WOOD RADIAL CYCLIC HETEROGENEITY OF NORWAY SPRUCE (PICEA ABIES (L.) KARST.) DERIVED FROM RIPENING STANDS

Dieter Franciszek Giefing¹, Witold Pazdrowski¹, Stanisław Spława-Neyman², Tomasz Jelonek¹, Arkadiusz Tomczak^1
1 Department of Forest Utilization, University of Life Sciences in Poznań, Poland
² Department of Forest Utilization, August Cieszkowski Agricultural University of Poznan, Poland

ABSTRACT

The performed investigations aimed at determining the proportion of juvenile, maturing (transitory) and mature wood in the radial cross section of pine stems derived from the maturing stands of the II, III and IV age classes. The experiments comprised spruce trees from the areas of the southern distribution range of this tree species in Poland. The division into juvenile, maturing and mature wood was based on the proportion of late wood in annual rings.

Regularity was found to occur in the examined experimental material which consisted in the inversed proportionality of the width of annual rings and the proportion of late wood. In the case of older trees, the plotted curves describing the width of annual rings constituted nearly a mirror reflection of the curve characterising the proportion of late wood in the annual increments of trees for thickness. Results obtained for the radial cross sections of the youngest tree trunks (II age class) deviated quite distinctly from the above-mentioned principle.

Key words: juvenile wood, maturing wood, mature wood, wood cyclical heterogeneity.

INTRODUCTION AND RESEARCH OBJECTIVE

Forest trees are characterised by longevity and, therefore, stands made up from them, with the passage of time, go through a number of development stages affecting changes in the structure of individual trees and the wood tissue formed by them. When discussing the question of cyclical heterogeneity, it is necessary to distinguish between radial and axial heterogeneity.

The aim of this study was to make an attempt at analysing the radial variability of wood structure in which there are characteristic annual increments (rings) of differing width with a distinct zone of early and late wood.

In the course of the discussed experiments, the authors analysed the width of annual rings and the proportion of early and late wood on the cross section of tree stems derived from individual experimental surfaces as the basis for the identification of juvenile, transitory and mature woods.

Wood structure resulting from its phaseal growth is characterised by the occurrence in tree trunks of juvenile, maturing and mature wood. This problem was described in detail by Rendle [10]. Also Thörnqvist [16] as well as Haygreen and Bowyer [2] conducted investigations connected with this issue. The problem was also investigated thoroughly, among others, by such authors as: Raczkowski [9], Hejnowicz [3, 4], Pazdrowski [5], Pazdrowski and Spława – Neyman [6, 7, 8], Spława – Neyman [11], Spława – Neyman and Pazdrowski [12], Spława – Neyman, Pazdrowski and Owczarzak [13], Spława – Neyman and Wojcieszyn [14], Spława – Neyman and Szczepaniak [15].

The value of wood as well as the rational utilisation of the harvested wood raw material obtained in the course of the realisation of intermediate feelings is determined by the developmental phases of stands.

AREA, SCOPE AND METHODOLOGICAL ASSUMPTIONS OF RESEARCH

The experimental material was obtained from the area of the following forest districts: Szklarska Poręba – Wrocław Regional Direction of State Forests (RDSF) and Wisła – Katowice RDSF. In each of the districts, the experimental material for analyses was collected from stands of the II, III and IV age classes. Most of these stands derived from natural regenerations, partially supplemented with plantings.

Three model trees selected with the assistance of the dendrometric method (Urich II) were felled on each of the experimental surfaces. The selected trees – thick, intermediate and thin – occupied different biosocial positions and represented I, II and III Kraft class. A block of wood was cut out from each of the felled trees from the trunk section at the height of 1.3 to 2.0(m).

Within the framework of laboratory investigations, on the disks cut out from sample trees, the width of annual rings and zones of early and late wood in the consecutive annual thickness increments were determined.

An electronic increment meter coupled with a computer and a program called “Codima increment meter” were used for measurements.

On the basis of the width ratio of late wood to early wood, the character of the wood tissue (juvenile, intermediate mature) in tree stems was determined.

