Electronic Journal of Polish Agricultural Universities (EJPAU) founded by all Polish Agriculture Universities presents original papers and review articles relevant to all aspects of agricultural sciences. It is target for persons working both in science and industry,regulatory agencies or teaching in agricultural sector. Covered by IFIS Publishing (Food Science and Technology Abstracts), ELSEVIER Science - Food Science and Technology Program, CAS USA (Chemical Abstracts), CABI Publishing UK and ALPSP (Association of Learned and Professional Society Publisher - full membership). Presented in the Master List of Thomson ISI.
2004
Volume 7
Issue 2
Topic:
Forestry
ELECTRONIC
JOURNAL OF
POLISH
AGRICULTURAL
UNIVERSITIES
Wilczyński S. , Feliksik E. 2004. THE DENDROCHRONOLOGICAL MONITORING OF THE WESTERN BESKID MOUNTAINS (SOUTHERN POLAND) ON THE BASIS OF RADIAL INCREMENTS OF NORWAY SPRUCE (PICEA ABIES (L.) KARST.), EJPAU 7(2), #07.
Available Online: http://www.ejpau.media.pl/volume7/issue2/forestry/art-07.html

THE DENDROCHRONOLOGICAL MONITORING OF THE WESTERN BESKID MOUNTAINS (SOUTHERN POLAND) ON THE BASIS OF RADIAL INCREMENTS OF NORWAY SPRUCE (PICEA ABIES (L.) KARST.)

Sławomir Wilczyński, Edward Feliksik

 

ABSTRACT

A short- and long-term variation of the tree-ring size of Norway spruce trees growing in 25 stands situated at various altitudes in the Western Beskid Mountains are discussed. It was found that air temperatures of winter and early spring were the most influential factors affecting the variation of radial increments. Also the temperature and precipitation of summer had a significant effect on the tree-ring size. Trees in the altitudinal zones: 450-750  m, 800-900  m and 950-1200  m showed a different increment rhythm. The air temperatures of summer were the factors differentiating their increment reactions. Trees growing above 950  m had the greatest thermic requirements. While trees growing between 800 and 900  m were mainly under a strong influence of pluvial conditions. Probably the air pollution was a significant factor, which during 1970-1985 weakened the biological activity of trees growing above 950  m. Since the mid-1990s there was an increase of average tree-ring sizes, and also the amplitude of changes of the ring size increased. This reflected an increased susceptibility of trees to meteorological stimuli of the environment, which may be the cause of their weakening and mass dying, mainly in the altitudinal zone of 800-900  m.

Key words: Picea abies, tree-ring, dendroclimatology, monitoring, dendrochronology, Beskidy Mountains..

INTRODUCTION

The history of the metabolic reactions of trees to environmental stimuli is registered in the form of a chronological sequence of the tree-ring sizes. The analysis of annual variation of radial increments permits to identify the climatic conditions affecting the growth of trees in diameter, as well as to determine the role played by different meteorological elements in their life cycle, and thus to verify the knowledge concerning their climatic requirements [2, 21].

During this study an attempt was made to find the causes of increasing mortality of Norway spruce in the Beskid Mountains, suspecting that the increasing frequency of occurrence of anomalous weather conditions during recent years and the expected climatic changes are among them [19].

The aim of the study was to determine the effect of the air temperature and precipitation, as well as the air pollution on radial growth of Norway spruce growing at different altitudes in the Western Beskid Mountains.

MATERIAL AND METHODS

Twenty five Norway spruce stands were selected for this study in the Beskid Mały, Beskid Żywiecki and Beskid ¦l±ski Mountains (Tab. 1). The study sites represented Norway spruce populations growing at different altitudes on slopes of different exposures. In each locality 30 dominant trees without disease symptoms were chosen. From each tree a core was taken with an increment borer, 130 cm above the ground. The width of annual rings was measured on each core thus obtaining 30 chronological sequences of the tree-ring widths (dendroscales) for each site. The correctness of dating was verified with the computer program COFECHA [13].

