Biodiversity of english yew (Taxus baccata L.) populations in Austria
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  • I going to present about the status of ------
  • I am going to present my paper in the following aspects
  • The map shows the world distribution of yew in different continents T. Baccata= Allover the Erope and Indian himalayan region, T.wallichi= Indian Himalayan region, T. Chinensis= China, T.Cuspidata= China and Japan, T.brevifolia= USA Canada, T. canadensis= USA , Canada, T. floridana= Florida USA, T.globosa= mexico, Guatemal, or central America
  • At present this species is declining most of its ranges, here I am presenting major cause of yew declination
  • The followings objectives are the major points of my PhD study
  • Here are some sample photographs of gel after gel electrophoresis
  • Each sample plot has 4 satellite sample plot in each sky direction for assessing the regeneration
  • Study of genetic variation is an important issues in the conservation and management of an endangered tree species, For this we also investigate the genetic variation of yew. For measurement the genetic variation we used-
  • Here are some sample photographs of gel after gel electrophoresis
  • Here are some sample photographs of gel after gel electrophoresis
  • Here are some sample photographs of gel after gel electrophoresis
  • Here are some sample photographs of gel after gel electrophoresis
  • Here are some sample photographs of gel after gel electrophoresis
  • Here are some sample photographs of gel after gel electrophoresis
  • Here are some sample photographs of gel after gel electrophoresis
  • Most interesting things is that there are certain high class of seedlings are missing
  • Decreasing the height differentiation and increasing the distance represent the better vitality class. Although it is statistically insignificant but it represent a trend how vitality influenced by the height differentiation and distance to neighbou
  • Ne= effective number of alleles
  • Here are some sample photographs of gel after gel electrophoresis
  • Here are some sample photographs of gel after gel electrophoresis
  • A big human exploitation has been take place in the 15 th centaury , population of Mond See is not older stand
  • A multi level approach is required to meet the demands of sustainable conservation strategies for yew populations in Austria During conservation planning an active participatory multi institutional involvement is needed to support local organizations in the implementation of forest conservation activities Public awareness programmes are needed to enhance the knowledge about the ecological importance of yew Continuous selective thinning will enhance the light availability which improves the population health condition for both pole stand and seedlings. Sound and professional harvesting operations is recommended which can reduce stem damages during tree felling The establishment of a fence in the studied gene conservation forests will help to observe the impacts of browsing on the regeneration. For studying natural population dynamics and long-term evolution the reproduction rate and sex ratio of the mature yew individuals has to be monitored More attention is needed for a better documentation of the role of birds and mammals that are responsible for seed dispersal T he regeneration status and the survival rate of yew individuals needs to be evalutated in 5-10 years cycles to allow sound recommendations for future conservation activities Further investigations are needed in other gene conservation forests in order to find the appropriate ecological requirements for the viability of yew populations in Austria It is necessary to investigate the optimum requirement of solar radiation for the seedling establishment which help to adapt the thinning activities accordingly . The Soil water relation is another important factor for reducing the survival rate of seedlings . So it should be checked. Investigations need to be extended in other gene conservation forests for assessing the regeneration status of yew all over the Austria. This will help to find out the actual causes about the shortcomings of certain height classes of seedlings. F urther investigations regarding the genetic structure are needed and more attention should be put on the number of samples as well as the sampling design Further investigations related to the possible impacts of climate change on different yew populations in Austria can help to enhance our understanding about the adaptation of the proper management activities for conserving the species

