Seeds of Vietnamese golden cypress plants have been successfully grown for the first time at Bedgebury National Pinetum and Forest, providing hope for the dwindling population in the mountains of northern Vietnam.
For the first time ever, plants of the Endangered Vietnamese golden cypress have been successfully grown from seeds, at Bedgebury National Pinetum and Forest, managed by Forestry Commission England. All the current ex situ collections worldwide have been grown from cuttings of trees in the wild, making them clones. These seed raised plants hold more genetic diversity, something which is key to the recovery of species with dwindling populations. It is hoped these plants can be transported back to Vietnam within the next two years and used to directly increase the wild population.
The Vietnamese golden cypress or Xanthocyparis vietnamensis is the most recently discovered conifer, found in low numbers in northern Vietnam in 1999. The tree is found in severely fragmented populations in the wild and is confined to the top of mountain ridges, making it susceptible to climate change. It is thought this species was originally more widespread, with selective timber extraction the biggest cause of its decline. Additional surveys in China in 2014, supported by the Global Trees Campaign, found 17 new individuals of this species: 15 adult trees and 2 seedlings. This indicates that the trees are capable of regeneration in the wild. This discovery brings the total number of known trees in China to 18. In addition to this, a
Additional surveys in China in 2014, supported by the Global Trees Campaign, found 17 new individuals of this species: 15 adult trees and 2 seedlings. This indicates that the trees are capable of regeneration in the wild. This discovery brings the total number of known trees in China to 18. In addition to this, a GTC survey found 15 mature trees in Vietnam, 70km away from the original population of between 500 and 1000 individuals. Despite finding these individuals, the population remains critically low and requires further support from ex situ collections.
The successful propagation of this species from seed has been a long time in the making. It was back in 2008 when members of Bedgebury National Pinetum were invited by the Global Trees Campaign to visit a nursery in northern Vietnam, with the idea of collaborating on the GTC project, which was looking to work with experts in conifer propagation.
Bedgebury Pinetum’s Dan Luscombe explained how the project unravelled. After visiting the nursery in Vietnam, the Vietnamese partners had the difficult job of collecting seeds from tree in the wild before sending them to the UK.
One of the biggest challenges faced by the team at Bedgebury was how little material was available to work with. As populations are so low, only a small number of seeds could be collected and of these, x-rays showed the seed quality was fairly poor with low viability, making it essential that no seed was wasted. With this tall order, the staff at Bedgebury began propagation trials for these seeds to find out which soils, pots, humidity and water regimes best suited these trees.
The seeds germinated late in the year which is unusual for conifers, and with the fear that the seedlings would not survive the winter, they were transferred to Royal Botanic Gardens, Kew, Wakehurst to over winter in their glasshouses under grow lights. When they made it back to Bedgebury, growing them on in the nursery proved relatively straightforward and survival rates were high.
This May the seedlings were finally big enough to be planted out in the pinetum at Bedgebury. Somewhat surprisingly these trees have so far had no problems with the temperatures of England, despite being a little chillier than its native Vietnam. Dan notes that sensors in the Pinetum have recorded temperatures as low as -15°C, however, the cutting raised trees already planted out here have survived unharmed, suggesting the seed raised plants will also survive this winter.
Dan highlighted the importance of sharing best practice for seed storage and propagation of these threatened species. Without the sharing of expertise and plant materials, projects such as this one are unable to get off the ground. The results of the propagation trials will be shared with the Vietnamese partners with the hope that more extensive propagation can begin in
The results of the propagation trials will be shared with the Vietnamese partners with the hope that more extensive propagation can begin in country. Because of the difficult nature of propagating threatened tree species, Dan stressed the importance of botanic gardens like Bedgebury building and maintaining close links with seed banks, making sure these species are protected in case they are lost in their natural environments.
With plans to transport the plants back to Vietnam there is hope for this species. Whether they are planted within the tree’s current range or in the nearby ex situ planting site, they will hopefully, in conjunction with ongoing work to protect its natural habitat, contribute to getting Vietnamese golden cypress ‘out of the woods’ and lower its risk of extinction.
Bedgebury National Pinetum & Forest in the High Weald of Kent is home to the National Conifer Collection, and is recognised as one of the most complete collections of conifers on one site anywhere in the world, containing over 12,000 tree specimens growing across 320 acres including rare, endangered and historically important specimens. The Pinetum contains some 91 vulnerable or critically endangered species and five NCCPG National Collections (yew, juniper, thuja, Lawson cypress and Leyland cypress) as well as some of the oldest and largest examples of conifers in Britain.