BIOMASS AND ANNUAL PRODUCTION OF COMMON ALDER STANDS OF THE NIEPOŁOMICE FOREST

Stanisław Orzeł, Marcin Forgiel, Jarosław Socha, Wojciech Ochał
Department of Forest Mensuration, Agricultural University of Cracow, Poland

ABSTRACT

Biomass of stands of common alder (Alnus glutinosa (L.) Gaertn.) in the Niepołomice Forest is 120.97 (t.ha^-1) on the average. Almost 98% of this quantity is accumulated in the tree layer, while about 2% in the underbrush layer. Wood is the main part of biomass (about 80% on the average), especially wood of tree stems (69%). The percentage of the assimilative apparatus in biomass of stands is somewhat less than 2% (2.24 (t.ha^-1)), but it makes over 35% of the annual production of dry matter amounting to 6.156 (t.ha^-1) on the average.

Key words: common alder, stand, biomass, annual increment.

INTRODUCTION

Common alder (Alnus glutinosa (L.) Gaertn) is in Poland the only native forest tree species able to form dense stands on very moist soils [21], even in areas with stagnant water [12]. Thanks to symbiosis with bacteria Frankia alni alder is able to fix free nitrogen [16]. Forest communities formed by common alder are azonal in character.

Common alder is a fast growing species. Stands with its dominance in Poland covered almost 300 thousand hectares in 2001, i.e. 4.3% of the total area of state forests. Their volume was over 57 million (m³), i.e. 3.9% of the total growing stock of state forests [22]. Common alder was named "the tree of the year 2003" in Germany, and the symposium devoted to this species was organized in Burg in Spreewald [8]. This indicates that the increase of importance of this fast growing species should be expected in future. This seem to be confirmed by increased scientific interest in common alder observed recently. From among scientific works concerning dendrometry and production of this tree species, of a more general character, the growing stock tables [17], or growth models [4] are worth to be mentioned. Also the more detailed problems have been solved, such as volume tables [26], empirical formulae for calculating volume of merchantable and high class timber [10, 11], stand form factors [9], permanent height curves [3], stand quality curves [14], and analysis of height growth phases [2].

The problem of biomass of common alder stands have been discussed in works including papers of Johansson [13, 15] and Rieger et al. [24]. The present study also concerns this problem.

The objectives of this study were to estimate the quantity of biomass, and to determine changes in biomass and productivity of common alder stands of the Niepołomice Forest as they get older.

GENERAL ASSUMPTIONS IN CALCULATION OF BIOMASS AND BIOMASS PRODUCTION OF STANDS

Biomass of stands (BD) has been expressed in tons per area unit (t.ha^-1). It is composed of dry matter of the overground portion of trees (Bd) enlarged by dry matter of underbrush (Bp):

(1)

In biomass of trees the dry matter of the wood (Bdr), bark (Bk) and the assimilative apparatus (Bl) have been distinguished:

(2)

Biomass of stem wood (Bs) and biomass of branch wood (Bg) are the components of biomass of wood of trees (Bdr):

(3)

Biomass of wood and bark of trees has been calculated by converting their volume in a fresh state, as determined by dendrometric methods, to weight units in a dry state. Biomass of underbrush has been calculated according to the original method described in another paper of the authors [18, 19].

In production of stand biomass (Z_BD) only increment of the tree layer (Z_Bd) has been taken into account:

(4)

The increment of underbrush is an insignificant quantity in production of biomass of stands, and due to lack of an objective method of its calculation it is determined by estimation [20, 23, 24].

MATERIAL AND METHODS

Measurements of trees were carried out in 35 circular sample plots established in stands in which volume of common alder was more than 50% of the total stand volume. Such stands occupy the area of about 958 (ha) (9.5 %) of the forest area of the Niepołomice Forest [22]. The measurements were conducted under the project No P06L 013 22. Under this project a network of squares 500 (m) x 500 (m) was established in the area of the Niepołomice Forest District. In its nodes circular sample plots were established, 0.01 (ha) to 0.10 (ha) in size, depending on stand age. If there were less than 15 trees in the plot, then the plot area corresponding to stand age was enlarged by one order of magnitude. In sample plots, in stands over 10 years of age, dbh, height, double bark thickness, and 5-year dbh increment of all trees of dbh ≥ 7.0 (cm) were measured. On the basis of these measurements taxation characteristics of stands were determined.

