Population Structure Vitality and Genetics of Taxus baccata L.in “Stiwoll” Valley, Austria

Dhar A., Klumpp R., Ruprecht H. and Vacik H. Institute of Silviculture, Department of Forest and Soil Sciences, University of Natural Resources and Applied Life Sciences, Peter-Jordanstr. 82, A-1190 Vienna, Austria.,

*Corresponding author (amalesh.dhar@boku.ac.at)

t

IntroductionEnglish yew (Taxus baccata L.) is a slow-growing, long-lived, shade loving evergreen conifer tree species in temperate forests. It is scattered throughout Europe [1], northern Africa [15], the Caspian region of southwest Asia [11]. It has gained considerable importance as a source of anti-cancer drug and high aesthetic value of timber. At present it is a rare and endangered tree species in Austria [12] [14] [16] with restricted occurrence due to human activities, over uses in the past, browsing pressure by wild ungulates and unsuccessful regeneration [10] [17]. During the past 20 years spectacular progress has taken place in studies of genetic variation owing to the application of electrophoretic techniques to population genetics. Isozyme markers have been useful in many other aspects of forest genetics and they are particularly recommended for genetic diversity studies [5]. The “Stiwoll” valley can be found in the Eastern Alpine mountains (Fig.1). One forest compartment of this valley was identified as an Austrian “Taxus baccata gene conservation forest” in 2004 [6]. The main goal of this type of forest reserve is the in-situ conservation of rare tree species.

Objectives The objective of this study is to discuss the viability of the “Stiwoll” yew population regarding the structure of the forest community as well as the genetic structure of the local yew population.

Materials and MethodFixed sample plots (distance 30 x 30 m) were positioned for continuous monitoring of the yew population. Tree height, Diameter at breast height (DBH), crown length, foliage percentages, vitality, height class, and stem damage were scored from every yew tree sized with an DBH of more than 5 cm. The vitality was assessed by the percentages of the living crown, foliage density percentages and the crowns formation (Table 1) of each individual yew. Thinning operations were performed by the forest authority before starting the data investigation in order to find the best way of silvicultural treatment. Altogether, tree different levels of thinning were carried out: I) an intensive thinning (T I) by reducing 56 % of the standing volume, II) moderate thinning (T II) with a removal of 27 % of the standing volume and III) third no thinning (T III). Samples were taken from 109 yew trees for isozyme analysis during late autumn of 2006. The collected buds were stored at –81°C temperature.Labeling of the samples was identical with that used for measuring the metric traits. Horizontal starch gel electrophoresis was applied for separating the isozymes. Five enzyme systems were chosen for this study, which are known [7] to exhibit polymorphism in at least one of the encoding gene loci (Table 2). Electrophoretic procedures and staining protocols followed the methods described by others [3] [7].

X

Figure 1. Location of the study population of yew ( X )

Table 1. Classification scheme for the vitality assessment of Taxus baccata

1, 2, 3 or 4<75 %< 30 %D (the least vital)

1, 2 or 3< 75 %30 – 50 %C (less vital)

1 or 275 - 90 %50 – 70 %B (vital)

1 or 2> 90 %> 70 %A (very vital)

crowns formation*foliage density (%)living crown (%)

Attributes

Vitality class

(* 1 = very strongly developed crown, 2 = weakly developed,constricted crown 3 = undeveloped, most unilaterally, clamped crown, 4 = almost dying crown)

Table 2. Enzyme system used for electrophoretic analysis of the yew population

Table 3.Different chracteristics of English yew population according to treatment

62818.86.317.33.2022364.55In total

63798.96.617.92.997791.76No thinning

62808.66.524.84.117641.16Moderate thinning

62828.85.911.42.786931.63Intensive thinning

ave. crown

(%)

ave. leaf

density (%)

ave. DBH

(cm)

ave. tree

height (m)

tree volume

(m3

ha-1)

basal area (m2

ha-1)

Tree no ≥ 5

cm DHB

Area

haTreatment

TI = Intensive thinning, TII = Moderate thinning TIII = No thinning.

