Why this species
The West Himalayan Yew, Taxus contorta, is found through the Afghanistan Himalayas to Central Nepal. The main threat to the species is the collection of its leaves for medicinal use, as they contain precursors used in the manufacture of the anti-cancer drug Taxol. The sale of dried or fresh leaves to drug companies is a source of income and over collection poses a threat to the long-term health of the trees. In Nepal, populations are estimated to have undergone a recent decline of up to 80% due to harvesting for medicinal use and it is now Endangered in the wild. Furthermore, the leafy branches of this species are collected as animal fodder (unlike the European yew it is not toxic in low doses) and goats and cattle graze on shoots and young seedlings in the forests, stifling the species’ natural regeneration.
What are we doing about it?
GTC is working with the Royal Botanic Garden Edinburgh (RBGE), Nepal’s National Botanic Garden (NBG) and the Government of Nepal, Department of Plant Resources (DPR) to scale up conservation of yew’s in Nepal, including Taxus contorta.
Key activities include:
- Train DPR staff in field techniques for population assessment, data gathering and collection of seed and cuttings;
- Train NBG staff members in horticultural techniques for vegetative and seed propagation;
- Establish conservation collections at NBG;
- Collect scientific data on the distribution and extent of Taxus populations, past and present, and also prepare silica gel dried DNA samples and herbarium specimens for use in further research;
- Train staff members at DPR and NBG in conservation assessment techniques and produce global conservation assessments for Nepalese yews;
- Strengthen conservation on the ground through supportive local communities that are knowledgeable on the importance of the sustainable use of Taxus, and how to protect populations and increase natural regeneration/restoration.
Several populations of Taxus contorta within two different valleys in Manan Districts of Nepal have been surveyed. The healthiest population comprised over 1,000 individuals and showed clear signs of seedling recruitment. Seeds and cuttings from males and females were collected to be used to grow plants at NBG. RBGE delivered training to NBG staff on how to treat plant material brought back from the field and to share experiences of Taxus propagation at RBGE to maximise germination success.
Global conservation assessments for the three yew species (T. contorta, T. mariei and T. wallichiana) native to Nepal were updated at a Red List workshop. They were assessed as Endangered, Critically Endangered and Endangered respectively.