Biodiversity of english yew (Taxus baccata L.) populations in Austria Presentation Transcript

  • 1. 16/04/10 Biodiversity of English yew ( Taxus baccata L) populations in Austria PhD thesis presentation by A malesh DHAR
  • 2. 16/04/10
    • Contents
    • Background of Yew populations
    • Objectives
    • Methodology
    • Major Findings
    • Conclusions
    • Recommendations for monitoring and conservation management
    • Acknowledgements
  • 3. 16/04/10 Adapted from Salwasser (1991) Biodiversity of English yew
    • Communities / Ecosystem
    • Structure
    • Composition
    • Genetics
    • Variation between
    • and among populations
    • Species / Populations
    • Viability
    • Productivity
    • Recovery
    • Landscapes / Regions
    • Variety
    • Linkages
    Adult Yew Female Yew with fruits Male Yew with flowers
  • 4. World Distribution of Taxaceae 16/04/10 The circumpolar distribution of Taxus baccata and other Taxus species from Hultén & Fries (1986). + indicates interglacial records; indicates isolated occurrences; hatched areas indicate regions of common or fairly common occurrence. Broken lines outline the distribution of Taxus species other than T. baccata . Thomas P.A., Polwart A. 2003. Taxus baccata L. biological flora of the British Isles 229. Journal Ecology 91: 489–524 T.baccata T.brevifolia T.canadensis T.floridana T.globosa T.cuspidata T.chinensis T. wallichiana
  • 5. Causes of yew declination in Austria 16/04/10 16/04/10 Cause of Declination Competition for light Illegal logging lack of awareness Unfavourable site condition Lack of knowledge about management Historical reasons Herbivore susceptibility Loss of genetic variation Dioecious sexual system
  • 6. Research Objectives 16/04/10 3 . To estimate the level of genetic variation and diversity of Austrian yew populations at different geographic locations 1. To characterize the current ecological condition, population structure and regeneration of English yew in Austria 4 . To propose possible conservation and management strategies by using the Population Viability Risk Management (PVRM) framework 2. To compare the structural diversity of English yew populations for assessing the effects of inter-specific and intra-specific competition in relation to the viability of yew
  • 7. 16/04/10 Materials and Methods
  • 8. 16/04/10 Study populations in Austria Mondsee Bad Bleiberg Losenstein Hirschwang Piesting Stiwoll Almtal
  • 9. Materials and Methods – PVRM 16/04/10 Guideline for Population Viability Risk Management (PVRM) [ Adapted from Marcot and Murphy, 1996 ] Identifying the species at risk and relevant regulations Description of the ecological condition and genetic structure of the target species and their environment requirement for growth and development
  • 10. Materials and Methods: Ecological parameters 16/04/10
    • Data investigation all yew individuals DBH ≥ 5 cm
    • Tree height , Diameter at Breast Height (DBH), Crown length, Growth form, Crown foliage percentages, Vitality class, Height class, Damage
    • Experimental design
    • Plots on regular grid: 30 X 30 m for Stiwoll and Mondsee and 50 X 50 m for Bad Beliberg
    • Total no of plot: 48, 22 and 72
    Regeneration according to different height class and radius 151cm-4.9cm DBH 3.2 m Circle-3 31-50cm and 51-150 cm 1.6 m Circle-2 All seedlings, juveniles up to 30 cm 0.5 m Circle-1 Height class Radius Circle Data investigation of regeneration
  • 11. Materials and Methods – Structural Indices 16/04/10 Quantifying the Structural Diversity Three neighbouring trees of each individual male and female yew at each sample plot has been used to calculate following structural indices (Füldner1995) 35cm, 22m 20cm, 18m 22cm, 11m 2 nd Neighbour 3,5m 60cm, 32m 3 Neighbour Target tree yew 1 st Neighbour 1,5m 4,7m Height Differentiation DBH differentiation Distance to Neighbour Mingling Interpretation Calculated formula Attributes of stand structure