Figure 5. Vitality of yew population of the “stiwoll” valley

Results and Discussion Altogether, 15 different tree species were found at the gene conservation forest in the “Stiwoll” valley. Moreover, we observed a total of 2236 individual trees of English yew with DBH ≥ 5 cm. The Fig. 2 and Fig. 3 show the species composition of the total reserve for different stagies as it was observed at the beginning of the monitoring. The trees of Taxus baccata (53%) were dominating the mature stage together with Fagus sylvatica (23 %) and Picea abies (12 %) according to stem number per hectare (Fig. 2) and Fig 3 describe the species composition at young stage. But according to tree volume per hectare, Fagus sylvatica (35 %) is dominating the forest community, followed by Picea abies (26 %) and Pinus sylvetris (15 %), as demonstrated in Fig 4. This findings are not surprising as the top height of English yew in Europe is not expected to be more than 15 m. The top height of the dominating trees of the “Stiwoll” forest reserve was found at an average of 28.1 m whereas the top height of yew was 14.4 m on an average.Analysing the structure of the forest community at the “Stiwoll” valley revealed a very rich tree species composition (Fig. 2, 3 and 4). The significant number of yews (492 ha-1 at DBH ≥ 5 cm) shows good conditions for reproduction and growth in relation to other populations in Austria [6] [13] [18].For isozyme analysis 10 isozyme gene loci and 29 alleles were investigated. English yew showed high level of genetic variation with a mean number of alleles per locus (A/L) of 2.9, and 90 % of loci were polymorphic. When polymorphic loci were analyzed the average expected heterozygosity was estimated to be (He) 0.312 and mean observed heterozygosity (Ho) 0.286 respectively (Table 4). However, preliminary results indicated that there were no new alleles observed yet, compared to earlier studies of north European populations [7] [9].Having a closer look to those stand compartments, where the thinning operation was carried out, we found that yew exhibited comparable characteristics for each of the compartments (Table 3). Only the number of yew trees per hectare was highest in the compartment without treatment. Moreover, the analysis of the vitality of the single trees revealed the fact that there are no significant differences between the compartments of different silvicultural treatments (Fig. 5). The majority of the trees is classified as very vital (class A: 32,4 %) and vital (class B: 46,8 %) which means the vitality condition of the “Stiwoll” yew population (Fig. 5) is better compared to other studies of Austrian yew populations [20]. Hence, it can be concluded that experiment was carried out in a homogenous part of the stand. The future stand development of the different compartments will show, which treatment is best for the sustainable development of the yew population

Acknowledgement We would like to thank Ing. Schuster from local forest authority, Ing.Monika Lex for technical support during lab work and the Forest Province Office of Styria for financial support. We also thank the Austrain foreign exchange service (ÖAD) for financial support with the North South Dialogue Scholarship Program and the Österreichische Orient-Gesellschaft (ÖOG) for the One-World Scholarship.

Conclusion The English yew population of the “Stiwoll” valley has to be characterized by a high density of trees, a high level of vitality of the single individuals and a successful regeneration. Moreover the gene pool of yew exhibits high level of genetic variation. The species rich forest community of the submontane vegetation belt is obviously offering best conditions for the development of the yew population. Future monitoring of the “Stiwoll” population is expected to provide valuable results for the management of yew in Austria, in particular as genetic studies are included in the project

Figure 4. Species composition in respect of volume (m3 ha-1)

Figure 3.Species composition at young (DBH < 5 cm) stage according to tree number ha-1 Figure 2. Species composition at mature stage according to tree number ha-1.

Table 4 . Average Allozyme variation of different Taxus species in respect of different investigation

Figure 1. Location of the study population ( )