Table 1. Description of study sites

Forest District

Forest
Division

Site code

Elevation [m] Exposure

Site
type

Soil
(WRB - 1998)

Age of trees

Węgierska
Górka

Lipowa 118

G1150

1150/S

MMCF

Haplic Podzols

110

Żabnica 35

G650

650/SW

MMBF

Dystric Cambisols

100

Żabnica 52

G600

600/SW

MMBF

Dystric Cambisols

125

Bielsko

Jaworze 154

B500

500/N

MMBF

Dystric Cambisols

110

Jaworze 184

B750

750/NW

MMBF

Haplic Podzols

100

Wielka Ł±ka 128

B1000

1000

MMCF

Haplic Podzols

100

Wisła

ZapowiedĽ 109

W600

600/SW

MMBF

Dystric Cambisols

110

Malinka 142

W950

950/SW

MMBF

Dystric Cambisols

120

Dziechcinka 22

W700

650/NW

MMCF

Haplic Podzols

130

Ujsoły

Złatna 8

U850

850/SE

MMBF

Haplic Arenosols

130

Gawłowskie 100

U700

700/W

MBF

Dystric Cambisols

125

Złatna 17

U1200

1200/SE

HMCF

Lithic Leptosols

150

Jele¶nia

¦winna 186

J850

850/NW

MBF

Haplic Podzols

105

Kiełbasów 188

J650

650/SW

MBF

Dystric Cambisols

95

Sopotnia 18

J950

950/SE

MBF

Dystric Cambisols

95

Sucha Beskidzka

Wełcza 174

S850

850/N

MMBF

Dystric Cambisols

100

Roztoki 197

S1000

1000

MMBF

Haplic Podzols

105

Juszczyn

S1100

1100

MMBF

Dystric Cambisols

125

Andrychów

Łękawica 186

A450

450/NW

MBF

Dystric Cambisols

95

Roztoka 55

A800

800/NE

MMBF

Albi-Distric Cambisols

110

Sułkowice 154

A850

850/N

MMBF

Dystric Cambisols

115

Ustroń

Stawy

T900

900

MMBF

Dystric Cambisols

120

Czantoria 46

T800

800/SE

MMBF

Dystric Cambisols

105

Ustroń 5

T550

550

MMBF

Haplic Podzols

130

Dobka 24

T650

650

MMBF

Dystric Cambisols

150

HMCF - mountain coniferous forest high, MMCF - mountain mixed coniferous forest, MBF - mountain broadleaved forest, MMBF - mountain mixed broadleaved forest

The progress of the dendroscales reflects the history of increment reactions of trees to biotic and abiotic factors. This progress is usually fluctuatin in time, and it is burdened with a senile trend associated with formation of rings on a larger and larger circumference of the stem. In order to eliminate a long-term fluctuation of increments, as well as the senile trend, the dendroscales were subjected to indexing using the program ARSTAN [4]. In such a way a short-term variation of the ring widths, mainly depending on weather conditions was emphasized in the indexed dendroscales [3].

On the basis of the indexed dendroscales the indexed chronologies were developed for each study site. They represented the average annual increments of wood during consecutive years. The indexed chronologies were variables in the principal component analysis that was carried out using the computer program Statistika 6.0. The linear correlation and the coefficient of convergence (GL %) were used to determine the character of separated factors [5]. Looking for the influence of two main meteorological elements, i.e air temperature and precipitation, on diameter increment the method of linear correlation and multiple regression – the response function [10] was applied, using the program RESPO [14]. In this case the mean monthly values of air temperature and monthly sums of precipitation were the independent variables. While the mean increment indices of indexed chronologies of trees in three altitudinal zones were the dependent variables. The data obtained from the Żywiec meteorological station of the Institute of Meteorology and Water Management were used for the analyses.