  • 12. Materials and Method- Genetics 16/04/10 Sample: Apical meristeme tissue (trees buds) Sample size: 624 (ranges from 40 – 122 per population) Genetic marker: Isozyme Enzyme system: 6 Laboratory procedure according to: Hertel (1996) and Konnert (2004) Data evaluation: GSED (Gillet 1998) and FSTAT (Goudet 2001) Following genetic parameters were assessed Polymorphic Loci (95%):(0.95 criterion: a locus is considered polymorphic if the frequency of the most common allele does not exceed 0.95, P >95 % ) A/L - average number of alleles per locus He - average expected heterozygosity= the estimated fraction of all individuals who would be heterozygous for any randomly chosen locus Ho- observed heterozygosity = No.of Heterozygotes at a locus / total no of investigated individuals hypothetical gametic diversity: the potential of a population for producing genetically diverse gametes [Dhar and Klumpp 2008]
  • 13. Materials and Methods - Genetics 16/04/10 Photographs of gel electrophoresis AAT PGM PGI IDH
  • 14. Materials and Methods – PVRM 16/04/10 Guideline for Population Viability Risk Management (PVRM) [ Adapted from Marcot and Murphy, 1996 ] Identifying the species at risk and relevant regulations Description of the ecological condition and genetic structure of the target species and their environment requirement for growth and development Development of conservation management alternatives
  • 15. Materials and Methods – PVRM, Development of Management Strategies 16/04/10 Dhar et al. 2008 ecophysiological characteristics of yew commentes influence on disposition slow growth The slow growth of yew reduces the capabilities to compete with other neighbouring tree species for resources which suppress the overall growth and development (Thomas and Polwart 2003). ↑↑↑ vegetative regeneration- c apacity A high vegetative regeneration capacity helps yew to survive after severe damages of trunk and crown and increases the overall chances for natural recruitment as well (Suszka 1978, Dhar et al. 2006). ↓↓ hard resistant wood Yew is slight susceptibility against wood rottenness after stem damages ↓ weak needles The needles of yew are intolerant to severe and prolonged frost (Skorupski and Luxton 1998) and icy wind (Bugala 1978) and do not protect against high transpiration rates (Leuthold 1980, Zoller 1981). ↑↑ shade tolerance of juvenile plants Seedlings can survive in low light intensity up to few years after germination, but light is an important factor for its growth and survival in the years to follow (Krol 1978, Boratynski et al. 1997, Thomas and Polwart 2003, Iszkulo et al. 2005, Iszkulo and Boratynski, 2006)) ↓ shade tolerance of adult plants An adult yew can survive in unfavourable light conditions for a long time (Lilpop 1931, Krol 1978, Brzeziecki and Kienast 1994). ↓↓ resistance to fire and abiotic damages A high resistance to fire and the high vegetative regeneration-capacity allows yew to survive intensive abiotic damages (Gilman and Watson 1994) ↓ high drought tolerance The high drought tolerance allows yew to overcome severe shortcomings in water availability (Gilman and Watson 1994, Thomas and Polwart 2003) ↓ dioecious sexual system The major advantage of a dioecious sexual system is the reduction of the inbreeding depression (Darwin, 1876). High levels of heterozygoty might be found even in small populations. Disadvantages are the loss of fitness via one or other sex function and the lack of mobility which can lead to extinction of small populations on the other hand (Charlesworth, 2001). ↑   susceptibility to diseases, pest and biotic damages Diseases are not a major concern although yew is notably susceptible to Phytopthera sp. root diseases (Strouts 1993) and ramorum dieback ( P. ramorum ) (Lane et al. 2004). Thomas and Polwart 2003 noted that big bud mite ( Cecidophyopsis psilaspis Nalepa: Eriophyidae) considered as a serious pest of yew in northern and central Europe. However, Taxus mealybug, black vine weevil, Taxus scale and can cause some damages (Gilman and Watson 1994). ↑ wide physiological amplitude Yew has a wide physiological amplitude which allows yew to spread out on a wide range of sites (Thomas and Polwart 2003) ↓↓ susceptibility to browsing and grazing Kelly (1981) ,Haeggström (1990), Mysterud and Østbye (2004) and Dhar et al. (2006) reported that yew is very susceptible to browsing and Watt (1926) pointed out that grazing can drastically affect the net growth rates which leads to strong negative effects on recruitment and adult survival in deer populated areas. ↑↑↑   General Importance of Ecophysiological characterstics of English yew with regards to risk suceptibility and viability of a population ( ↑ ) increase disposition (risk of extinction) ; ( ↓ ) decrease disposition (risk of extinction)
