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Description |
Geographic Range [top]
Range Description:
This species is found in China (SE Xizang [Tibet], NW Yunnan, S Sichuan), E Nepal, Bhutan, India (Arunachal Pradesh, Assam), Myanmar [Burma], Viet Nam (only known for certain from Lam Dong (Duc Trong, Xuan Tho, Don Duong, Lac Duong), Malesia, Philippines, Sulawesi and Sumatera.There is also one specimen record from northeast Thailand that dates back to 1931; since then it has not been recollected (Somran Sudee, Rachun Poona, Bangkok Forestry Herbarium, pers.comm.). It may also occur in Lao PDR.
The extent of occurrence is well beyond 20,000 km2. Its area of occupancy is also likely to be more than 2,000 km2.
Countries occurrence:
Native:
Bhutan; China (Sichuan, Tibet [or Xizang], Yunnan); India (Arunachal Pradesh, Assam, Sikkim, Uttar Pradesh); Indonesia (Sulawesi, Sumatera); Myanmar; Nepal; Pakistan; Philippines; Viet Nam
Additional data:
? Continuing decline in area of occupancy (AOO): Yes
? Extreme fluctuations in area of occupancy (AOO): No ? Estimated extent of occurrence (EOO) - km2:
Range Map: Click here to open the map viewer and explore range.
Population [top]
Population: Taxus wallichiana is very widespread but subpopulations within that range are often disjunct and isolated. The global population has undergone a major decline within the last 25 years which is still continuing
Current Population Trend: Decreasing
Additional data:
? Continuing decline of mature individuals: Yes
? Extreme fluctuations: No ? Population severely fragmented: Yes
Habitat and Ecology [top]
Habitat and Ecology: Taxus wallichiana is a small to large understorey or lower canopy tree in montane, temperate, warm temperate, and tropical submontane to high montane forest, both angiosperm and conifer dominated, deciduous or evergreen, or in mixed forests. In open situations on rocky slopes and cliffs it usually forms a large, broadly spreading shrub. Elevation ranges from 900 m to 3,700 m asl and soils are mostly derived from silicate-bearing rocks, i.e. acidic to neutral. Like the European T. baccata it is easily dispersed by birds and can germinate quickly in large numbers on suitable sites. It has a very long life-span and may sprout from stumps. Taxus wallichiana occurs in pure stands of limited extent or mixed in the understorey of Quercus, Abies and Picea, or in mixed conifer forest. In Viet Nam T. wallichiana has been found growing in submontane evergreen mixed forests associated with the conifers Cephalotaxus mannii, Dacrycarpus imbricatus, Keteleeria evelyniana, Nageia wallichiana, and Podocarpus neriifolius. It will form dense thickets on exposed rocky slopes with little tree growth. In the Philippines it occurs on high ridges and mountain summits in mossy forest, or sometimes in rocky grass and scrubland. In Sumatera and Sulawesi it is usually a mid-montane species.
Systems: Terrestrial
Continuing decline in area, extent and/or quality of habitat: Yes
Generation Length (years): 30
Use and Trade [top]
Use and Trade: The wood of Himalayan Yew is durable and strong and is used for door frames, cabinet work and wood turning and wood inlaying, also for candlesticks, knife handles etc. Less refined products are gates and fences, poles, struts and wattle and daub in walls of rural buildings. The wood is also burnt as incense in Nepal and parts of Tibet. In other areas the wood is used as fuel. The leaves are toxic but can be given as fodder to goats if no other foliage is available. The alkaloid compounds (taxanes) of the bark are a source for the anti-cancer drug paclitaxel (Taxol®) which has become a major reason for exploitation in recent years. The leaves yield similar chemicals in low concentrations. Traditional medicine has made use of young shoots and leaves and sometimes of inner bark for a long time in various potions, tinctures, and pastes. The only non-toxic part of yews, the fleshy aril around the seed, is consumed by local inhabitants as jams. The inner bark also produces a red dye, often used in religious ceremonies by Brahmins of Nepal (Singh 2007). Since the exploitation of Himalayan yew for its foliage containing taxanes has proved to be unsustainable, cultivation efforts are being undertaken in the Himalayan foothills and elsewhere in India; this involves both species T. contorta and T. wallichiana. These species, because of their similarity with European Yew (T. baccata), are rarely found in cultivation in Europe, but they are used as ornamentals elsewhere, as in Baguio, Philippines.
Threats [top]
Major Threat(s): Across most of its range through the Himalayas and western China, Taxus wallichiana has been heavily exploited for its leaves and bark which are used to produce the anti-cancer drug paclitaxel or similar chemicals. Declines of up to 90% have been reported in India and Nepal while in western China declines of more than 50% have been reported. The degree of exploitation in Myanmar is uncertain. In Viet Nam the subpopulation is limited to several hundred trees within a very limited area of Lam Dong Province. This remnant subpopulation was more extensive in the recent past but has declined due to deforestation and conversion of forests for agriculture. The status of Taxus populations in the Philippines and Indonesia is less clear. Some reports of exploitation associated with taxol production have come from the Philippines (Agillion 2007) but these have not been well documented. Although the Philippines has lost the vast majority of its forest cover through logging and agricultural expansion, the degree to which this has effected Taxus is unknown and ground truthing of both recent and historic records is needed. In Sulawesi and Sumatera widespread deforestation has been concentrated in the lowlands rather than the montane areas where estimates of decline are as low as 5% (Cannon et al. 2007, Laumonier et al. 2010). As with the Philippines further field work is required to ascertain the status of Taxus in these areas
Conservation Actions [top]
Conservation Actions: Taxus wallichiana is listed under CITES Appendix II. It occurs in several protected areas, e.g. the Sagarmatha National Park in Nepal and BiDoup-NuiBa National Park in Viet Nam. Cultivation on a large scale in the context of pharmacology could reduce the pressure on wild populations in the future. In the short term this species continues to be over-exploited throughout much of its range. In Viet Nam a propagation program has been started to establish clonal banks in Lam Dong so that this species may be conserved and utilised for Taxol production in the future.
Citation: Thomas, P. & Farjon, A. 2011. Taxus wallichiana. The IUCN Red List of Threatened Species 2011: e.T46171879A9730085. http://dx.doi.org/10.2305/IUCN.UK.2011-2.RLTS.T46171879A9730085.en. Downloaded on 25 January 2017.
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