To estimate the long-term changes in annual increments of wood the standardized chronologies were compared with the chronologies estimated on the basis of climatic data [14]. Only a senile trend was removed from the standardized chronologies retaining the long-term fluctuations of the tree-ring widths usually caused by environmental factors of a non-climatic character. To determine the level of homogeneity of increment reactions of trees in respective study sites the coefficients of convergence (GL%) between the dendroscales of individual trees were calculated. The degree of the progress similarity of dendroscales in each study site was expressed by the mean coefficient of convergence calculated for the period 1920–1960, and also for the period 1961–2001 when a rapid increase of air pollution occurred in Poland. While to estimate the similarity between increment reactions of trees of different study sites the coefficients of convergence were used according to the so-called stepwise method [ 8]. In this method, each time the mean coefficient of convergence between 25 site chronologies was calculated for the 10-year time intervals of the period 1900–2000. Besides the percentage of trees of a definite growth reaction (increase or decrease of the ring size in a given year in relation to the ring of the previous year) was calculated. The boundary value for the determination of signature years was 75% of trees of the same increment reaction [16, 22].

RESULTS AND DISCUSSION

In a given partial population the increment reactions of individual trees to meteorological factors are usually very close to one another, which results in a high similarity between dendroscales of the tree-ring widths of individual trees. This also concerns the chronologies of individual populations (site chronologies) occurring in the area of relatively homogeneous meteorological conditions (Fig. 1, 2). However, during the comparison made between the courses of these chronologies the periodic disturbances in the conformability of their courses, alternating with periods of a high conformability, may be observed (Fig. 1, 2). Especially high conformability of changes in the ring size from year to year was observed in the case of occurrence of particularly unfavourable or negatively optimal weather conditions in relation to requirements of a given species [10]. The years of such a type may be easily identified on the basis of the progress of chronologies of individual spruce populations (Fig. 1, 2). In most cases these were the signature years (Fig. 3). During the periods of higher frequency of occurrence of signature years there was also increase of the amplitude of changes in the ring size. This was particularly evident since the mid-1990s (Fig. 2, 3).

Fig. 1. Site tree-ring width chronologies of Norway spruce of 25 sites

Fig. 2. Site indexed chronologies of Norway spruce of 25 sites

Fig. 3. Percentage of trees increases their tree-ring widths during individual years. Signature years – black columns, number of trees – a line

The analysis of principal components of the indexed chronologies showed that the distinguished first three factors explained in total 73% of the total variance of chronologies. The first factor explained 57%, the second 11%, and the third one 5% of the total variance used in the analysis of variables. The dispersion of chronologies in relation to the factorial loads indicated that most of the chronologies strongly correlated with the first factor (Fig. 4, 5). The second factor differentiated the chronologies into three groups associated with altitude of study sites. The first group included the chronologies of sites situated between 450 and 750 m above the sea level, the second – the chronologies of sites located between 800 and 900 m, while the third group was made up of chronologies of sites situated above 950 m (Fig. 4, 6). It is interesting that in relation to the third factor the chronologies did not form d istinct groups (Fig. 5, 6).

Fig. 4. Dispersion of chronologies in relation to factorial loads

Fig. 5. Dispersion of chronologies in relation to factorial loads

Fig. 6. Dispersion of chronologies in relation to factorial loads

To identify the distinguished factors the analyses of convergence and correlation between the scores of individual factors and the air temperature as well as precipitation was carried out. It turned out that scores of the first factor attained the highest, statistically significant, convergence and correlation with the mean air temperature of the period February–April (GL=80.8 %, p<0.001; r=0.536, p<0.001); the scores of the second factor with the mean temperature of the summer period: June–August (GL=67.0 %, p<0.001; r=0.416, p<0.001); while the scores of the third factor were strongly negatively convergent and negatively corellated with sums of precipitation of September (GL=29.1 %, p<0.001, r= –0.256, p<0.05) (Fig. 7).

