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COMPARATIVE ANALYSIS OF SOME BIOECOLOGICAL CHARACTERISTICS OF HUNGARIAN OAK AND TURKEY OAK
MARINA VUKIN1 and LJ. RAKONJAC2
1 Faculty of Forestry, University of Belgrade, 11030 Belgrade, Serbia 2 Institute of Forestry, 11030 Belgrade, Serbia
Abstract – his paper gives an in-depth study of some bioecological characteristics of the Hungarian and Turkey oak, autochthonous oak species and ediicators of climatogenic communities of central Serbia. Today, these forest complexes are mostly of coppice origin and as such, they require implementation of reclamation operations. In order to determine biological dominance, select the optimal reclamation operations and inally improve the state of these forests, we studied the environmental conditions, stand state, development and position of individual trees in a mixed coppice stand of Hun-garian and Turkey oak in a suburban zone of the city of Belgrade.
Key words: Hungarian oak, Turkey oak, stand state, tree development, bioecological characteristics
INTRODUCTION
A large part of urban areas in the central part of our country, at altitudes between 300 and 700 m. a.s.l., is surrounded by a widespread Hungarian oak and Turkey oak forest (Quercetum frainetto-cerris Rud. 49 s. l.), which is a climatogenic forest typical of Serbia and as such it is considered to be its ‘coeno-ecological synonym’ (Jovanović, 1986). his community occurs on placoric terrains, i.e. on sites where there is just enough water in the soil for that type of climate. It is inluenced by a combination of central European, continental-steppe and submediterranean climate and vegetation. In the lower part of their altitudinal range, in the vicinity of human settlements, espe-cially in Šumadija, the forests of Hungarian oak and Turkey oak have been greatly deforested, so that to-day they make complexes of diferent size and private forest preserves. here are larger complexes of these forests in the foothills of mountains, but they are, for the most part degraded, while better-preserved
stands can be found only in monastery preserves and in special-purpose forests (Stajić, 2007). Due to frequent and extensive felling operations and other adverse efects, these are mainly even-aged coppice stands. As a species of great coppice vigor, the Hun-garian oak is more threatened by felling because it yields better quality wood. herefore, Hungarian oak trees of generative origin are rarely found (Jovanović, 2007). For all these reasons, there is a prevailing opinion that Turkey oak trees outnumber Hungarian oaks on the large areas of this community.
so far because most of these forests are in private ownership. However, in recent years, detailed inves-tigations of coppice stands of Hungarian oak and Turkey oak have been conducted with the aim of se-lecting the most efective reclamation operations in the central zone of these forests (Isajev et al., 2006; Stajić and Rakonjac, 2006; Stajić, 2007; Stajić et al., 2008; Stojanović et al., 2006a, 2006b, 2007; Vukin and Bjelanović, 2006, 2010; Vukin and Stavretović, 2007; Krstić et al., 2010). Since the center of its range of distribution is in Serbia, the community of Hungarian oak and Turkey oak and the bioecologi-cal characteristics of these species have not been studied by foreign authors.
In order to adopt efective reclamation measures in mixed forests, it is very important to be familiar with the bioecological characteristics of tree species. Considering all the above presented facts, the follow-ing primary tasks of this research study were estab-lished: (i) to make a comparative analysis of the most important bioecological characteristics of Hungar-ian oak and Turkey oak; (ii) to determine which spe-cies is ‘biologically stronger’ in the investigated stand and to deine further guidelines for making a suitable and desirable mixture of species in future reclama-tion operareclama-tions.
MATERIALS AND METHODS
he ield data were collected in a mixed coppice for-est of Hungarian oak and Turkey oak in the territory of Lipovica, which is in the suburban zone of the city of Belgrade. In the selected stand, the percentage of Hungarian oak and Turkey oak is approximately the same. Four sample plots were singled out and the data were collected by applying the permanent sample plot working principle. Average values for all four sample plots were used in calculations. All ield investigations were carried out from 2006 to 2009, during the vegetation period. he criteria for the se-lection of stands were afected by the uniformity of site and stand conditions within the selected sample plots. he investigations included the study of eco-logical conditions, stand state, development and bio-logical status of trees.
Height curves and diameter increment lines were analytically itted. Biological position of the trees was determined by using the methodology of the Faculty of Forestry in Belgrade. Sample trees provided aver-age data for the study stand, which were then statisti-cally processed at the stand level. Computer sotware Statgraph and Statistica 6 were used for the statistical data processing. he data are presented both in dia-grams and charts.