RESEARCH RESULTS

It is widely believed that the wood of coniferous trees of small thickness increments is characterised by better strength parameters than the wood of wide annual rings. Mature wood is characterised by relatively small width of annual rings (Figs. 1, 3, 5, 7, 9, 11, 13, 15 and 17) and a considerable proportion of late wood (Figs. 2, 4, 6, 8, 10, 12, 14, 16, 18). It is worth noticing that diagrams characterising increment widths usually constitute mirror reflections of diagrams describing the proportion of late wood in annual rings. Nonetheless, curves characterising trees of good biosocial positions derived from stands of the ll age class do not quite comply with this regularity (Figs. 1 and 2 representing predominating trees and 3 and 4 representing dominant trees). However, this fact by no means ruins the above-presented opinion, as the relatively poor stability of wood properties in the youngest stands is a well-known and accepted fact.

At the same time, it is worth paying attention to the course of increment curves of individual trees. Some of them were characterised by the highest thickness increments during the first growth phase (Szklarska Poręba Fig. 3 and Wisła Fig. 3). It is quite probable that these were the trees which were faced by no competition from their neighbours during this phase of their lives. This stimulated more dynamic thickness growth which was accompanied by the weakening of the height growth. The remaining trees (Figs. 1 and 5 – Wisła and Fig. 5 – Szklarska Poręba) showed small thickness increments during the first phase of growth. It is probable that they were growing in considerable density as a result of natural regeneration and this resulted in a dynamic height growth. These trees attained their maximum width of annual rings only after several years. When the stand reached crown closure, they were higher than the remaining trees; hence they occupied a better biosocial position which enhanced their further development. Also after achieving maturity, most of these trees continued to occupy good biosocial, i.e. dominant, positions.

Fig. 1. Width of annual rings of a predominant tree derived from the stand of the II age class

Wisła

Szklarska Poręba

Fig. 2. Proportion of late wood in annual rings of a predominant tree derived from the stand of the II age class

Wisła

Szklarska Poręba

Fig. 3. Width of annual rings of a dominant tree derived from the stand of the II age class

Wisła

Szklarska Poręba

Fig. 4. Proportion of late wood in annual rings of a dominant tree derived from the stand of the II age class

Wisła

Szklarska Poręba

Fig. 5. Width of annual rings of a codominant tree derived from the stand of the II age class

Wisła

Szklarska Poręba

Fig. 6. Proportion of late wood in annual rings of a codominant tree derived from the stand of the II age class

Wisła

Szklarska Poręba

Analysing the above figures, despite earlier remarks, it is possible to notice that, as a rule, the increase of the width of annual rings is connected with the decrease in the share of late wood.

It is worth noticing that in the case of trees occupying worse biosocial positions (III Kraft class), already in the ll age class, the diagram representing the magnitude of annual increments constitutes, approximately, a mirror reflection of the diagram characterising the proportion of late wood in annual rings.

Fig. 7. Width of annual rings of a predominant tree derived from the stand of the III age class

Wisła

Szklarska Poręba

Fig. 8. Proportion of late wood in annual rings of a predominant tree derived from the stand of the III age class

Wisła

Szklarska Poręba

Fig. 9. Width of annual rings of a dominant tree derived from the stand of the III age class

Wisła

Szklarska Poręba

Fig. 10. Proportion of late wood in annual rings of a dominant tree derived from the stand of the III age class

Wisła

Szklarska Poręba

In the case of Figures representing the experimental material from the Wisła Forest District, the observation that the magnitude of annual increments constitutes a mirror reflection of the share of late wood in annual rings is not corroborated in the examined first five annual rings. It can be presumed that this tree derived from natural regeneration and was strongly shaded during the first period of its life by neighbouring trees. It was not until the stand was opened up that this tree rapidly increased the size of its increments, most probably as a result of improvement in its biosocial position. This appears to confirm our earlier remark that wood properties of young, dynamically developing trees may differ from common opinions in this field.

