Amalesh Dhar, Harald Vacik, Herwig Ruprecht, and Raphael Klumpp Institute of Silviculture, Department of Forest and Soil Sciences, University of Natural Resources and Applied Life Sciences, Vienna Corresponding author (amalesh.dhar@boku.ac.at) 1. Introduction Population of slow growing long lived plants like English yew (Taxus baccata L.) typically received little attention in the past. Due to less interest, this species is now catalogued as a rare and endangered species in Austria as well as all over the Europe (Thomas and Polwart 2003). The reasons for declination of the yew are refer to the over use in the past centuries as well as unsuccessful regeneration, browsing pressure, illegal cutting and lack of appropriate management strategies (Svenning and Magard, 1999; Dhar et al. 2006b ). There are two general conservation strategies for slow growing long living species which are rare and endemic to small geographic areas. The first, most plans for management of such species have focused on land protection with the goal of protecting established individuals (Cardel et al.1997) and the second, the conservation efforts have focused on the reinstitution of the ecological process which is important to recruitment of new individuals. The goal of these efforts: to promote successful regeneration and increase the genetic diversity (Barrett and Kohn 1991). These two conservation strategies may not be sufficient by themselves if population of slow growing, long lived plants are predicted to be in long term declines (Kwit et al. 2004). The gene conservation forest network in Austria was developed as a programme to maintain the biodiversity of endangered species (Müller and Schultze 1998). Upto now 13 forests have been selected (Fig. 1 and Table 1) as gene conservation forests with a total area of 232,4 ha. The primary focus of these conservation category are the in-situ conservation of rare tree species by silvicultural treatments (Herz et al. 2005). There is a limited number of studies on the management of yew populations in gene conservation forests until now (e.g. Vacik et al. 2001; Dhar et al. 2006a). Here we try to find the possible cause on the yew declination and develop some recommendations for conservation and management of yew populations in Austria. Conservation of yew population On the basis of recent studies and the inventory of yew in different gene conservation forest following recommendation can be formulated for forest management and conservation for English yew populations in Austria- 1. Yew populations with a minimum size of 500 individuals should be dispersed or connected in the landscape to maintain the viability. 2. For controlling the browsing pressure, herbivory should be excluded from the forest by establishing fence (Dhar et al., 2006b) 3. Predation by rodents should be checked scientifically. 4. Appropriate light and micro climatic conditions (moderate crown closer of the upper story) are needed to maintain the yew population. To maintain the light availability a continuous selective thinning reducing the competition with other tree species is advocated to improve the status of yew population (Svenning and Magard, 1999; Dhar et al. 2006a). 5. Soil conditions should be taken into account as soil moisture can be an extremely limiting factor for seedling survival (http://www.ipgri.cgiar.org/publications/ pdf/1001.pdf ). 6. Genetic variation is of major importance for the survival of populations. In case of less variation artificial regeneration is essential. If the population size is small artificial regeneration could be an important way to increase the genetic variation. 7. Although English yew is a damage tolerant species, stem damage increases the susceptibility of other biotic infections. Yew is notably susceptible to Phytopthera sp. root diseases (Strouts 1993) and ramorum dieback (P. ramorum) (Lane et al. 2004). So, prevention (careful harvesting operations) is essential to avoid damage during tree felling. 8. People awareness will help to enhance the knowledge and ecological importance about yew (Vacik et al. 2001). Regular information and publications might help to increase the level of awareness and improve the overall knowledge about this species in the general public. 