Fig. 7. Scores of the first factor (bold line) and the average temperature of the period February–April (upper figure), scores of the second factor (bold line) and the average temperature of the period June–August (middle figure), and scores of the third factor (bold line) and precipitation sums of September (lower figure)

Defining the first factor as the thermic conditions of late winter and early spring we may conclude that temperatures of that period had a strong and homogeneous effect on the variation of magnitude of wood increments of Norway spruce irrespective of the height above the sea level and slope exposure. Identifying the second factor as the air temperature of summer it may be assumed that this factor had a diversified effect on wood increment of trees growing at different altitudes. This may be the result of total heat decreasing with increase of altitude. Above 800 m the summer temperature becomes the factor limiting the rate of metabolic transformations, and in this manner it regulates the radial growth of trees. The effect of the third factor, identified as thermic conditions of September, may be interpreted in the following way: during the cloudless days of September the inflow of solar radiation to trees increases, and this makes the period of cambium activity longer. Similarly as the temp erature of summer this factor has a differentiating effect on increment reactions of trees. However in this case it is not connected with altitude or with exposure.

The results of the analysis of the principal components permitted to group the chronologies of Norway spruce populations into three main altitudinal zones: 450–750m, 800–900m and above 950m. We elaborated for each zone the mean indexed chronology, representing the relative magnitudes of radial increments of trees.

The results of the response function analysis confirmed the conclusions drawn from the principal component analysis. The coefficients of correlation and regression indicated that air temperature of winter and early spring (February–April) and temperature of summer (mainly in July) had a significant effect on wood increments of Norway spruce (Fig. 8). With increase of altitude the air temperature became the factor limiting more and more the size of radial increment of wood. At the highest altitudes a low temperature limited the growth during the entire summer season (June–August). Besides, a positive effect on size of wood increments at all altitudes had also high temperatures prevailing in October and December of the previous year (Fig. 8). A significant effect of precipitation on radial increment concerned mainly the summer period (June–July). The deficiency of precipitation during that period negatively affected activity of the cambium. Also a high precipitation of February and September had a positive effect on the wood increment of Norway spruce trees growing above 800m.

Fig. 8. Results of the response function analysis of chronologies of Norway spruce trees growing at altitude of 950–1200m (upper figure), 800–900m (middle figure), and 450–750m (lower figure) for the period 1920-1999. Coefficients of correlation – columns, coefficients of regression – line. Significant values at the 95% confidence limit – black columns and white circles, p – previous year

The coefficients of determination R2, calculated on the basis of coefficients of multiple correlation, were the measure of the effect of individual meteorological elements on the variation of magnitude of radial increments. The proportion of air temperature in variation of the ring widths of Norway spruce trees growing in the lowest zone of 450–750 m was 20%, in zone 800–900m - 26% and above 900m - 30%. The influence of precipitation on ring variation was the greatest in the “medium” altitudinal zone (R2=29%) (Fig. 8). A strong influence of meteorological elements on the metabolic processes responsible for radial growth was confirmed by a relatively high values of coefficients of determination R2 (44% – 49%), taking into account the total proportion of both temperature and precipitation in the variation of ring chronologies (Fig. 8). Trees growing at altitudes between 800 and 900 m are under the greatest influence of m eteorological conditions (R2=49%). In that zone severe thermic conditions prevail in winter, and there is deficiency of heat in summer. Besides the trees there are less privileged in respect of water accessibility from precipitation than trees growing higher up in zone of fogg and clouds. While above 800m trees usually grow on strongly skeletal soils of weak retention. Thus they have a smaller access to water resources than trees from lower altitudes.

A high quality of the regression models of the response function analysis describing relations between the size of radial increments of Norway spruce and thermic and pluvial conditions in respective zones were confirmed by courses of indexed chronologies conformable with chronologies estimated on the basis of climatic data (Fig. 9).