References[1] Bolsinger C.L., Lloyd J.D.,1993. Global yew assessment: status and some early result. In: S. Scher and Shimon B. Schwarzs child, eds. Intern. Yew Resources Conference: Yew (Taxus) conservation Biology and Intrections. Berkeley, Calif. Unpublished proceedings.[2] Cao Von C.-P., Leinemann M. Z., Finkeldy R. 2003. Study of the genetic variation and differentiation of yew (Taxus baccata L.)Stands using Isozyme and DNA Marker. Allg.Forst-u.J.Ztg.,1/2:21-28[3] Cheliak W.M., Pitel J.A., 1984.Techniques for starch gel electrophoresis of enzymes from forest tree species. Inf. Rep. PI-X-2, Petawawa Nat. For. Inst., Canadian For. Service., Agric. Canada.[4] Chung M.G., Oh G.S., Chung.J.M., 1999. Allozyme Variation in Korean Population of Taxus cuspidata (Taxaceae) Scand.J.Forest. Res. 14: 103-110.[5] Glaubitz J.C., Moran G.F., 2000.Genetic tools: the use of biochemical and molecular markers. In Forest conservation genetics. Principles and practice. CAB International, Wallingford, UK, p.39-59.[6] Herz H., Bernhard A., Nebenführ W., Slunsky R., Litschauer R., Heinze B.,2005. Das Eibenvorkommen in den Österreichischen Generhaltungswäldern. Poster bei der “12. Tagung der Eibenfreunde”, 2005 Sept 29 –Oct 2; Kempten in Allgäu.[7] Hertel H., 1996. Vererbung von Isoenzymmarkern bei Eibe (Taxus baccata L).Silvae Genetica 45:284-290.[8] Lee.W.S.,Choi W.Y., Kim W.W., Kim Z.S., 2000. Genetic variation of Taxus cuspidata Sieb et Zucc. In Korea. Silvae Genetica 49(3):124-130.[9] Lewandowski A., Burczyk J., Mejnartowicz L., 1995. Genetic structure of English yew (Taxus baccata L.) in the Wierzchlas Reserve:implications for genetic conservation. Forest Ecology and Management 1995 ;73:221-227.[10] Meinhardt H.,1996. Eibenvorkommen in Thüringen und Probleme Der Eibenverjüngung.In: Beiträge zur Eibe. Kölbel M, Schmidt O, (eds). Bericht aus der Bayerishen Landesanstalt für Wald und Forstwirtschaft ,10:04.[11] Mossadegh A., 1971. Stands of Taxus baccata in Iran. Revue Forestiere Francaise, 23 (6) 645-648.[12] Niklfeld H., 2005. (ed.). Rote Listen gefährdeter Pflanzen Österreichs. Grüne Reihe des- Bundesministeriums fur Umwelt, Jugend und Familie ,10.[13] Oitzinger G., 2000. Anwendung der qualitativen PVA (Population Viability Analysis) für die Evaluierung von Erhaltungsstrategien für ein Eibenvorkommen bei Bad Bleiberg/Ktn. Diplomarbeit an der Universität für Bodenkultur, Wien.[14] Russ W.,2005. Verbreitung seltner Holzgewächse nach der Österreichischen Waldinventur. BFW Praxis Information, 6:3-5.[15] Sauvage C.H., 1941. L’if dans le Grandatlas. Bull. Sci.Nat.du.Maroc, 21:82-90.[16] Schadauer k, Hauk E, Starlinger F., 2003. Daten zur Eibe aus der Österreichischen Waldinventur. Der Eibenfreund, 10:15-18.[17] Scheeder Th.1994. Die Eibe (Taxus baccata): Hoffung für ein fast verschwundenes Waldvolk. IHW-Verlag, Eching.[18] Tod F., 2004. Die Eibe und ihr Vorkommen im Bezirk Scheibbs (Niederösterreich). Eibentagung-Vortrag, http://homepage.univie.ac.at/franz.tod/eibenvork_bez_sb.htm(27.07.2005).[19] Tröber U., Paul M., Kahlert K., 2004. Genetic characterisation of English yew (Taxus baccata L.) in Thuringia and Saxony as basis for gene conservation. 11. Arbeitstangung von 20-22. September 2004 in Teisendorf, pp275-288.[20] Vacik H, Oitzinger G, Georg F., 2001. Population viability risk management (PVRM) zur Evaluierung von in situ Erhaltungsstrategien der Eibe (Taxus baccata L.) in Bad Bleiberg. [Evaluation of situ conservation strategies for English yew (Taxus baccata L.) in Bad Bleiberg by the use of population viability risk management (PVRM)]. Forstwissenschaftliches Centralblatt, 120: 390–405.

5.3.1.95PGI-BPhophoglucose isomerase (Dimer)

2.7.5.14PGM -APhosphoglucomutase (monomer)

1.1.1.442PGDH-A6-Phosphogluconat-dehydrogenase (Dimer)

1.1.1.252SKDH-AShikimat-dehydrogenase (Monomer)

1.1.1.4233

IDH-AIDH-B

Isocitrat-dehydrogenase (Dimer)

3.4.11.133

LAP-ALAP-B

Leucin-aminopeptidase (Monomer)

2.6.1.122

AAT-AAAT-B

Aspartate-amino-transferase (Dimer)

E. C. numberAllele noGene locusEnzyme

[8]--0.1680.172--1.7045.7

[4]--0.1920.1541.781.4045Taxus cuspidata

[19]--0.3080.302 1.45--

[2]--0.3500.3161.482.62--

[9]--0.4190.4291.372.8361.11

In this study69.600.3120.2861.452.9090Taxus baccata

HeHoNeA/LPolim loci P 95 (%)

Different studies

Hypo. gamete diversity

ParametersSpecies

12%

53%

2%7%

3%

23%

13%

29%

22%

36%

35%

14%

15%

3%7% 26%

Abies alba Larix decidua Picea abies Pinus sylvestrisTaxus baccata Fagus sylvatica Other broad leaf species

treatment

vita

lity

(%)

very vital vital less vital least vital

0

10

20

30

40

50

60

TI TII TIII In total