RESULTS AND DISCUSSION
Basic ecological conditions
Due to the format limit of this paper, we can present only the inal results of studying the ecological condi-tions. he selected stand is located within compart-ment 42 of the FMU Lipovica, at an altitude of 175-185 m, slope of approximately 12° and southwestern exposure. his is a coppice stand of Hungarian oak and Turkey oak, 65 to 70 years old. Within the study of climatic factors, the following values of the hy-dric balance elements were obtained: aridity index (Ia) 19.54; humidity index (Ih), 13.37 and climate
index (Ik) 2.64. hese values indicate that the study
area has a subhumid moist climate of C2 type. here
were certain variations in the type of climate in the study period, from arid type E (in 2000) to humid temperate type B2 (in 1999). he soil is classiied as
lessive brown and phytocoenologically it is a typical forest of Hungarian oak and Turkey oak (Quercetum frainetto-cerris aculeatetosum). he standis typologi-cally classiied as a Typical forest of Hungarian oak and Turkey oak (Quercetum frainetto-cerris aculea-tetosum) on lessive brown soil.
Stand state
he basic data on the investigated stand are pre-sented in Table 1. he average total number of trees is 520 trees per ha, ranging from 420 to 580 trees per ha. he average total number of Turkey oaktrees is 210 trees per ha or 40.4%,ranging from 120 to 260 trees per ha. he average total number of Hungarian oaktrees is 270 trees per ha or 51.9%, ranging from160 to 320 trees per ha. Other species
participate with 40 trees per ha or 7.7%. Taking into account the average data for all four sample plots, we can conclude that the trees are distributed in di-ameter degrees of 5 to 35 cm, with the maximum abundance of 33.7% in 20 cm diameter degree (Ta-ble 2). he distribution of trees indicates a binomial structure characteristic for even-aged stands. he mean stand diameter is 23.8 cm, or 28.2 cm for Tur-key oak and 21.5 cm for Hungarian oak. he mean stand height is 23.4 m, or 26.6 m for Turkey oak and 22.3 m for Hungarian oak. he attained diam-eters and heights clearly show that Turkey oak is the dominant species in this stand. he total wood vol-ume amounts to 262.9 m3/ha, 152.0 m3/ha or 57.8%
of which isTurkey oakwood volume, and 110.1 m3/
ha or 41.8% Hungarian oak. Other species account for 0.9 m3/ha or 0.4 % of the total wood volume. he
basic statistical data are presented in Table 3. he analysis of variance shows that the deviation of the number of trees and volume both on the overall lev-el and individually for Hungarian oak and for Tur-key oak is statistically random. Similar results were obtained in the statistical analyses of the stand state in the forests of Hungarian oak and Turkey oak by Cojoaca (2010) and Cojoaca et al. (2011).
Growth of individual trees of Hungarian oak and Turkey oak
he study of trees, i.e. their diameters and heights, is one of the most accurate means of determining cer-tain bioecological characteristics of tree species.
For the purposes of dendrometric analysis of Hungarian oak and Turkey oak trees, three trees of both species were singled out from the 20% of the strongest trees in the study stand. his paper stud-ies only the average values of diameter and height growth as well as current diameter and height incre-ment, comparatively for both species. he compara-tive analysis of the average values of diameter devel-opment and current diameter increment of Hungar-ian oak and Turkey oak is given in Graph 1.
Based on the obtained results, it can be concluded that both species reach the irst culmination of their diameter increment at the same time, at the age of 10, which is followed by a decline up to the age of 20, when the value of increment starts to increase again.
he second culmination starts between ages 25 and 35, and it continues up to the age of 40 in Turkey oak. he attained values of current diameter increment of Hungarian oak and Turkey oak are almost identical at the irst peak time, with a slightly stronger incre-ment of Turkey oak. However, as early as the second culmination, which starts at the age of 20, Turkey oak suddenly stands out by attaining higher values of current diameter increment, by 2 mm or by 30-40%. By analyzing diameter development of Turkey oak in comparison to Hungarian oak, it can be con-cluded that Turkey oak starts to stand out around the age of 30. Until the end of the analyzed period (65 years), the values of Turkey oak diameter con-tinue to increase in comparison to Hungarian oak. Comparative analysis clearly indicates that in these stands, Turkey oak, at the same age and in the same ecological conditions, ater the age of 25 attains fast-er growth and largfast-er diametfast-ers, which makes it the dominant species in the given mixture. Comparative analysis of the average values of height development and current height increment of Hungarian oak and Turkey oak is presented in Graph 2.