  • 16. Materials and Methods – PVRM, Development of Management Strategies 16/04/10 Dhar et al. 2008 Strategies for conservation management of English yew population natural + artificial natural + artificial natural natural natural natural Regeneration no no yes no no no Site Preparation no yes yes yes no no Careful harvesting no yes no no yes no Public awareness no yes yes no no no Selective thinning 50 % 30 % no 10 % 0 % no Thinning intensity no fence + game control fence no fence + game control no Wild Life Management V [timber production strategy] IV [conservation strategy] III [single tree selection] II [minimum strategy] I [wild life strategy] 0 [do nothing] Management Strategies Characteristic
  • 17. Materials and Methods – PVRM 16/04/10 Guideline for Population Viability Risk Management (PVRM) [ Adapted from Marcot and Murphy, 1996 ] Identifying the species at risk and relevant regulations Description of the ecological condition and genetic structure of the target species and their environment requirement for growth and development Evaluation of different management alternatives Development of conservation management alternatives
  • 18. Materials and Methods – Analytical hierarchy 16/04/10 Evaluation Hierarchy for viability of assesment of management strategies Dhar et al. 2006 Balanced structure Vitality Socio economic condition Maintenance Enhance Competition Risk Know how Acceptability Soil disturbance Light availability Risk Diseases Harvesting damage Browsing Inter Intra Damage during cutting Diseases Bark peeling Illegal cutting Management strategies Do nothing Minimum Conservation Timber production Wildlife Single tree selection Vertical st. Spatial structure DBH structure Investment Balanced structure Cont.prod.of seeds Genetic sustainability Vitality of pole stands Seedlings survivility
  • 19. Materials and Methods – PVRM 16/04/10 Guideline for Population Viability Risk Management (PVRM) [ Adapted from Marcot and Murphy, 1996 ] Identifying the species at risk and relevant regulations Description of the ecological condition and genetic structure of the target species and their environment requirement for growth and development Selection of a Management strategy Evaluation of different management alternatives Development of conservation management alternatives Implementation and Monitoring
  • 20. 16/04/10 Major findings
  • 21. English yew populations Structure in Austria 16/04/10 Regeneration status of Yew in three gene conservation forests Vitality of yew population in three-gene conservation forest DBH dristribution of English yew population in three gene conservation forests
  • 22. Structural diversity of English yew populations in Austria 16/04/10 Relation between the vitality class, tree-tree distance, and negative height differentiation for each yew from the structural group of four -1,00 -0,90 -0,80 -0,70 -0,60 -0,50 -0,40 -0,30 -0,20 -0,10 0,00 0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 distance [m] Height differentiation vitality-classes very vital vital less vital least vital [ ]
  • 23. Genetic consequence of English yew populations in Austria 16/04/10 Genetic variations of 7 yew populations in Austria [Dhar and Klumpp 2008] Population Size Gen. Mult. [M] Parameters P 95 (%) A/L Ne Hyp. Gam. Diversity Ho He Wright‘s Index [F] Bad Bleiberg 75 25 67 2.8 1.3 12.57 0.178 0.230 0.228 Stiwoll 109 25 100 2.8 1.4 17.26 0.232 0.267 0.124 Hirschwang 40 24 78 2.7 1.4 21.24 0.242 0.270 0.105 Piesting 62 23 67 2.6 1.4 27.72 0.260 0.279 0.066 Losenstein 122 24 78 2.7 1.4 31.98 0.272 0.299 0.089 Almtal 121 25 67 2.8 1. 4 21.50 0.228 0.267 0.149 Mondsee 95 22 78 2.4 1.4 42.60 0.257 0.304 0.155 Average 89 24.3 76.43 2.7 1. 4 24.98 0.238 0.274 0.131
  • 24. Genetic consequence of English yew populations in Austria 16/04/10 -- [Dhar and Klumpp 2008] Comparing genetic parameters for different studies on Taxus baccata in Europe 50-80 9-58 30 40-122 Sample size Taxus baccata Species 5 6 18 9 No of gene loci Tröber et al. (2004) 7.839 0.308 0.302 1.4   -- -- Cao et at. (2003) -- 0.316 0.340 1.48 2.62 (80.6) Lewandowski et al. (1995) 0.279 0.286 1.37 2.83 61.11 This study 24.98 0.274 0.238 1.37 2.7 76.43 He Ho Ne A/L P 95 (%) Different studies Hypo. gametic diversity Parameters Cluster diagram (UPGMA) based on the genetic distance (D0, Gregorius 1974) of seven populations in Austria Hirschwang Almtal Bad Bleiberg Piesting Losenstein Mondsee Stiwoll
