Volume 17(3), 17- 26, 2013 JOURNAL of Horticulture, Forestry and Biotechnology

www.journal-hfb.usab-tm.ro

17

The influence of site characteristics on beech growth in northeastern Romania Lupescu M.1*, Curca M.1

1University “Ștefan cel Mare”, Faculty of Forestry, Suceava, 13 Universității Street, 720229, Suceava,

Romania *Corresponding author. Email: lupescu.mihai@gmail.com

Abstract The influence of orographic factors on beech growth (Fagus sylvatica L.) was studied in stands located in north - eastern Romania. 52 stands were analyzed. The studied stands range from 45 degrees northern latitude to 48 degrees northern latitude and 25 degrees eastern longitude to 28 degrees eastern longitude. Statistical parameters of growth series such as the correlation between trees in a stand, the average size of annual tree ring, standard deviation and altitude, slope exposure and latitude influence on beech growth were analyzed for the period 1959-2008. Correlation study showed that this is quite low on large surfaces of the study area. The highest values are found in the eastern half of Suceava county. The highest values of radial growth are achieved in areas with average altitude that provide a favorable rainfall treatment, but there are also exceptions such as areas with low altitude from Botosani county where beech found optimal conditions for growth. Standard deviation correlated with altitude. The natural tendency is to achieve smaller variations in annual tree ring size at low altitudes, higher variations in annual tree ring size at average altitudes and lower variations of the annual tree ring size at high altitudes. The analysis of the spatial variation of the analyzed series according to altitude led to the formation of three groups. The first group consists of growth series from high altitudes - 900 m, 1000 m, 1100 m and 1200 m The second group consists of series from middle altitudes that range from 500 m to 800 m. The third group consists of growth series achieved at low altitudes - 200 m, 300 m and 400 m The explanation for series spacing is related to the environmental conditions in which these series were formed. At low and high altitudes, slope exposition has a stronger influence, leading to environmental factors changes with a larger impact on growth. The slope exposition at medium altitudes has a lower influence on growth. Hierarchical analysis (cluster) of the series led to grouping according latitude.

Key words spruce, variability, radial growth, altitudinal gradient

The annual tree ring width varies from year to

year due to the environmental factors influence. Their

variation can be annual or periodical and their

influence may reflect on the growth achieved in one or

several years. The correlation between the annual tree

ring size and environmental factors is influenced by the

species ecological requirements or by factors from the

extreme years 16

.

Climate and the orographic characteristics of

sites are the most important factors of tree growth in

any environments where the forest exist. In the

mountainous areas temperature and precipitation vary

along with altitudinal gradients, so does forest

vegetation. Annual growth rings of trees provide the

information about the response of forests to a variety of

environmental perturbations. Tree ring series contain a

series of signals that represent the sum of the

environmental influences on a tree growth 2. Climate

signal is considered as one of the main controlling

factors for the tree growth. The annual tree ring size is

achieved under the cumulative influence of all factors

that influence growth. In its analysis, all the influences

that appear during the growth and evolution of forestry

vegetation must be considered. The tree ring formation

depends on species and on the place where it grows

and expands.

In this study there were taken into account

environmental factors as altitude, exposition and

latitude in order to underline their influence over

growth on beech (Fagus sylvatica L.)

The objective of this study was to analyze

environmental factors as altitude, exposition and

latitude with the aim to demonstrate their influence

over beech growth.

18

Material and Methods

Beech has an extended growth area. A number

of 52 stands were chosen for study. The studied stands

range from 45 degrees northern latitude to 48 degrees

northern latitude and 25 degrees eastern longitude to 28

degrees eastern longitude. In Figure 1 the distribution

of beech stands is presented.

Fig.. 1. The distribution of beech stands

The stands where beech is the predominant

species are as well arranged on two groups: one is

found in Suceava county and Botosani county and the other is found in Neamt county and Bacau county. The stands are part of the National Forestry Inventory with the distance between points being 4 km. The layout of stands in which the beech is predominant species made possible a separation by longitude of two groups. In each stand was registered the geographical coordinates, altitude, exposition, average slope, flank position, production class, station type, class and type

of soil. Stands altitude for beech varies between 233 m

in the stand F112 and 1151 m in the stand F106. The

altitude classes poorly represented are class 200 m and

1200 m class with one stand each. The most frequent

altitude class found is 500 m with ten stands included.

The southern exposition was determined in 24 stands,

while the northern exposition proved to be

predominant with a number of 28 stands.

From the 52 stands with beech have been

processed a total of 580 growth samples.

The growth samples were taken with the

Pressler increment borer and transported in special

plastic supports. The growth samples were fixed on

wooden plates with adhesive and after its drying, the

samples were ground, in different stages with abrasive

tapes of different granulation, starting from those rough

to the fine ones.