Graph 1. Average values of diameter development and current diameter increment of Hungarian oak and Turkey oak.
he line of Hungarian oak and Turkey oak de-velopment shows that both species reach their irst culmination of current height increment around the age of 15, ive years later than the culmination of the current diameter increment. his is common for artiicially established stands and, to some ex-tent, for coppice forests. Current height increment experiences a decline until the age of 25, and then it increases again, reaching a second culmination be-tween the age of 30 and 40, which is again ive years later than the culmination of the current diameter increment.
Turkey oak attains higher values of current height increment than Hungarian oak from the be-ginning of its development, and as early as the irst culmination this value is higher by 0.1 m or 20%. he values of the second culmination of Turkey oak current height increment are higher by about 0.2 m or 40%. It is interesting that ater the age of 40, the current height increment in Turkey oak becomes equal to the increment of Hungarian oak and this tendency is maintained until the end of the analyzed period (65 years). he line of height development shows that at the age of 10 Turkey oak is already superior in comparison to Hungarian oak and from the age of 20, or 35, it constantly maintains higher height values (from 2.0 to 3.0 m). All these facts in-dicate that Turkey oak, when compared to Hungar-ian oak, reaches larger dimensions both in diameter and in height, which makes it the dominant and biologically stronger species in the studied mixture. his distinctive bioecological characteristic is a de-ciding factor in the selection of suitable silvicultural and reclamation operations. he above statement changes the current views expressed in the exist-ing textbook literature (Stojanović and Krstić 2000, 2006; Jovanović 2007; and other authors) in which Turkey oak is considered to be biologically weaker than Hungarian oak due to its susceptibility to frost cracks and snow breaks. he lower percentage of Hungarian oak in the given mixture is attributed to the negative efects of the anthropogenic factor since the wood of Hungarian oak has a better utility value.
Bioecological characteristics of Hungarian oak and Turkey oak
With regard to the ecological conditions, both species have similar bioecological characteristics because they oten occur in mixed communities. However, there are certain diferences. Regarding light, both species are true heliophytes. Regarding resistance to low temperatures, Turkey oak is more vulnerable and prone to frost cracks and snow breaks because it keeps its leaves deep into the winter. Regarding soil, Turkey oak is well adapted to soil of low acid-ity, while Hungarian oak prefers serpentinite and grows only on acid soils. here are numerous other bioecological characteristics that are similar in these two species, but Hungarian oak yields better qual-ity technical wood which is used for the production of technical timber. However, the research carried out in this study shows that Turkey oak, in compari-son to Hungarian oak, attains higher values of cur-rent diameter and height increment, which indicates that, at the same age, it has larger dimensions, and this fact makes it the biologically stronger species in the mixture. Since in regenerated stands of Hungar-ian oak and Turkey oak, HungarHungar-ian oak has slower growth from the early age and this unfavorable po-sition makes its growth even slower, the percentage of Turkey oak is signiicantly greater in majority of these forest communities.
CONCLUSION
MARIN
A VUKIN
E
T AL.
SAMPLE PLOT Turkey
oak
Hungarian oak
Turkey oak
Hungarian oak
N V N V N V N V
po ha % m3/ha % per ha % m3/ha % per
ha % m3/ha %
po
ha %
m3/
ha %
1 29.0 21.2 26.8 22.2 580 100 322.9 100 260 44.8 198.2 61.4 320 55.2 124.7 38.6 - - -
-2 31.9 22.3 27.5 22.6 540 100 276.8 100 120 22.2 111.6 40.3 380 70.4 163.5 59.1 40 7.4 1.7 0.6
3 27.1 20.9 26.1 22.0 540 100 244.4 100 240 46.2 160.5 66.1 220 42.3 83.0 34.1 60 11.5 0.9 0.6
4 27.1 20.9 26.1 22.0 420 100 207.5 100 220 52.4 137.9 66.5 160 38.1 68.6 33.1 40 1.0 0.9 0.4
average values
C
O
MP
AR
A
TIVE AN
AL
Y
SIS O
F SO
ME B
IO
EC
O
LO
GI
CAL CH
AR
A
CTERIS
TI
CS O
F HUN
GARI
AN O
AK AND TURKE
Y O
AK altitude: 175-185 m compartment 42 exposure: SW