Stem volume of measured trees, biomass of their branches and the assimilative apparatus were calculated using empirical formulae worked out for individual tree species [1, 5, 6, 7, 14, 25]. For common alder the following formulae were used.

Volume of stems with bark (in (dcm³)) was calculated by formula of Dik [7]:

(5)

where:
d - tree dbh
h - tree height
e - base of a natural logarithm.

The volume of stems with bark, calculated with formula (5) was reduced to volume of stems without bark:

(6)

where:

(72)

Variables g_zk and g_bk in formula (7) mean basal area of the tree with and without bark.

Volume of stem bark was calculated by subtracting volume of stem without bark (6) from volume of stem with bark (5).

Biomass of branches with bark (Bg) was calculated with formula:

(82)

Biomass of branches calcul;ated with formula (8)was divided into biomass of branch wood and biomass of branch bark keeping the same proportion as calculated for stems.

An analogical set of values was calculated on the basis of tree dimensions from before 5 years. This permitted in the next stage of calculations to determine the increment of dry biomass of wood and bark, separately for stems and branches.

Biomass of leaves (Bl) was calculated with formula:

(92)

Besides, in each plot, biomass of the underbrush layer was calculated.The description of these calculations have been presented in another paper of the authors [18, 19].

Height of trees measured in sample plots was the criterium for their allocation in one of the two layers (storeys) distinguished. The first storey included trees of height h ≥ 2/3 of mean height of 5 tallest trees in the plot. The remaining trees were assigned to the second storey.

² Formulae worked out by Dr. J. Socha on the basis of empirical material collected in common alder stands of the Niepołomice Forest by staff of the Dept. of Forest Ecology and Dept. of Forest Mensuration, Agricultural University of Cracow

RESULTS

Characteristics of stands

Age of stands investigated during this study varied widely from 5 to 111 years, while the stand quality (B) from 20.6 (m) to 49.3 (m) (Table 1). There were 300 to 5200 trees per hectare, including from 225 to 5200 of common alder trees. Pure alder stands occurred only in age classes I (a and b) and VI. In stands of the remaining age classes there was an admixture of oak, birch, ash, hornbeam, lime, pine, spruce, larch, elm, and mountain ash.

Average dbh of common alder in individual plots varied from 2.7 (cm) to 34.1 (cm), and its mean value increased in respective age classes. Basal area of stands varied from 2.54 (m².ha^-1) to 44.08 (m².ha^-1), and up to the age class IV its mean value was increasing. A similar regularity was observed in the case of stand volume. A wide range of stand characteristics resulted not only from differences in stand age, but also in site conditions. The mean percentage of common alder in total stand volume was 88.8%, and it varied from 56.1% to 100% in individual plots (Table 2). The mean percentage of admixture species was not high. Volume percentage of oak and birch was 2.5% (from 0.0% to 18.1%) and 2.1% (from 0.0% to 43.1%) respectively. This percentage for ash, hornbeam and lime was still over 1%, while the percentage of the remaining species jointly was 2.4%.

Biomass

Mean biomass for analyzed stands was 120.97 (t.ha^-1), and it varied in respective age classes from 11.96 (t.ha^-1) to 198.28 (t.ha^-1) (Table 3). Its essential part was made by trees of the storey I. Biomass of this layer in individual age classes varied from 8.79 (t.ha^-1) to 198.25 (t.ha^-1) (mean 112 (t.ha^-1)), and it made from 73.6% to 100.0% (mean 92.6%) of the total biomass of stands. Biomass of the storey II did not reach 10 (t.ha^-1) in any of the age classes, and its mean quantity of 6.41 (t.ha^-1) made 5.3% of biomass of analyzed stands. The percentage of underbrush in total biomass of alder stands in assumed age classes varied from 0.02% to 11.9% (from 0.034 (t.ha^-1) to 4.022 (t.ha^-1)), and it was 2.1% (2.492 (t.ha^-1)) on the average. In the layer of trees biomass of stems with bark was from 8.79 (t.ha^-1) (83.5%) in age class Ia to 170.26 (t.ha^-1) (85.9%) in class VI, biomass of branches with bark was from 1.27 (t.ha^-1) to 24.88 (t.ha^-1) (from 12.2% to 14.1%), and biomass of the assimilative apparatus was from 0.52 (t.ha^-1) to 3.10 (t.ha^-1). The percentage of wood in the biomass of the tree layer slightly increased with increase of age, the percentage of bark remained on a similar level, while the percentage of the assimilative apparatus systematically decreased from nearly 6.5% to 1.6% (Fig. 1).