Fig. 11. Width of annual rings of a codominant tree derived from the stand of the III age class

Wisła

Szklarska Poręba

Fig. 12. Proportion of late wood in annual rings of a codominant tree derived from the stand of the III age class

Wisła

Szklarska Poręba

In the case of all sample trees derived from the oldest stands represented by spruce trees of the IV age class, the regularity which was emphasised earlier becomes particularly apparent. Curves characterising the width of annual rings are inversely symmetrical to diagrams describing the proportion of late wood in annual rings on the cross sections of tree stems (Figs. 13–18).

Fig. 13. Width of annual rings of a predominant tree derived from the stand of the IV age class

Wisła

Szklarska Poręba

Fig. 14. Proportion of late wood in annual rings of a predominant tree derived from the stand of the IV age class

Wisła

Szklarska Poręba

Fig. 15. Width of annual rings of a dominant tree derived from the stand of the IV age class

Wisła

Szklarska Poręba

Fig. 16. Proportion of late wood in annual rings of a dominant tree derived from the stand of the IV age class

Wisła

Szklarska Poręba

Fig. 17. Width of annual rings of a codominant tree derived from the stand of the IV age class

Wisła

Szklarska Poręba

Fig. 18. Proportion of late wood in annual rings of a codominant tree derived from the stand of the IV age class

Wisła

Szklarska Poręba

The presented results indicate an inversely proportional relationship between the width of annual rings and the share of late wood. The widest increments were characterised by the smallest proportion of late wood.

In the case of juvenile wood, which is characterised by large increments, there is relatively little late wood characterised by good strength parameters. A considerable proportion of late wood in the narrow annual rings of older trees should increase the density of their wood and improve strength parameters.

DISCUSSION

The authors of this article focused their main research interest on investigating the following three wood zones on the radial cross sections of trees: juvenile, maturing and matured woods. This type of demarcation is fully justified in the majority of trees. However, there are trees for which it is not quite convincing because of the observed variability from standards in the proportion of late wood on the trunk cross section (Fig. 14 – Szklarska Poręba). According to the adopted principles, also here the division into the three above-mentioned wood zones was applied [1]. However, here the differentiation of wood properties in individual zones was not so explicit. The observation can be further developed and justified employing the analysis of increments and proportion of late wood in the annual rings of the examined trees.

When comparing the research results from individual trees, sample plots and forest districts, a number of regularities and differences can be noticed. Characteristic differences can be observed already at the stage of the assessment of the magnitude of annual increments. A review of the obtained research results allows distinguishing two groups of trees. The first of them is characterised by large increments in their youth which can be observed, most frequently, already from the first annual ring subjected to examination (Wisła Forest District – Fig. 3, 11, 13 and 14 and Szklarska Poręba Forest District – Fig. 1, 7 and 9). In the case of the second group, the increments are narrow in the zone adjacent to the pith but their width increases gradually and reaches its maximum between the 5^th and 20^th increment (Wisła – Figs. 1, 5, 7 and 9 and Szklarska Poręba – Figs. 5, 13, 15 and 17). It is to be presumed that in the first case, model trees were harvested in stands derived from plantings. In the second case, the assessed trees grew in less favourable conditions of development during the first period of their lives. Most probably, it resulted from the competition of the parent stand and natural seeding growing under strong crown closure. It was not until much later that these trees were able to take up favourable biosocial positions which allowed them to attain significant thickness increments.

Numerous results also indicate that the majority of trees, after attaining maximum growth expressed by the width of annual rings, gradually decrease their increment dynamics which can assume the form of continually decreasing width of annual rings (Wisła – Figs. 3, 5, 9, 11 and 15, Szklarska Poręba – Figs. 9 and 17) or, alternatively, fluctuate (Wisła – Figs. 1, 7, 11 and 13, Szklarska Poręba – Figs. 1, 2, 5 and 7), most probably, in response to changing growth conditions, i.e. biosocial position.

The above-described increment variability of trees can exert a significant impact on the possibility of assessment of the examined radial variability of wood structure which is not subject to any specific pattern but is an ontogenic character of individual spruce trees preconditioned by a number of external factors as well as genetic predispositions of both the species and individual trees.