  • 25. Findings – PVRM 16/04/10 Dhar et al. 2008 environmental characteristics of the present yew population relation to evaluation criteria effect on viability long term effects of management strategies (planning horizon 20 years) 0 I II III IV V huge number of yew 492 n ha -1 and the other trees species in total (959 n ha -1 ) leads to high inter specific competition --- --- --- + + ++ ++ causes moderate intra specific competition: - - - + + ++ ++ can increase the probability of demographic and genetic change processes and a high genetic sustainability ++ -- -- + + +++ +++ assures continuous recruitment by continuous production of seeds +++ + + ++ ++ +++ +++ causes a lack of light availability which has negative influences on assimilation, growth and strobilus development --- --- --- + + ++ +++ number of male and female individuals show a female biased sex ratio (1.56) which fosters continuous production of seeds as the dioecious sexual system needs a balances ratio of male and female +++ + + + + + + can increase genetic sustainability as the pollination is related to the distribution of male and female individuals ++ 0 0 ++ ++ +++ +++ 97.1 % of the yew population belong to the third tree layer and 2.9 % to the second layer which indicates gaps in the vertical structure of the population, yew is missing in the dominant height class -- -- -- + + ++ ++ a narrow diameter distribution and an average DBH of 8.8 cm limits population viability as a broad DBH structure is missing -- -- -- + + ++ ++ natural regeneration (> 30 cm height < 150 cm) is missing which hampers the balanced structure of the population, due to the absence of natural regeneration no supplement trees can build up the future population -- -- -/+ +/- +/- +++ +/- the very vital to vital condition of more than 79 % yew trees causes continuous production of seeds as good vitality indicates healthy condition ++ 0 + ++ ++ +++ ++ reduce the diseases susceptibility + 0 + + + ++ + supports the inter specific competition as it helps to compete with other tree species for growth and development + 0 + ++ ++ +++ ++ supports the intra specific competition as it increases the overall fitness of the population - 0 + ++ ++ +++ ++ socio-economic characteristics of the present yew population intensive harvest operation in conservation management cause soil disturbance which increase the likelihood of juvenile establishment + - - + + ++ +++ cause damages to the pole stand and increase vulnerability/risk for diseases -- + + - - - --- cause damages to the regeneration and increase vulnerability/risk for diseases - + + - - - --- low people awareness causes direct (illegal cutting) and indirect (browsing by game) human disturbances which increases the risk of illegal cutting - - ++ - - ++ - which increases the risk of browsing and leads to an absence of seedlings --- --- +++ --- --- +++ --- regulations according to Gene conservation forests increase public acceptability which reduces human pressures (illegal cutting, browsing) ++ -- ++ -- -- ++ -- causes investments as additional money is needed to maintain the viability of the gene conservation forest and income is reduced by conservation activities + + -- - - --- - Assesment of the current ecological state of the Yew population and their effect on management strategies for viability of the population
  • 26. Findings : PVRM 16/04/10 Overall priorities of management strategies for different scenarios Dhar et al. 2008 Management strategies 0- Do nothing, I- Wild life strategy, II- Minimum strategies, III- Single tree selection system, IV- Conservation strategy,V- Timber production strategy Scenarios A- Over all priority, B- Priority on genetic sustainability,C- Priority on vitality of pole stand, D- Priority on establishment and viability of seedlings,E- Priority on socio economic factors
  • 27. Conclusions o f the results 16/04/10 For regeneration Despite of adequate number of seedlings , yew showed shortcoming of certain height class this might be occurred due to the impact of browsing and competition for light
    • For pole stand
    • Most of the individual yews in Stiwoll (79%) and Mondsee (63%) are very vital to vital whereas in Bad Bleiberg it was less than 50%
    • The vitality of each individual yew is directly influenced by the inter-specific competition of the ir neighbouring tree species
    • Vitality is increasing with the increase of the tree-tree distance and the decrease of negative tree height differentiation
    • Genetic structure of pole stand
    • English yew populations in Austria showed a high level of genetic variation with a medium level of inbreeding effect .