9. If yew trees need to be cut, it should be done 25 cm above from the ground as yew can produce more sprouting buds from that origin. 10. The success of yew regeneration should be evaluated by regeneration survey in 5-10 year cycles. Acknowledgement We would like to thank local forest authority and the Forest Province Office of Styria for financial support. We also thank to the Österreichische Orient-Gesellschaft (OOG) for the One- World Scholarship and the Society for Conservation Biology (SCB) for travel grant. Ecological condition and conservation status of English yew population in Austrian gene conservation forests Fig 1. Austrian map indicating with the geographic locations of different gene conservation forests 1 11 12 10 13 9 8 7 6 5 4 3 2 Table 1. Gene conservation forests in Austria (By BFW) Fig 2. Regeneration status of Taxus baccata population in Stiwollgraben and Leininger Riese 3. Competition for light One of the most important factors that can reduce the number of seedlings is an insufficient amount of light under the canopy trees. The yew is consider to be one of the most shade tolerant tree species in Europe (Thomas and Polwart 2003). It is also mentionable that almost 78 % of total saplings from Stiwollgraben were under the dense canopy (≥ 90 %) while in Leininger Riese it was only 43 % of total saplings. So a dense canopy has the negative effect on growth and survival of yew saplings (Svenning and Magard 1999). According to Iszkulo and Boratyński (2006) yew seedling can germinate and grow in very shady conditions but their light demand increase with the increase of age. So the total no ha -1 of saplings in Stiwollgraben was less then the total no ha -1 of adult, which justify the light requirements of yew saplings. 4. Loss of genetic variation Estimation of genetic variance for allozymes of plants within and among the population component can provide a basis for conservation of genetic diversity of plant programmes (Hamrick et al. 1991). These estimation of allozyme diversity can be used as effective decision tool of in-situ conservation measures for plant species. Regarding the English yew some scientist assumed the low level of genetic variation as suspected reason for decline. In general, coniferous tree species exhibit high levels of genetic variation. However there were few research were done in this field. In our study English yew population form Stiwollgraben showed high level of genetic variation (Table 4). 2. Illegal cutting and Low people awareness Illegal cutting is an important causes for English yew decline. It has gained considerable importance as a source of anti-cancer drug and high aesthetic value of timber. Its tough and long-lasting timber was extensively used for building and its high aesthetic appeal made it a popular decorative material from the Ancient time. 6. Dioecious sexual system and imbalanced sex ratio Dioecious sexual system increase biological expansion but constraints created by the lack of mobility. It will risk of extinction for smaller population. The major advantages of dioecious sexual system is reduce the inbreeding depression (Darwin, 1876). The disadvantage is loss of fitness via one or other sex function, (Charlesworth, 2001). Balanced sex ratio is highly potential for effective seed production. In our study we have found one case of balanced sex ratio (Leininger Riese ) and a second case of imbalance sex ratio (Stiwollgraben) (see Table 5). Table 5. Sex ratios of Taxus baccata population in Stiwollgraben and Leininger Riese 5. Adverse soil condition Soil water relation is an important limiting factors. It can be an extremely reducing factor for the seedling survival (http://www.ipgri.cgiar.org/publications/ pdf/1001.pdf ). 