Biomass of common alder made on the average 85.5 (48.7-100) % of biomass of the tree layer (Table 2). Its lower percentage in biomass than in volume resulted from a greater volume weight of admixture species.

Increment (production) of biomass

As it was assumed the increment of wood of stems and branches, increment of bark, and increment of the assimilative apparatus, were taken into account in estimation of the annual production of biomass. In the case of broadleaved species the biomass of leaves is at the same time the annual increment of the assimilative apparatus.

The percentage of common alder in the total biomass production was 83.8% on the average (from 38.9% to 100.0%), that of oak 3.6% (from 0.0% to 34.2%), birch 2.5% (from 0.0% to 47.3%), ash 3.5% (from 0.0% to 46.5%), and hornbeam 2.2% (from 0.0% to 16.8%). The percentage of any of the remaining species occurring in the tree layer was less than 0.9% of the annual production of analyzed stands (Table 2).

The annual increment of biomass in respective age classes (Table 4) varied from 1.709 (t.ha^-1) to 8.510 (t.ha^-1) (mean 6.156 (t.ha^-1)). The increment of stems was the main part of biomass production. Its percentage for individual stands varied from 42% to 68% (mean 56.0%), and generally it decreased with increase of stand age (Fig. 3). On the other hand the percentage of the increment of the assimilative apparatus in total production increased with increase of stand age. The increment of branches made from 8% to 10% of the annual production of biomass, and this percentage decreased with increase of stand age.

DISCUSSION

The occurrence of common alder in the Niepołomice Forest on sites of many different types, such as the moist mixed coniferous forest, mixed broadleaved forest, moist broadleaved forest, alder swamp forest, and ash-alder swamp forest, as well as a diversified species composition, are the main causes of a great variation of characteristics of analyzed stands, even within a single age class. This variation concerns mainly the stand volume which directly determines the quantity of biomass. The mean quantity of biomass, amounting to 120.97 (t.ha^-1), as calculated during this study, is by over 50% greater than that estimated 25 years ago by Rieger et al. [24]. At that time biomass of stands under discussion was determined on the basis of their volume assessed during the forest management plan preparatory work. Therefore the differences in methods are most certainly the main cause of such large discrepancies in results concerning the same study object. It is interesting, however, that there are no significant differences in quantity of annual production of biomass per area unit. Rieger et al. [24] estimated it at the level of 6.0 (t.ha^-1), while the mean quantity calculated during the present study is 6.156 +/- 0.398 (t.ha^-1).

The percentage of individual components of biomass of alder stands only slightly changes with their age. On the average almost 98% of its quantity is accumulated in the tree layer (Fig. 3), mainly in wood (80%), especially in wood of tree stems (69%). The percentage of the assimilative apparatus in total biomass of stands is not quite 2%, but it makes over 35% of their annual production (Fig. 4). Such a large difference between biomass percentage and production percentage of the assimilative apparatus resulted from the fact that in the case of broadleaved species the dry mass of leaves contributes to their annual increment of biomass as a whole.

The regularities in changes of the percentage of individual components in total stand biomass, found during this study, generally confirm results of studies carried out by Johanson in 10 stands of common alder growing on a former agricultural land in Sweden [15]. The greater differences concern the biomass quantity. The mean biomass of stands studied by Johanson was 38.8 ± 13.8 (t.ha^-1) (from 4.9 to 139.5 (t.ha^-1)), while their increment was 3.11 ± 0.68 (t.ha^-1.year^-1) (from 0.50 to 7.71 (t.ha^-1.year^-1)). Undoubtedly stand age, besides different growth conditions, is the cause of difference in quantity and increment of biomass. Johanson studied young stands only, 4 to 36 years of age.

