achieved within the same period in 2003 and 2004 
but the area of mature leaves were larger in both canopy layers in 2004 than in 2003. In case of 
sessile oak the area of mature leaves in growing seasons of 2003 and 2004 increased significantly 
as compared to the period before the forest decline (Virágh 1985). In the upper canopy layer 
of Austrian oak the leaf area and leaf mass did not differ significantly from those reported for 
the period before the forest decline. In the lower layer of the canopy, however, the increase of 
leaf area was observed but the leaf mass exhibited similar values. In 2004 the loss of leaf  area in 
the sun layer was 17% and in the shade layer 6 % as a consequnce of photophagous damages. 
In case of Austrian oak the loss of leaf area was smaller and amounted only to 1-5%.
Acta Biol Szeged 49(1-2):149-150 (2005)
KEY WORDS
sessile oak
Austrian oak
leaf growth
specific leaf mass
realtive leaf growth rate
*Corresponding author. E-mail: immeszaros@tigris.klte.hu
149
Variability of leaf growth characteristics in the canopy of 
sessile oak and Austrian oak
Proceedings of the 8th Hungarian Congress on Plant Physiology
and the 6th Hungarian Conference on Photosynthesis, 2005
Function of forests, the most complex terrestrial ecosystems, 
primarily depends on the organic matter production taking 
place in the canopy of trees. The efficiency of organic matter 
production is influenced by many plant and environmental 
factors among which the area and mass relations of as-
similating leaves are determinant. During the development 
leaves of trees are going through a series of functional and 
morphological specialization processes  and in the meantime 
they are forced to maintain their physiological balance and to 
adjust  the spatial and temporal fluctuations of environmental 
factors. Beside these the fine differences and fluctuations in 
the light and temperature conditons due to the place of leaves 
within the tree canopy influence the growth parameters and 
the whole physiology of leaves. As a consequence leaves in 
the upper and outside surface of the tree canopy (sun layer, 
sun leaves) exhibit distinct anatomical, morphological and 
physiological traits from those developing in the the inside 
of canopy (shade layer, and shade leaves). Sun and shade 
leaves have different significances in the overall physiology 
of the tree (Kozlowski 1971; Roderick 1982; Ülo and Kalevi 
1994).
In this study we investigated the variability of leaf growth 
traits within the canopy of the two dominant tree species of 
Quercetum petraeae-cerris forest community, covering 30% 
of the present forested area in Hungary. The investigation 
were performed in the Sikfôkut Project long-term ecologi-
cal research site (LTER; Jakucs 1985). The influence of the 
changes in stand structure due to the decline of sessile oak 
appeared nationwide in the 80 ies (Mészáros et al. 1993) on 
the alteration of leaf growth were evaluated by comparing 
our results with those reported by Virágh (1985)  for years of 
1973-1975. The influence of phytophagous insects on the leaf 
growth traits of the two species was also studied.   
Materials and Methods
The “Sikfôkut Project” experimental site is situated at 320-
340 m a.s.l. in the Bükk mountains in the North-Hungarian 
Central Range. The geographic, climatic, soil conditions  and 
vegetation  of the site and the adjacent area are described 
by Jakucs (1985). The site is covered by a 85-90 years old 
stand of the climate-zonal sessile oak-Austrian oak com-
munity (Quercetum petraeae-cerris). The decline of sessile 
oak occurred in Europe in the 80 ies seriously influenced the 
structure and compostion of the forest stand of the site (Jakucs 
et al. 1986; Mészáros et al. 1993). Opening of canopy layer 
and formation of canopy gaps as a concomitant with the 60% 
decline of sessile oak influenced the microclimatic condi-
tions and the dominance relations of the vegetation layers 
(Mészáros et al. 1993).  
The investigations were prformed in the growing seasons 
of 2003 and 2004. The two years were completely different 
150
in weather conditons especially in the distribution and the 
amount of rainfall. Spring was very dry in 2003 and wet in 
2004. Leaves were collected regularly from the upper and 
lower canopy layers of 3 trees of sessile oak and Austrian 
oak from the metorological tower from the bud break until 
the end of summer. Leaves were samled in three shoots of 
every layer. The leaf area (La) was determined by means of 
AeaScope 5 v1 leaf area measuring system developed in the 
Department of Botany, Debrecen University. Parallel to the La 
measurements, leaf length, leaf width and damaged leaf area 
were also determined. Dry mass of individual leaves (Lm) 
were weighted after drying at 85°C for 48 hours. Specific leaf 
mass (SLM, g dm-2) was calculated as the ratio of Lm to La. 
Relative Leaf mass Growth Rate (RLmGR) was calculated 
as (ln Lm
2
-ln Lm
1
)/(t
2
-
 
