The study examines the population structure, vitality, and genetics of the English yew (Taxus baccata L.) in the Stiwoll Valley in Austria. It finds that the population has a high density of trees and high vitality. Genetic analysis shows high genetic variation. The population benefits from the diverse forest community that provides good growing conditions for yew. Ongoing monitoring is expected to provide information for managing yew populations in Austria.

1. 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 Introduction English 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 Method Fixed 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 = 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 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 stag ies as it was observed at the beginning of the monitoring. The trees of Taxus baccata (5 3 %) were dominating the mature stage together with Fagus sylvatica (2 3 %) and Picea abies (1 2 %) 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 (2 6 %) and Pinus sylvetris (1 5 %), 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 ( Ö OG) 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 (m 3 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. 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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. 1, 2, 3 or 4 <75 % < 30 % D (the least vital) 1, 2 or 3 < 75 % 30 – 50 % C (less vital) 1 or 2 75 - 90 % 50 – 70 % B (vital) 1 or 2 > 90 % > 70 % A (very vital) crowns formation* foliage density (%) living crown (%) Attributes Vitality class 62 81 8.8 6.3 17.3 3.20 2236 4.55 In total 63 79 8.9 6.6 17.9 2.99 779 1.76 No thinning 62 80 8.6 6.5 24.8 4.11 764 1.16 Moderate thinning 62 82 8.8 5.9 11.4 2.78 693 1.63 Intensive thinning ave. crown ( % ) ave. leaf density ( % ) ave. DBH (cm ) a ve. tree height ( m) tree volume (m 3 ha -1 ) basal area ( m 2 ha -1 ) Tree no ≥ 5 cm DHB Area ha Treatment 5.3.1.9 5 PGI-B Phophoglucose isomerase (Dimer) 2.7.5.1 4 PGM -A Phosphoglucomutase (monomer) 1.1.1.44 2 PGDH-A 6-Phosphogluconat-dehydrogenase (Dimer) 1.1.1.25 2 SKDH-A Shikimat-dehydrogenase (Monomer) 1.1.1.42 3 3 IDH-A IDH-B Isocitrat-dehydrogenase (Dimer) 3.4.11.1 3 3 LAP-A LAP-B Leucin-aminopeptidase (Monomer) 2.6.1.1 2 2 AAT-A AAT-B Aspartate-amino-transferase (Dimer) E. C. number Allele no Gene locus Enzyme [8] -- 0.168 0.172 -- 1.70 45.7 [4] -- 0.192 0.154 1.78 1.40 45 Taxus cuspidata [19] -- 0.308 0.302 1.45 -- [2] -- 0.350 0.316 1.48 2.62 -- [9] -- 0.419 0.429 1.37 2.83 61.11 In this study 69.60 0.312 0.286 1.45 2.90 90 Taxus baccata He Ho Ne A/L Polim loci P 95 (%) Different studies Hypo. gamete diversity Parameters Species Abies alba Larix decidua Picea abies Pinus sylvestris Taxus baccata Fagus sylvatica Other broad leaf species treatment vitality (%) very vital vital less vital least vital