The objective method of sampling applied during this study permits to refer its results to all common alder stands occurring in the Niepołomice Forest which fulfil the assumed criteria of species composition. Total biomass of these stands is 115 880 ± 10 926 tons, including wood biomass of the tree layer of 92 939 tons, biomass of tree bark of 18 411 tons, and biomass of the assimilative apparatus of 2 144 tons. Dry mass of underbrush is 2 387 tons. Annual production of biomass of the tree layer is 5 897 ± 381 tons, including wood increment of 3 191 tons, bark increment of 633 tons, and increment of the assimilative apparatus of 2 073 tons.

CONCLUSIONS

1. The percentage of wood in stand biomass slightly increases with increase of stand age, the percentage of bark remains stable, while the percentage of the assimilative apparatus decreases.

2. The underbrush layer does not significantly contribute to biomass of common alder stands, and its occurrence does not depend on stand age

3. The percentage of stem increment in biomass production of stands quite distinctly decreases with increase of their age, and the percentage of branch increment only slightly decreases. While the percentage of the assimilative apparatus distinctly increases with stand age.

4. The percentage of the assimilative apparatus of common alder stands in their annual increment is many times greater than in their total biomass.

REFERENCES

1. Braastad H., 1966. Volumtabeller for bjork [Volume tables for birch]. Meddelelser fra det Norske Skogforsoksvesen 21(1): 23-79 [in Norwegian].

2. Bruchwald A., Dmyterko E., Dudzińska M., Wirowski M., 2001a. Analiza faz wzrostu wysokosci olszy czarnej (Alnus glutinosa /L./ GAERTN.) [Analysis of height growth stages in black alder (Alnus glutinosa /L./ GAERTN.)]. Sylwan 1: 5-11 [in Polish].

3. Bruchwald A., Dmyterko E., Dudzińska M., Wirowski M., 2001b. Stałe krzywe wysokości dla drzewostanów olszy czarnej [Constant height curves for black alder stands]. Sylwan 11: 15-19 [in Polish].

4. Bruchwald A., Dudzińska M., Wirowski M., 2003. Model wzrostu dla olszy czarnej (Alnus glutinosa (L.) Gaertn.) [A distance-independent tree growth model for black alder (Alnus glutinosa (L.) Gaertn.)]. Sylwan 8: 3-10 [in Polish].

5. Bruchwal A., Rymer-Dudzińska T., Dudek A., Michalak K., Wróblewski L., Zasada M., 2000. Wzory empiryczne do określania wysokości i pierśnicowej liczby kształtu grubizny drzewa [Empirical formulae for defining height and dbh shape figure of thick wood]. Sylwan 10: 5-13 [in Polish].

6. Cerny M., 1990. Biomass of Picea abies (L.) Karst. in midwestern Bohemia. Scan. J. For. Res. 5: 83-95.

7. Dik E.J., 1984. Estimating the wood volume of standing trees in forestry practice. Rijksinstitut voor ondersek in de bos en landschapsbouw de Dorschkamp, Wageningen. Uitvoerige verslagen 19(1): 1-114.

8. Dmyterko E., 2003. Olsza czarna jako drzewo roku 2003 [Black alder - tree of 2003 year]. Pr. IBL, Ser. A, 3 (956-959): 115-116 [in Polish].

9. Dudzińska M., Bruchwald A., 2003a. Wzory empiryczne pierśnicowej liczby kształtu strzały w korze i grubizny drzewa dla drzewostanów olszy czarnej (Alnus glutinosa L.) [Empirical equations for the determination of bh form factor]. Sylwan 5: 36-41 [in Polish].

10. Dudzińska M., Bruchwald A., 2003b. Wzory empiryczne i tablice miąższości grubizny drzewa dla olszy czarnej (Alnus glutinosa (L.) GAERTN.) [Empirical equations and volume tables for the black alder (Alnus glutinosa (L.) GAERTN.) merchantable timber]. Sylwan 6: 69-78 [in Polish].