The width measurement of the annual tree ring

was done with the help of the programme Coorecorder.

The precision offered by the programme is of 0,01mm.

The data obtained from the measurements were stored

in the form of electronic files for each growth sample.

In the first stage, the measurements were introduced in

the C – dendro programme where the sampling year

was given. The next stage was the cross dating process

for attributing each ring to its formation date. The cross

dating process was accomplished in two steps. In the

step stage a primary cross dating was done with the

help of the Coorecorder programme by comparing each

growth curve with a growth reference curve calculated

from the total of growth curves, for each species

separately. The analysis was done on segments, both

visually as well as with the help of automatically

calculated correlation coefficients. It was specially

insisted on the period proposed for study (2008 –

1959). The second cross dating step was done with the

help of the Cofecha programme. On the base of the

hints offered by the programme, checkouts were done

over the measurements and corrections were made in

19

the case when these proved to be real. The growth

samples which meaurements didn’t reasonably

correlate with the stand (correlation coefficient <0,2),

were excluded from the study.

The processing of growth series was done with

the help of Arstan programme. Through statistical

processing with Arstan3 programme the statistical

characteristics of each stand were obtained. The main

statistical parameters calculated were: the length of the

dendrochronological series, the minimal year of the

dendrochronological series, the minimal width value

of the measured annual tree ring from the

dendrochronological series, the maximum width value

of the measured annual tree ring from the

dendrochronological series, the maximum year from

the dendrochronological series, the average value of

annual tree rings width, variance, the standard

deviation, average sensitivity, first degree

autocorrelation, correlation.

The parameters of the growth series were

calculated with the programme Arstan6. The

standardization of growth series was done with Arstan.

The growth series standardization implies the

procedure of transforming the chronological series,

representing the size of the annual ring, in a series of

data by extracting a certain signal through the method

of relating the size of the annual tree ring to a value

obtained through a function. For standardizing the

growth series it was used the Arstan programme. The

first standardization was applied in order to exclude the

age influence with an exponential function and then a

second standardization was applied through a cubic

spline function with a length of 20 years for excluding

disturbing endogenous and exogenetic factors.

Results and Discussions

The longest series is analyzed between 1672

and 2010, found the stand F151. The average

calculated age for a stand is the highest in F123 with an

average age of 203 years and the stand with the lowest

average age is calculated in F103 with an average age

of 32 years. Beech proved to be the species with the

highest average age of the species analyzed.

The minimum number of growth samples

processed in stands was 10 samples, and the maximum

number of growth samples processed in stands was 16.

The correlation coefficients in the stand ranged

from 0,299 in stand F125 to 0,684 in stand F146.

Average correlation of all stands has a value around

0,451. This value is smaller that of the fir, but higher

that of spruce.

Radial growth accomplish by the beech ranges

from minimum values of 1,356 mm in stand F106 to

maximum values of 3,316 mm in F129 stand. The

standard deviation of the average actual growth is

between the values of 0,293 in F113 stand and 0,933 in

F124 stand.

Autocorrelation varies between 0.478 in F117

stand and 0.834 in F133 stand.

The standardized indices have an averaged

value that is close to the value 1, with standard

deviations of minimum 0,002 in F145 stand and

maximum of 0,142 in F133 stand.

Sensitivity ranges from minimum values of

0,213 in F129 stand to maximum values of 0,422 in

stand F112.

Autocorrelation for standardized values ranges

from a minimum value of 0,032 in stand F138 and

maximum values of 0.327 in F122 stand.

Correlation between trees in a beech stand was

calculated and plotted in the form of thematic map with

contour lines and a color scheme. Map is shown in

Figure 2.

20

Fig. 2. The correlation study depending on geographic position

Correlation study showed that it is quite low in

large areas of the study area. The highest values are

found in the eastern half of the Suceava county and

punctually in Bacau county. The lowest values of

correlation are found in northwestern Neamt county.

The distribution of the correlation values is also

punctual correlation with altitude is low. Correlation

values are given specific characteristics of the local

climate.

The average annual radial growth accomplish

by beech in the period 1959-2008 in the study area was

used to achieve a thematic maps. Map made is shown

in figure 3.

Fig. 3. The radial growth study depending on geographic position

21

Average size of annual ring made by beech in

the last 50 years varies greatly across the study area.

