Last summer, five UK dendrologists embarked on a three-week expedition to the Pacific north-west coast of the USA, travelling 4000 miles, securing seed for tree species’ futures.

Representatives from GTC partners the Forestry Commission’s Bedgebury National Pinetum and Oxford University Botanic Gardens Harcourt Arboretum, along with the Forestry Commission’s Westonbirt National Arboretum, visited three states (Washington State, Oregon and California) last summer in search of seeds from highly threatened trees to incorporate into ex situ collections both in the US and back in the UK.

The team saw forest ravaged by wildfires, the effects of which had been exacerbated by extensive drought. They drove through an area of 300,000 hectares of devastated forest that has yet to regenerate. Climate change is likely to intensify this threat and increase the risk of extinction of all the species in the region. Trees like the White Bark Pine (Pinus albicaulis EN) are threatened not only by wildfires but also by pests and diseases. Increases in temperature provide conditions for increased pest outbreaks. Models suggest that in 70 years’ time, with continued warming, the White Bark Pine could be reduced to just 3% of its current distribution.

A tall task

With this in mind, there was a lot of work to be done! Four thousand miles were travelled across the West Coast to collect seeds from nearly 90 different trees and shrubs including conifers, oaks, dogwoods, maples and walnuts. Various threatened tree seeds were collected including Sequoia sempervirens (EN), Pinus albicaulis (EN) and Juglans californica (VU), some of which involved some impressive climbing skills to reach seeds highest in the canopy.

The night time offered no respite from the intense work regime. Seeds needed to be removed from cones, cleaned, dried and securely stored following collection to ensure they arrived in the UK in top condition, and free from pests and disease. This was done every night in various campsites and hotel rooms along the way.

On their journey, the team encountered some of the world’s threatened trees, as well as the tallest (coast redwoods) and the oldest (bristlecone pines), all in their natural environments, which provided invaluable insight into how to grow and conserve them. Meticulous records were taken of the trees’ habitat including exact locations, aspect, soil type and condition of the habitat which may be useful in the future for restoration programmes.

Securing species’ futures

As the aftermath of recent fires demonstrated at the outset of the journey, seed collecting trips such as these are vital to protect the world’s most threatened trees. As well as adding to UK living collections, collections were made for the Millennium Seed Bank. These seed collections preserve seeds over the long-term; a sort of ‘insurance’ policy which can be used to restore populations in the future. Safeguarding these species in ex situ collections may prove important in the future with increasing threats to the wild populations from climate change, deforestation and drought.

Although not all the seeds collected on this trip came from threatened species, circumstances can change quickly and with added climate pressures, it is sensible to have back-ups in the form of ex situ collections. The seeds collected on this trip are already back in the UK where they are now starting to germinate, providing a lifeline for some of the world’s most threatened tree species.

The trip has also contributed to a new outdoor photography trail at Bedgebury National Pinetum and Forest from 24 March until September 2016. The trail highlights their internationally important contribution to conserving rare and endangered conifers whilst showcasing the importance of the US seed collection trip through a series of large scale photographs. To find out more about this exhibition, please see Bedgebury’s website or Facebook page.

It is hoped that the team can build on the success of this expedition and plan further fieldwork with the US Forest Service.

Acknowledgements:

The expedition team want to express their thanks to the US Forestry Service Geneticist, Andrew Bower and Matt Lobdell, Curator at The Morton Arboretum, who assisted the team for the first two weeks of their trip, providing some excellent on-the-ground knowledge to speed up the collection process. In Southern California, the team worked with Evan Meyer, seed conservation program manager at Rancho Santa Ana Botanic Garden.

The Forestry Commission’s Bedgebury National Pinetum and Forest and Oxford University Botanic Gardens Harcourt Arboretum are Global Trees Campaign project partners.