11. Dudzińska M., Bruchwald A., 2003c. Wzory empiryczne pierśnicowych liczb kształtu drewna użytkowego dla olszy czarnej (Alnus glutinosa (L.) Gaertn.) [Empirical equations for predicting merchantable breast height form factors for black alder (Alnus glutinosa (L.) Gaertn.)]. Sylwan 7: 3-6 [in Polish].

12. Jaworski A. 1995. Charakterystyka hodowla drzew leśnych [The characteristic of forest trees] Gutenberg, Kraków [in Polish].

13. Johansson T. 1999a. Dry matter and increment in 21- to 91-year-old common alder and grey alder and some practical implications. Can. J. For. Res., Vol. 29, 11: 1679-1690.

14. Johansson T. 1999b. Site index curves for common alder and grey alder growing on different types of forest soil in Sweden. Scand. J. For. Res., Vol. 14, 5: 441-453.

15. Johansson T. 2000. Biomass equations for determining fractions of common and grey alders growing on abandoned farmland and some practical implications. Biomass & Bioenergy 18: 147-159.

16. Krawiarz K., Chałupka W. 1980. Fizjologia wzrostu i rozwoju. (W:) Olsze. [Alders; Physiology of growth]. Warszawa-Poznań, PWN [in Polish].

17. Lockow K.W. 1995. Neue Ertragstafel für die Roterle [Yield tabels for common alder]. Wald, Jg. 45, 8: 268-271 [in German].

18. Orzeł S., Socha J., Forgiel M., Ochał W. 2005a. Struktura biomasy podszytu występującego w drzewostanach Puszczy Niepołomickiej [Biomass structure of the underbrush growing in pine stands of the Niepołomice Primeval Forest]. In press [in Polish].

19. Orzeł S., Socha J., Forgiel M., Ochał W. 2005b. Biomass of underbrush and conditions for its occurrence in stands of the Niepołomice Forest. Electronic Journal of Polish Agricultural Universities, Forestry. In press.

20. Orzeł S., Wysocki P. 2003. Struktura i przyrost biomasy wybranych drzewostanów sosnowych Nadleśnictwa Kłobuck [Biomass structure and increment in selected pine (Pinus sylvestris L.) stands of the Kłobuck Forest District]. Acta Sci. Pol. Silvarum Colendarum Ratio et Industria Lignaria 2(2): 61-70 [in Polish].

21. Pancer-Koteja E., Zarzycki K. 1980: Zarys ekologii. (W:) Olsze [Alders; Outline of ecology]. Warszawa-Poznań, PWN [in Polish].

22. Państwowe Gospodarstwo Leśne – Lasy Państwowe. 2001. Wyniki aktualizacji stanu powierzchni leśnej i zasobów drzewnych w Lasach Państwowych – na dzień 1 stycznia 2001 r. [A characterization of resources of State Forests of January 1st 2001]. Warszawa [in Polish].

23. Raimer J., Rutkowska L., Grabczyński S., Orzeł S., Rieger R. 1990. Ocena biomasy i produkcyjności drzewostanów kompleksu leśnego "Ratanica" na Pogórzu Wielickim. [Appraisal of biomass and productivity of "Ratanica" forest tract in Wieliczka Plateau]. Acta Agr. Silv., ser. Silv., 29: 89-103 [in Polish].

24. Rieger R., Grabczyński S., Orzeł S., Raimer J. 1984. Growing Stock and Increment of Tree Stands. (W:) Forest Ecosystems in Industrial Regions. Ecological Studies 49. Springer-Verlag Berlin Heidelberg New York Tokyo, 70-78.

25. Socha J., Wężyk P. 2004. Empirical formulae to assess the biomass of the above-ground part of pine trees. Electronic Journal of Polish Agricultural Universities, Forestry, Volume 7, Issue 2.

26. Thibaut A., Rondeux J., Claessens H. 1998. Tarifs de cubage pour l´Aulne glutineux (Alnus glutinosa (L.) Gaertn.) en Belgique meridionale. Rev. For. Fr., 3: 244-250. [Table of volume for common alder (Alnus glutinosa (L.) Gaertn.) in Belgium] [in French].

This study was carried out under the project No 3 P06L 013 22 entitled: "Biomass and annual production of woody vegetation of the Niepołomice Forest" financed by the Committee of Scientific Research.

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.