    • Selected management strategy
    • Management strategy IV is combination of selective thinning, protection measures, game control with public relation activities is the most effective management alternatives
  • 28. Recommendations for monitoring and conservation management activities 16/04/10
    • Planning and management activities
      • a multi level approach is required
      • active participation of multi institutional involvement is needed
      • public awareness programmes are needed
      • continuous selective thinning is recommended
      • sound and professional harvesting operations are recommended
    • Monitoring activities
      • establishment of a fence is needed to observe the impacts of browsing on the regeneration.
      • reproduction rate and sex ratio of the mature yew individuals has to be monitored
      • more attention is needed for the role of birds and mammals
      • the regeneration status and the survival rate of yew individuals needs to be evaluated in 5-10 years cycles
    • Further research activities
    • further investigations are needed in other gene conservation forests
    • investigation concerning optimum requirement of solar radiation for seedling establishment is needed
    • the Soil water relation should be checked.
    • further investigations regarding the genetic structure are needed and more attention should be given on the number of samples as well as the sampling design
    • further investigations considering impacts of climate change on yew populations is needed
  • 29. 16/04/10 Acknowledgements For financial support ÖAD for North South Dialogue Scholarship, Landesregierung Steiermark, ÖOG for One world Scholarship I gratefully express my deepest sense of respect to my supervisor ao. Univ. Prof. Dr.Harald Vacik for giving me an opportunity to do my PhD studies in BOKU, as well as Ass. Prof. Dr. Raphael Klumpp for genetic studies. I would like to thank Univ.Prof. Dr. Holzner Wolfgang for examine my thesis. I am also giving thanks to Univ. Prof. Dr. Hubert Hasenauer, Head of Institute, and ao. Univ. Prof. Dr. Manfred Lexer, DI. Herwig Ruprecht, Ing. Monika Lex, and all Institute members for their support during my study period
  • 30. 16/04/10 A malesh DHAR Institut of Silviculture Department for Forest-and Soil Sciences University of Natural Resources ans Applied Life Sciences Peter Jordan-Str. 82, A-1190 Wien Tel.: +43 1 47654-4075, Fax: +43 1 47654-4092 Email: amalesh.dhar@boku.ac.at ,Web: www.boku.ac.at Thanks for kind attention
  • 31. Publications and conference presentations
    •  
    • Dhar A. Ruprecht H., Vacik H. 2008. Population Viability Risk Management (PVRM) for in-situ management of endangered tree species – a case study on a Taxus baccata L. population. Forest Ecology and Management, 255 (7) 2835-2845.