t
1
) (g g-1 day-1)  
Results and Discussion
In 2003 the number of sessile oak trees was less with 67% in 
the stand as compared the number before the forest decline. 
There were only 21% decrease in the number of Austrian oak 
trees. The vertical projection of the tree canopy was used for 
evaluating the change in the canopy size and responses of 
individual trees to the structural loosening of the stand. This 
parameter of the remained sessile oak trees increased with 
14%. The canopy size of the Austrian oak increased more 
significantly (34%). 
In spring the increase of leaf area (Lm)  was more intense 
in the shade layer of the canopy in both species than in the 
sun layer. This resulted in a transitional large reduction of 
SLM in the shade leaves from the the starting high values 
measured after bud break. In case of sun leaves the starting 
phase of development of La and Lm was more balanced 
than in shade leaves. However shade leaves reaches the full 
area development earlier than sun leaves. In the lower layer 
of trees leaves can avoid the later shading influences of the 
upper canopy  with this strategy.   
In case of sessile oak the full leaf size was achieved within 
the same period in 2003 and 2004 but the area of mature 
leaves were larger in both canopy layers in 2004 than in 
2003. This is due to the differences in the rainfall conditions 
in the period of the logaritmic phase of the leaf development 
in the two growing seasons. This suggests that springtime 
drought primarily influence the potential size of assimilating 
leaf area of sessile oak. The increase of leaf mass was very 
similar in the sun and shade layers of sessile in spring. The 
mass of shade leaves reached the maximum than tha of sun 
leaves. In 2004 the mass of fully developed sun leaves was 
significantly larger than in 2003. This is due to the compensa-
tion in leaf mass as a consequence of phytophagous damages. 
The loss of leaf area int he upper canopy layer was 16%. In 
case of sessile oak the springtime increase of leaf mass was 
very similar in the sun and shade layers. Shade leaves finishes 
the development of leaf mass earlier and exhibit significantly 
smaller leaf mass than sun leaves. 
In sessile oak the area of mature leaves in growing seasons 
of 2003 and 2004 increased significantly as compared to the 
period before the forest decline (Virágh 1985). This suggests 
that the loosening of stand structure may have large influ-
ence on the canopy size and  the development of shade and 
layers of individual trees. The horizontal increase of canopy 
resulted in deeper shade in the lower layer of  trees.  In case 
of sessile oak the leaf mass of mature sun and shade leaves 
was significantly larger in 2003 and 2004 than in the period 
before the forest decline (Virágh 1985).
In the upper canopy layer of Austrian oak the leaf area 
and leaf mass did not differ  significantly from those reported 
before the forest decline. In the lower layer of the canoy, 
however, the increase of leaf area was observed but the leaf 
mass exhibited similar values.
The SLM of mature leaves was larger in the sun layer 
than in the shade layer. The maximum values of RLmGR 
was observed in spring and did differ significantly from those 
reported for the period before the forest decline.  The maxi-
mum value of RLmGR appeared 45-50 days later in case of 
the thermophyllous Austrian oak than in case of sessile oak. 
However the logaritmic phase of leaf development of Austran 
oak is shorter than in sessile oak. In 2004 there was a 17% 
loss of leaf  area in the sun layer and 6% loss of leaf area in 
the shade layer as a consequnce of photophagous damages. 
In case of Austrian oak the loss of leaf  area was smaller and 
amounted only to 1-5%.
Acknowledgements
This work was supported by the Hungarian Scientific Fund 
(Project No T037961) and National Research and Develop-
ment Proejct of Ministry of Education, Hungary (Forest and 
Climate Project No. 0196).
References
Jakucs P (1985) Ecology of an oak forest in Hungary. Acad Press, Buda-
pest.
Jakucs P, Mészáros I, Papp BL, Tóth JA (1986) Acidification of soil and 
decay of sessile in the “Sikfökut Project” area (N-Hungary). Acta Bot 
Hung 32:303-322.
Kozlowski T (1971) Growth and development of trees. Acad Press, New 
York London pp. 296-309. 
Mészáros I, Módy I, Marschall M (1993) Effect of air pollution on the condi-
tion of sessile oak forests in Hungary. In: Vernet, JP ed., Environmental 
Contamination Elsevier Sci. Publ., Amsterdam, London, New York, 
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Roderick H (1982) Plant Growth Curves. Edward Arnold Public, London. 
pp. 16-29.
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Acad Press 229-259.


Variability of leaf growth characteristics in the canopy of sessile oak and Austrian oak

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Variability of leaf growth characteristics in the canopy of sessile oak and Austrian oak

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