The performed assessment of the structure of annual rings and the proportion in them of late wood in model trees allows describing relatively well the process of changes of wood characters on the radial cross sections of trunks. Model trees obtained from young stands can give results which contradict completely the existing regularities as exemplified by the model trees derived from stands of the II age class in Szklarska Poręba (Fig. 3) and trees from mature stands in Wisła (Fig. 13) and in Szklarska Poręba (Fig. 17) which reached the widest thickness increments only at the age of 20 – 30 years of age* (Wisła Forest District) and 10 – 20 years (Szklarska Poręba Forest District). Earlier, they were probably growing under canopy. Taking such trees for analyses can give results totally contradictory in comparison with the true spruce wood radial variability.

Also the proportion of late wood in annual increments which, when presented on diagrams, in mature trees constitutes almost a mirror reflection of the curve characterising the width of annual rings, in the case of young trees exhibits considerable variability. In the stands of the II age class, it is difficult to find the above-indicated regularity (Wisła – Figs. 1 and 2, 3 and 4 and Szklarska Poręba – Figs. 1 and 2, 3 and 4 as well as 5 and 6).

Observations presented here have a significant influence on the results of investigations of wood properties in individual developmental stages of trees and, therefore, it is essential to take them into account when interpreting the distribution of the obtained results in the course of studies concerning phase variability of wood properties on the cross section of trees.

CONCLUSIONS

1. Spruce wood is characterised by radial variability of the developing wood tissue referred to as cyclic heterogeneity of wood structure.

2. The width of annual rings in spruce decreases with the distance from the pith. This relationship is not of rectilinear character. Sometimes, we observe a transitory increase of the width of annual rings in trees which already produce mature wood and this phenomenon can be associated with thinning operations.

3. The observed variability in the radial distribution of widths of annual rings should be attributed to the strong response of spruce to changes in developmental conditions (thinning in the result of the removal of parental stand, sanitary thinning, natural disasters etc.).

4. The proportion of late wood in annual rings is inversely proportional to the width of rings. The graphic picture of changes in the proportion of late wood in annual rings on the radial cross section of wood constitutes almost a mirror reflection of the radial distribution of annual increments. This regularity was usually disturbed in young trees derived from stands of the II age class. This phenomenon was particularly visible in trees occupying better biosocial positions.

5. Bearing in mind a much more favourable radial distribution on the trunk of widths of annual rings and higher proportion of late wood in the case of spruce derived from naturally regenerated stands, this direction of management should be strongly recommended since it supports the production of more homogenous wood raw material of better strength properties and considerably broader possibilities of application.

REFERENCES

1. Giefing D.F., Pazdrowski W., Spława-Neyman S., Jelonek T., Tomczak A., Szczepaniak J., Kupczyk G. 2005, Niejednorodnosc cykliczna drewna swierka pospolitego Picea abies (L.) Karst. z drzewostanów przedrębnych a jego własciwosci techniczne [Wood cyclic heterogeneity of Norway spruce derived from maturing stands and its technical properties]. KBN 0440/P06/2002/23, Kat. Użytk. Lasu AR Poznań, ss. 146 [in Polish].

2. Haygreen J. G., Bowyer J. L. 1996. Forest Products and wood science. An introduction. Iowa State University, Press/Ames.

3. Hejnowicz Z. 1973. Anatomia rozwojowa drzew [Tree developmental anatomy]. PWRiL, Warszawa [in Polish].

4. Hejnowicz Z. 2002. Anatomia i histogeneza roœlin naczyniowych [Anatomy and histogenesis of vascular plants]. PWN, Warszawa [in Polish].

5. Pazdrowski W. 2004. The proportion and some selected physical and mechanical properties of juvenile, maturing and adult wood of black pine and Scots pine. EJPAU, 7(1), #3.

6. Pazdrowski W., Spława – Neyman S. 1993. Badania wybranych własciwosci drewna sosny zwyczajnej (Pinus sylvestris L.) na tle klas biologicznych w drzewostanie [Investigations of selected wood properties of Scots pine (Pinus sylvestris L.) against biological classes in the stand]. Folia Forestalia Polonica, seria B, zeszyt 24, 133–145 [in Polish].