The highest values are found in Suceava county and

Botosani county (south-west part). The higher average

growth are also met punctual in Neamt county and

Bacau county. The highest values are found in areas

with medium altitude that provides a favorable rainfall

regime, but there are exceptions such as the low

altitude stands with beech in Botosani county where he

found the optimal conditions for growth. Stands in that

beech achieved lower average radial growth are

situated either at high altitudes, such as the mountain

part of Bacau county and punctual in Neamt county

and Vaslui county due to specific local climatic

conditions

The variations of the standard deviation of the

standardized series of growth was studied by mapping

the study area with specific software. Map made is

shown in Figure 4, it is shown the variation in the

standard deviation for the standardized series.

Fig. 4.. The standard deviation study depending on geographic position

For standard deviation, correlation with altitude

is reflected by the fact that high standard deviation

stands are located at high altitudes, 900 - 1000 m and at

low altitudes, 200 m, but this is not the uniform in the

study area. Distribution of standard deviation values is

punctual, with areas of minimum and areas of

maximum due to specific local conditions.

Principal component analysis is a statistical

method for determining the spatial variability,

information that is stored in the annual ring. For

principal component analysis were used standardized

series calculated with Arstran program. Analysis of

altitude influence on growth was analyzed for ten

classes of altitude. For each class of altitude was

calculated the average growth indices of all samples

taken at that altitude. The data was entered into

Microsoft Excel and principal component analysis was

performed. The graphical representation is shown in

figure 5.

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200 m

300 m

400 m

500 m600 m

700 m

800 m

900 m

1000 m1100 m

1200 m

-3

-2

-1

0

1

2

3

-5 0 5

PC

2 (

10.4

%)

PC 1 (66.7%)

Fig. 5. Principal component analysis depending on altitude

Series analyzed were named according to

altitude class they belong. The first two principal

components analysis expressed 77.1 % of the

variability of the growth samples and the first

component explains 66.7% of the variability of the

growth samples. Analysis of the spatial variation of the

series according to altitude determined the formation of

three groups. The first group consists of series growing

at high altitudes - 900 m, 1000 m, 1100 m and 1200 m

The second group consists of middle altitude that

ranges from 500 m to 800 m. Third group consists of

series of growth achieved at low altitudes - 200 m, 300

m and 400 m. The spacing of the series is related to

environmental conditions in which they formed. Each

group of altitude expresses unique environmental

conditions in which the trees that make up the series

grew. At high altitudes, marginal habitat, beech

undergoing limiting environmental factors, mainly

temperature. Series of growth achieved at intermediate

altitudes receive normal to optimal conditions of

growth. Low altitudes, marginal habitat, beech

undergoing limiting environmental factors, mainly

rainfall. The three groups can be subdivided into

smaller groups. The group at high altitudes group the

altitude of 900 m, 1000 m and 1200 m series and 1100

m altitude series distance from the others with specific

growths probably due to specific conditions from local

factors. In the middle altitude group the series formed

at altitudes between 500 m and 600 m are closer due to

similar environmental conditions for growth. Also,

there is an approach between the series of altitude of

700 m and 800 m, still due to similar environmental

conditions of growth. In the low altitude group appears

closer ties between series at altitudes of 300 m and 400

m due to similar environmental conditions for growth

and the series at altitudes of 200 m distances

themselves due the increases of limiting local factors.

Principal component analysis is a statistical

method for determining the spatial variability,

information that is stored in the annual ring. For

principal component analysis were used standardized

index series calculated Arstran program. The influence

of altitude on growth was analyzed at Spruce ten

classes of altitude made for exhibitions and exhibitions

sunny shade.

Study of the exposition influence on the growth

of the beech was conducted for the three groups of

altitudes resulted from principal component analysis

for altitude. Within each altitude group, there were

analyzed series of standardized indices. Notation was

made with numbers and letters, numbers representing

altitude class and letters representing type of exposition

(I - southern, U - northern). The results are the figures

6, 7 and 8.

23

200 m U

300 m I

300 m U

400 m I

400 m U

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

-10 -5 0 5

CP

2 (

13,8

%)

CP 1 (72,7%)

Fi

g. 6. Principal component analysis depending on exposition for lower altitudes

In the first group of altitude, which contains low

altitudes between 200 m and 400 m, the series analysis

were grouped according to the type of exposition. The

series with northern exposition have negative values on

the second axis, the axis of the second main

component. Stands situated on the southern exposition

have positive values and negative values very close to

the value 0 on the second axis. In this case, the first

component expressed 72.7% of the variability in series,

and the second main component expressed 13.8% of

the variability in the series.

500 m I

500 m U

600 m U

700 m I

700 m U

800 m I

800 m U

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

-5 0 5

CP

2 (

6,2

%)

CP 1 (80,8%)

Fig. 7. Principal component analysis depending on exposition for middle altitudes

In the second group of altitude, which contains

classes of altitude between 500 m and 800 m, the

layout of the series does not shows the exposition

being a factor that is determining the variability.