Fig. 9. Comparison of the indexed chronology (IND) and the estimated chronology of Norway spruce trees from three altitudinal zones; r – coefficient of linear correlation of chronologies

The analysis of a long-term progress of chronologies of the tree-ring widths showed a certain diversification. The standardized chronologies, from which only a natural senile trend was eliminated, and the chronologies estimated on the basis of climatic data showed almost identical progress only in the case of Norway spruce trees growing in the lowest altitudinal zone (450–750m). The higher altitude the grester were deviations from the course of both kinds of chronologies. The greatest drops in increment occurred in the case of trees growing above 950m during the period from the early 1970s to the mid-1980s (Fig. 10). Thus it may be supposed that in the past Norway spruce growing above 800 m was under a strong, long-term stress created by the factors negativelly affecting its condition. The weakening of trees was reflected in lowering of the metabolic processes responsible for the radial growth. The causes of the wood increment regress of Norway spruce should be looked f or in the effect of air pollution during that period. Its high level was a cause of lower wood increments, as well as a high mortality of trees of many species [1, 6, 7, 8, 9, 11, 12, 15, 17, 18, 20, 23]. When this stress receded in the mid-1980s a distinct process of revitalization took place in the case of Norway spruce trees over a hundred years old already. The most active reaction took place in the case of trees growing at the highest altitudes (above 950 m) (Fig. 10). The revitalization process was accompanied by an increasing susceptibility of trees most probably to the climatic factors. This susceptibility was expressed by very high amplitude of changes in the tree-ring widths occurring from year to year (Fig. 2). It shows that spruce trees have become susceptible to factors of a short-term character. The weather conditions undoubtedly are of such a character.

Fig. 10. Comparison of the standardized chronology (STD) and estimated chronology (EST) of Norway spruce trees from three altitudinal zones

The results of this study showed that the increment reaction of Norway spruce was different in respective study sites. However it was not associated with altitude or with exposure. In most localities the value of the mean coefficient of convergence (GL) for the period 1961–2001 decreased in comparison with this value for the period 1920–1960 (Fig. 11). While the homogeneity of average increment reactions of individual populations of trees increased as the age of trees increased (Fig. 12). The mean coefficients of convergence of site chronologies reached the highest values during the last 20 years of the 20th century (Fig. 12). The cause of this phenomenon seems to be a homogeneous reaction of trees to weather conditions occurring during the recent years. Lately they have become the dominant factor modelling the size of radial wood increments of Norway spruce in the area under investigations.

Fig. 11. Average coefficients of convergence (GL%) of the dendroscales for individual sites in two time intervals

Fig. 12. Average coefficients of convergence (GL%) between site chronologies during consecutive intervals. Boundary values of coefficients of convergence significant at the 95% confidence limit – red points

CONCLUSIONS

The thermic conditions of winter and early spring were a significant factor modelling in a similar manner the variation of size of radial increments of all Norway spruce populations. Low temperatures of February, March and April delayed the physiological activity of trees, thus lowering the wood increment. While a high temperature of the summer period had a positive effect on size of the annual wood increment. Also a high precipitation in February, June and July had a significant importance for cambial activity.

Three altitudinal zones: 450–750 m, 800–900 m, and above 950 m were distinguished on the basis of variation of the tree-ring widths. Trees in respective zones showed a different increment rhythm. Mainly the thermic conditions of summer were the factors differentiating the increment reactions of trees.

Norway spruce growing above 950 m had the greatest thermic requirements. Trees growing in a zone between 800 and 900m are under strong stress mainly because of the pluvial conditions.

Most probably the air pollution was a significant factor which weakened the biological activity of Norway spruce during 1970–1985, especially at higher altitudes.

Since the mid-1990s Norway spruce has shown the increse in average ring size as well as the increase in the amplitude of ring size changes. This reflects their increased susceptibility to meteorological stimuli of the environment, and may be the cause of their weakening and mass dying observed mainly at altitudes of 800–900 m.

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Sławomir Wilczyński, Edward Feliksik
Department of Forest Protection and Forest Climatology
Agricultural University of Cracow, Poland
e-mail: rlwilczy@cyf-kr.edu.pl,
rlfeliks@cyf-kr.edu.pl

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