    • Dhar A., Ruprecht H., Klumpp R., Vacik H. 2007. Comparison of ecological condition and conservation status of English yew population in two Austrian gene conservation forests. Journal of Forestry Research 18 (3) 181-186
    • Dhar A. , Ruprecht H., Klumpp R., Vacik H. 2006. Stand structure and natural regeneration of English yew ( Taxus baccata L.) at Stiwollgraben in Austria. Dendrobiology, 56: 19 – 26
    • Ruprecht H.,Dhar A.,Aigner B., Oitzinger G.,Klumpp R., Vacik H (2008) Structural diversity of English yew ( Taxus baccata L.) populations. European Journal of Forest research (Revised version submitted)
    • Dhar A. , Klumpp R (2008) Genetic variation of English yew ( Taxus baccata L.) in the eastern Alps and their implications for conservation management. Ecological Research (under review)
    • Dhar A., Ruprecht H., Klumpp R., Vacik H. 2008. The Population Genetic Consequences for Conservation of an Endangered Taxus baccata L. population in Austria In: IUFRO Conference on Biodiversity in Forest Ecosystems and Landscapes from August 5-8, 2008 at Thompson Rivers University, Kamloops, British Columbia, Canada, p 41.
    • Klumpp R., Dhar A., Aigner B., Ruprecht H., Vacik H. 2008. Genetics and Population structure on an English yew gene conservation forest at foothills of the Eastern Alpine Mountains In: From the Mountain to Sea, Electronic PDF Abstracts, 22nd Annual meeting, Society for Conservation Biology from 13th to 17th July 2008, The University of Tennessee at Chattanooga, USA.
    • Dhar A., Ruprecht H., Klumpp R., Vacik H. 2008. On the structures and genetics of an Austrian relict population of English yew ( Taxus baccata L.). In: University of Cambridge (Eds.), Student Conference for Conservation Science, 9 th Student Conference for Conservation Science, 25-27 March 2008, University of Cambridge, Cambridge, UK. p 30.
    • Klumpp R. and Dhar, A. 2007. On the genetic variation of English yew ( Taxus baccata L.) throughout the Eastern Alps ( Untersuchungen zur genetischen Variation der Eibe ( Taxus baccata L.) im Ostalpenraum). Vortrag bei der 27. Tagung der Arbeitsgemeinschaft Forstgenetik und Forstpflanzenzüchtung, 10–13 October 2007. In: Anonymus 2007: “Forstgenetik -eine ökologische und ökonomische Zukunft gestalten.“ Tagungsband, BFW, Vienna, Österreich, p 3.
    • Dhar A., Ruprecht H., Klumpp R., Vacik H. 2007. Ecological condition and conservation status of Taxus baccata L. in an Austrian gene conservation forest. In: Society for Conservation Biology [Eds.], One World, One Conservation One Partnership, Electronic PDF Abstracts, 21st Annual meeting Society for Conservation Biology, 01-05 July 2007, Port Elizabeth, South Africa.
    • Dhar A., Ruprecht H., Klumpp R., Vacik H. 2007. Population structure, vitality and genetics of Taxus baccata L. at &quot;Stiwoll&quot; valley in Austria. In: Organization Committee of Ecosysummit 2007 (Eds.), Ecological Complexity and Sustainability – Book of Abstracts, p 64, EcoSummit 2007 - Ecological Complexity and Sustainability: Challenges and Opportunities for 21st-Century's Ecology, 22-27 May 2007, Beijing, China.
    • Ruprecht H., Dhar A., Klumpp R., Vacik H. 2007. Comparison of structural diversity of English yew ( Taxus baccata L.) populations. In: Organization Committee of Ecosysummit 2007 (Eds.), Ecological Complexity and Sustainability - Book of Abstracts, p 273, EcoSummit 2007 - Ecological Complexity and Sustainability: Challenges and Opportunities for 21st-Century's Ecology, 22-27 May 2007, Beijing, China.
    • Dhar A., Ruprecht, H., Vacik, H. 2006. Population viability risk management (PVRM) for in-situ management of a Taxus baccata L. population in Austria. In: Society for Conservation Biology-European Section [Eds.] Diversity for Europe, 1st European Congress of Conservation Biology 22-26 August 2006, Eger, Hungary. p. 106.
    16/04/10