7. Pazdrowski W., Spława – Neyman S. 1996. Macrostructure of Scots pine wood from unipres forest stands grown in conditions of dry forest. Folia Forestalia Polonica, seria B, zeszyt 27, 57–62.

8. Pazdrowski W. Spława – Neyman S. 2003. Stage growth of trees and its effect on selected properties pf Norway spruce wood (Picea abies (L.) Karst.). EJPAU, 6 (2), #2.

9. Raczkowski J. 1965. Badania nad niejednorodnosciš cyklicznš drewna rodzajów iglastych [Investigations on the wood cyclic heterogeneity of conifers]. Poznań [in Polish].

10. Rendle B. J. 1960. Juvenile and adult wood. Journal of the Institute of Wood Science, 5, 58–61.

11. Spława – Neyman S. 1994. Zmiany w budowie cewek drewna sosny zwyczajnej pochodzšcego z drzew wyrosłych w obszarach zagrożenia ekologicznego [Changes in the structure of wood tracheids of Scots pine trees derived from trees developed in ecologically threatened areas]. Reakcje biologiczne drzew na zanieczyszczenia przemysłowe, 1, 345–348, Kórnik 23–26 maja 1994. III Krajowe Sympozjum – materiały [in Polish].

12. Spława – Neyman S., Pazdrowski W. 1995. Macrostructure and selected properties of Scots pine (Pinus sylvestris L.) wood from the point of view of suitability for productions of composites. Proceedings of the Symposium Wood Modyfication 95. 2 – 4 August, Materiały konferencyjne Akademia Rolnicza Poznań, 224–234.

13. Spława – Neyman S., Pazdrowski W., Owczarzak Z. 1995. Wybrane biometryczne parametry budowy drewna sosny zwyczajnej (Pinus sylvestris L.) w aspekcie więzby sadzenia [Selected biometric parameters of wood structure of Scots pine (Pinus sylvestris L.) from the point of view of planting spacing]. Folia Forestalia Polonica, seria B, 26, 73–84 [in Polish].

14. Spława – Neyman S., Wojcieszyn A. 1995. Zagadnienia wykorzystania na cele konstrukcyjne drewna sosnowego pozyskanego z drzew młodszych klas wieku [Problems of utilisation for construction purposes of pine wood derived from trees of younger age classes]. Przemysł drzewny, 9, 18–20 [in Polish].

15. Spława – Neyman S. Szczepaniak J. 2000. Niejednorodnoœć cykliczna budowy drewna iglastego [Cyclic heterogeneity of coniferous wood structure]. XIII Konferencja Naukowa Wydziału Technologii Drewna SGGW, Warszawa [in Polish].

16. Thörnqvist T. 1993. Juvenile wood in coniferous trees. Document D13, Uppsala.

The paper was written on the basis of results obtained as a result of the KBN 0440/P06/2002/23 research project entitled: “Wood cyclic heterogeneity of Norway spruce [Picea abies (L.) Karst.] derived from ripening stands vs. its technical properties”.

* It is worth emphasizing that the analyses were carried out on tree samples collected from the breast height diameter. Spruce trees usually reach this height between the 5th and 10th year of life, depending on site conditions and occupied biosocial position

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Dieter Franciszek Giefing
Department of Forest Utilization,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 71A, 60-625 Poznań, Poland
Phone: +48 61 848 77 54
email: giefing@au.poznan.pl

Witold Pazdrowski
Department of Forest Utilization,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 71 A, 60-625 Poznań, Poland
Phone: (+48 61) 8487757
email: kul@au.poznan.pl

Stanisław Spława-Neyman
Department of Forest Utilization,
August Cieszkowski Agricultural University of Poznan, Poland
ul. Wojska Polskiego 71 A, 60-625 Poznan, Poland

Tomasz Jelonek
Department of Forest Utilization,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 71 A, 60-625 Poznań, Poland
Phone: (+48 61) 8487754
email: tjelonek@au.poznan.pl

Arkadiusz Tomczak
Department of Forest Utilization,
University of Life Sciences in Poznań, Poland
Wojska Polskiego 71 A, 60-625 Poznań, Poland
Phone: (+48 61) 8487754
email: atomczak@au.poznan.pl

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Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.

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