1. Herbivore susceptibility and Seed predation by rodent Despite of its poisonous properties yew is very vulnerable to browsing and bark stripping by rabbits, hares, deer and domestic animals such as sheep and it is effected by rodent predation (Kelly 1975; Haeggström 1990, Dhar et al. 2006b). Indeed T. baccata is one of the grazing sensitive trees (Kelly, 1975) and there is a strong negative effect on recruitment and adult survival if the deer population is high (Kelly, 1981;Mitchell, 1988). Similarly, T. Canadensis Marsh. is declining in abundance in the Great Lakes region due to heavy deer browsing (Gill et al., 1995). In our study it was observed that there were no any sapling in the height class of 30 to 50 and 51 to 150 cm in Stiwollgraben and 51 to 150 cm Leininger Riese (Fig. 2). Loss of Tree species Risk of Extinction Table 4. Average Allozyme variation of different T. baccata in respect of different investigation Table 3 . Status English yew population in Stiwollgraben and Leininger Riese in respect of different age class The Major causes for the decline of yew resources 1.Herbivore susceptability & Seed predation by rodent, 2.Illegal cutting and Low people awareness, 3.Competition for light, 4. Loss of Genetic variation 5. Adverse soil condition, 6. Dioecious sexual system & imbalanced sex ratio Research sites Among 13 Yew gene conservation forests (Fig. 1 and Table 1) a full investigation of “Stiwollgraben”, " Leininger Riese " and a partial investigation of “Losenstein”, “Almtal” and “Pichlwald” respectively were completed. The major causes related to yew decline in 5 gene conservation forests are given in Table 2. Site Total no of individuals Female Male Undefined (sex) Ratio(sex) Leininger Riese 828 392 432 3 0.91 Stiwollgraben 2236 835 535 866 1.56 Name of the Province and location Name of the site Total area [ha] Altitude [m] Total no of Yew 1. Vorarlberg Rohrach 48.0 480 – 720 ---- 2. Tirol Hinterstein 28.4 900 – 1.050 ---- 3. Tirol Schanzer Wänd 46.9 480 – 720 ---- 4. Upper Austria Pichlwald 2.6 480 – 530 244 5. Upper Austria Almtal 3.2 460 – 490 > 2000 6. Upper Austria Losenstein 39.6 540 – 680 1815 7. Lower Austria Rastkreuz 9.8 800 – 950 ---- 8. Steiermark Stiwollgraben 4.6 580 – 700 2236 9. Kärnten Launsdorf 1.0 620 – 660 ---- 10. Kärnten Gotschuchen-Schloßberg 5.9 900 – 980 ---- 11. Kärnten Bad Vellach 2.0 900 – 950 ---- 12. Kärnten Eisenkappel 3.0 760 – 820 --- 13. Kärnten Leininger Riese 18.5 900 - 1300 828 Site Area [ha] Density Ave. canopy closer for Saplings < 5 cm DBH with standard deviation (SD) [%] Total Seedlings ≤ 2 years age Saplings > 2 years age Adults ≥ 5 cm DBH no. ha -1 no. ha -1 no. ha -1 no. ha -1 Stiwollgraben 4.6 15608 14699 417 492 95 (+ / -18) Leininger Riese 18.4 2805 2096 664 45 80 (+ / -17) Major causes related to yew declination Gene conservation forests Conservation strategies Stiwollgraben Leininger Riese Losenstein Almtal Pichlwald Browsing by herbivore present present present low medium 2,3 Competition for light High High High High High 4 Lose of genetic variation Not found Under investigation Under investigation Under investigation Under investigation 6 Illegal cutting present present absent present absent 8 Abiotic damage present present present present present 7,9 Biotic damage (gall mite) Not found present present present present Low people awareness yes yes yes yes no 8 Seed predation by rodent Not measured Not measured observed Not measured Not measured 3 Species Parameters Hypo. gamete diversity Literature Polim. loci P 95 (%) A/L Ne Ho He Taxus baccata 90 2.90 1.45 0.286 0.312 69.60 In our Study 61.11 2.83 1.37 0.429 0.419 -- Lewandowski et al. 1995 -- 2.62 1.48 0.316 0.350 -- Cao et al. 2003 -- 1.45 -- 0.302 0.308 -- Tröber et al. 2004 Table 2. Causes related to yew population in five different Austrian gene conservation forests 1368 728 296 308 0 60 13018 1680 280 0 0 137 1 10 100 1000 10000 100000 Seedlings 2 ys > 2ysp 30-50 cmh 51-150 cmh >151cmh growth stages individuals [n ha -1 ] Leininger Riese Stiw ollgraben 2ys = years seedlings, >2ysp = >2 years seedlings, >151cmh = > 151 cm height and < 5 cm DBH In-situ conservation References: Barrett, S. C. H., and Kohn, J.B. 1991. Genetic and evolutionary consequences of small population size in plants: implications for conservation. Pages 3-30 in D.A. Falk and K.E. Holsinger. Editors. Genetics and conservation of rare plants. Oxford University Press, New York. Cardel, Y., Rico-Gray, V., Garcia-Franco, J.G. and Thien, L.B. 1997. Ecological Status of Beaucarnea gracilis, an endemic species of the semiarid Tehuacan Valley, Mexico. Conservation Biology 11: 367- 374. Darwin, C.R.1876. 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