Spatial arrangement of the series is mainly carried out

according to altitude, low altitude classes have lower

values and higher elevation classes have higher values

on the second axis.

24

900 m I

900 m U

1000 m I

1000 m U

1100 m I

1200 m U

-2.0

-1.5

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

-5 0 5

CP

2 (

10

,8%

)

CP 1 (65,6%)

Fig. 8. Principal component analysis depending on exposition for higher altitudes

In the case of the third group of altitude, the

analysis determined the clearest layout of the

standardized series according to the type of exposition.

The series with northern exposition have negative

values on the second axle and the ones with southern

exposition have positive values on the second axis.

Grouping was done after the second main component

explaining 10.8% of the spatial variability.

The analyzes performed have shown that the

influence of slope exposition is strongest in the class of

altitude marginal to distribution of beech, the influence

is most of temperature and moisture regime. In the

middle altitude classes, exposition influence on beech

growth is much reduced.

Spatial variability analysis was performed for

the studied stands depending on latitude. In the first

group are found seven stands: F102, F103, F104, F105,

F107, F108 and F109 which are located in the southern

study area. Northern group comprises six stands: F140,

F141, F144, F145, F146 and F147. Analysis of spatial

variability for latitude was done through hierarchical

analysis (Cluster) with Microsoft Excel in witch were

introduced standardized series obtained with Arstan

program for each stand. Graphical representation

obtained is shown in Figure 9.

F147

F141

F109

F105

F108

F104

F102

F144

F145

F107

F140

F146

F103

0.20

Fig. 9. Cluster analyses depending on latitude

25

It was achieved a grouping of the series from

different stands. The first group contained two stands

that share group latitude, the two stands are part of the

southern latitude, although they are located at different

altitudes. The second group includes two stands: F109

and F105. They are part of the southern latitude located

at different altitudes. The third group consists of series

of three stands: F147, F141 and F144. They are part of

the northern latitude located at different altitudes. In

this group is the strongest link between the series of

two stands: stand growing series F147 and stand

growing series F141. We can observe also two larger

groups: a southern group and the northern group. The

first large group is the southern group. It consists of

series from stands F108, F104, F102, F145, F109 and

F105. Of these, only F145 is located in the northern

area, but this analyzed series is formed at a low

altitude: 400 m. Occurs a compensation of

environmental factors resulting in similar increases,

which leads to the introduction of this stand southern

group. The second large group consists of stands F147,

F141, F144, F107, F140 and F146. This is the northern

group, with one exception: the stand F107, located in

the southern study area, at an altitude of 700 m on

southern exhibition. It is possible that this series is

formed in specific local site conditions, which could

express inclusion in this group.

Conclusions

Correlation study showed that, at the extremes

of studied altitude, approximately equal to the limits of

the natural area of distribution, the correlation between

the growth of trees is higher. The average radial growth

for all stands with beech is 2.08 mm. The natural

tendency is to have smaller growth values at lower

altitudes, higher values of the radial growth at middle

altitude and lower growth values at high altitudes.

The standard deviation is related to the size of

the annual ring. The natural tendency is to have smaller

variations of the growth series at lower altitudes,

higher variation at middle altitude and lower growth

variation at high altitudes.

Analysis of the spatial variation of the series

analyzed according to altitude caused the formation of

three groups. The first group consists of series growing

at high altitudes: 900 m, 1000 m, 1100 m and 1200 m

The second group consists of middle altitude classes

that ranges from 500 m and finishing with 800 m. The

third group consists of growth series achieved at low

altitudes: 200 m, 300 m and 400 m. The spacing series

explanation is related to environmental conditions in

which they formed this series. Each group of altitude

expresses unique environmental conditions in which

the trees grew. At high altitudes, marginal habitat,

beech is undergoing limiting environmental factors,

mainly temperature. Series of growth achieved at

middle altitudes receive normal to optimal temperature

and water quantities. Low altitudes, marginal habitat,

beech is undergoing limiting environmental factors,

mainly rainfall. In the case of exposition, the resulting

conclusion is that at low and high altitude exposition

has a strong influence, leading to changes in

environmental factors with larger impact on growth.

Exposition at middle altitude has an lower influence.

Latitude affects beech growth both through

annual climatic variations, which determines stronger

changes in the growth, and by changing temperature

and precipitation regime by moving in the temperate

latitude. A lower quantity of precipitation determines

the development of lower growth, even if the

temperature regime is more favorable to growth.

Acknowledgment

This paper was supported by the project

"Improvement of the doctoral studies quality in

engineering science for development of the knowledge

based society-QDOC” contract no.

POSDRU/107/1.5/S/78534, project co-funded by the

European Social Fund through the Sectorial

Operational Program Human Resources 2007-2013.

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