TYPOLOGICAL CLASSIFICATION: Typical forest of Hungarian oak and Turkey oak (Quercetum farnetto-cerris aculeatetosum) on lessive brown soil
diameter degree (cm)
total Turkey oak Hungarian oak lowering ash + cherry + w. service tree + horn-beam + elm
N V N V N V N V
per ha % m3/ha % per ha % m3/ha % per ha % m3/ha % per ha % m3/ha %
5 25 4.8 0.29 0.1 25 62.5 0.29 31.5
10 20 3.9 0.85 0.3 5 2.4 0.22 0.1 15 37.5 0.63 68.5
15 35 6.7 6.51 2.5 0 0.0 0.00 0.0 35 13.0 6.51 5.9
20 175 33.7 59.89 28.8 35 16.7 11.76 7.7 140 51.8 48.13 43.8
25 140 26.9 77.86 29.6 60 28.6 34.24 22.5 80 29.6 43.62 39.7
30 70 14.4 62.06 23.6 60 28.6 50.35 33.1 15 5.6 7.81 10.6
35 50 9.6 55.49 21.1 50 23.8 55.49 36.5
40
Σ 520 100 262.9 100 210 100 152.06 100 270 100 109.96 100 40 100 0.92 100
dg = 23.8 cm dg = 28.2 cm dg = 21.5 cm dg = 7.3 cm
hg = 23.4 m hg = 26.6 m hg = 22.3 m hg = 7.8 m
Iv = m3/ha Iv = m3/ha Iv = m3/ha Iv = m3/ha
piv = % piv = % piv = % piv = %
stand age: 65-70 years
percentage of Turkey oak in the mixture
percentage of Hungarian oak in the
mixture percentage of other species in the mixture
per N = 40.4% per N = 51.9% per N = 7.7%
per G = 57.2% per G = 42.0% per G = 0.5%
per V = 57.8% per V = 41.8% per V = 0.4%
mean height is smaller by 4.3 m. (iii) he total wood volume amounts to 262.9 m3/ha. Hungarian oak
participates with 110.0 m3/ha or 41.8%; Turkey oak
with 152.1 m3/ha or 57.8% and other tree species
with 0.9 m3/ha or 0.4%. (iv) In the category of tree
biological position I, Turkey oak trees participate with 83% and Hungarian oak with 37% trees. he percentage of Turkey oak trees in the category of biological position III is 2% and Hungarian oak 5%. All these data indicate that both species are extreme heliophytes but the slow growth of Hungarian oak brings it into a codominant position and suppressed part of the stand. (v) he irst culmination of current diameter increment starts at the age of 10 in both species, the second between the age of 25 and 35. At the time of the second culmination, Turkey oak attains 30 to 40% higher values of current diameter increment than Hungarian oak. (vi) he irst culmi-nation of current height increment occurs around the age of 15 in both species, the second between the age of 30 and 40. From the very beginning of height increment development, Turkey oak attains 20-40% higher values, which makes it dominant in the stand. Our investigations into the development
of individual trees in mixed coppice stands of Hun-garian oak and Turkey oak leads us to conclude that in the given mixture Turkey oak is the biologically stronger species in comparison to Hungarian oak. his fact must be taken into account when selecting and adapting suitable reclamation operations.
REFERENCES
Banković, S., Medarević, M., Pantić, D., and N. Petrović (2009). Тhe National Forest Inventory of the Republic of Serbia.
Ministry of Agriculture, Forestry and Water Management of the Republic of Serbia – Forest Directorate, Belgrade.
Cojoaca, F. D. (2010). Researches on the structure, the growth and the production of Turkey oak and Hungarian oak stands in Oltenia Plain – PhD hesis, University Transyl-vania of Brasov
Cojoaca, F. D., Netoiu, C., and I. Bercea (2011). Mathematical models to the structure of Turkey oak and Hungarian oak stands in Oltenia plain. Annals of the Univeristy of Craiova.
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Isajev, V., Vukin, M., and V. Ivetić (2006). Unošenje drugih vrsta drveća u hrastove šume sa posebnom namenom u Srbiji.
Šumarstvo br. 3. Beograd. str. 29-47.
Table 3. Statistical indicators of diameter and volume structure
Element Total Turkish Oak Hungarian Oak Other Species
N V N V N V N V
Count 4 4 4 4 4 4 4 4
Average 520,0 262,94 210,0 152,06 270,0 109,96 40,0 0,925
Standard deviation 69,982 49,2149 62,1825 36,6863 98,6577 42,9002 32,6599 0,71514
Coef. of variation (%) 13,35 18,9 29,6 24,1 98,6 42,9 32,6 0,71
Minimum 420,0 207,5 120,0 111,6 160,0 68,6 0 0
Maximum 580,0 322,9 260,0 198,2 380,0 163,5 60,0 1,75
Range 160,0 115,4 140,0 86,6 220,0 94,9 80,0 1,75
Stnd. skewness -1,26 0,15 -1,30 0,329 0 0,458 0 -0,188
Stnd. kurtosis 1,179 -0,296 1,103 -0,058 .1,12 -0,802 0,61 0,62
Table 4. Biological position of trees in the study stand
species
position (%)
I II III
Turkey oak 83 15 2
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