This is the final article in a six-part series about how Perthshire Big Tree Country is helping to save internationally threatened conifers. Felicity Martin discovers how two sites near Aberfeldy are continuing a tradition of planting unusual species, and looks at what the future holds for the iCONic project.
30 August 2014
Looking to the future
The unending story of plant discovery
It is tempting to think that we have learnt all there is to know about the natural world, but that is far from the truth. Our knowledge is still expanding, with the ongoing identification of new species and an increased understanding of how interrelated factors affect the biodiversity of the environment.
One place in Perthshire that demonstrates this continuing journey of discovery is Cluny House Gardens, near Aberfeldy. The most famous tree in the gardens is a magnificent giant redwood that is the widest conifer in Britain, with a girth of 11 m (35 feet). This Californian species was introduced in 1853 by the Perthshire plant collector, John D Matthew, and the Cluny tree probably comes from his original seed collection.
Another conifer in the gardens with a special history is the dawn redwood, which was believed to be an extinct species until it was discovered growing in south-west China in the 1940s. It is unusual in being deciduous, like the larch, with soft, pale green foliage that turns reddish-orange in the autumn before the needles drop leaving the tree bare in winter. Although widely planted in the UK, where it thrives in a wide range of conditions, it is critically endangered in the wild where it is found in very few locations.
Cluny provides a natural home for several new iCONic specimens, including Alerce, Chilean plum yew and three Florida torreya. The wild woodland garden, planted on a steep hillside with a mix of trees, shrubs and flowers, has the atmosphere of a Himalayan woodland paradise.
This environment suits one of the world’s most recently discovered conifers, the Vietmanese yellow cypress, which grows in a humid and precipitous landscape. In 1999 biologists surveying on a karst limestone mountain in northern Vietnam found an unusual conifer with golden yellow cones. Experts failed to identify their samples and eventually it was found to be a new species, belonging to a genus thought to be extinct. The Royal Botanic Garden Edinburgh introduced the species into cultivation in 2002, growing it as cuttings and making a concerted effort to ensure that every single introduced clone was propagated into multiple plants to insure against their loss.
Bobby Masterton, who created Cluny House Gardens from the early 1950s, also planted the nearby Birks of Aberfeldy Tree Collection, which contains a range of exotic specimen trees. Since the deaths of the Mastertons in the 1980s, Cluny has been managed by their daughter, Wendy and husband, John Mattingley, who maintain a holistic, natural approach to its care.
Continuing threats to the world’s conifers
Even as we are discovering new species, fresh threats are appearing for existing ones, including some that are so numerous that it is difficult to believe they could be vulnerable.
One such is the Lawson’s cypress, probably the most common garden conifer grown in Britain. Its great genetic plasticity has enabled hundreds of cultivars of all shapes, sizes and colours to be derived from it. When the Royal Botanic Garden Edinburgh’s International Conifer Conservation Programme began 23 years ago there was no concern for this species in the wild.
However, it is now highly threatened in its wild state in northern California by a pathogen, Phytophthora lateralis, that spreads along watercourses and enters the tree through the root system. The disease, which can be spread when soil is transferred between sites, is now devastating native forests. The iCONic project had intended to work with this species, but two years ago the same pathogen was also discovered in the UK, posing a risk to this ex-situ conservation strategy.
Impact of climate change
A couple of miles up Strath Tay from Cluny House Gardens is the small village of Weem, above which hang the wooded crags of Weem Forest. This ancient place has been occupied by humans for millennia, from the prehistoric people who carved cup and ring marks into the rocks, to St Cuthbert, a 6th century Christian missionary, and St David, a 15th century laird, both of whom retreated to its caves as hermits.
Castle Menzies lies at the foot of the slope and it is here that the father of the plant hunter Archibald Menzies worked as a gardener. The family association led to many introduced specimens of conifers being planted through the deciduous woodland. Since then the wood, no longer in private ownership, has become part of Tay Forest Park.
The iCONic project has been working with Forestry Commission Scotland to revive the tradition of introducing unusual conifers by planting two threatened species where there are gaps in the canopy. Groves of both Serbian spruce and Spanish fir have been established, using a naturalistic style of planting.
Spanish fir has two subspecies that grow in southern Spain and northern Morocco. Both populations are at risk of fire, grazing and climate change. Pests and diseases cause greater damage during drought years when the forests are more stressed. Over the last two decades a decrease in rainfall has been observed in these regions, along with a trend towards warmer temperatures. As that has happened, there has been increased mortality of trees at lower altitudes. Many species worldwide, including in the UK, could be facing similar problems.
The future of the iCONic project
Conifers are a vitally important group of plants that support a wealth of associated biodiversity. They are essential components of the ecosystems in their native range, and the vast conifer forests of the northern hemisphere act as huge carbon sinks. Throughout history, they have provided timber for construction and fuel, and they also contain compounds that may have medicinal value in the future.
The partners in the iCONic project – the Royal Botanic Garden Edinburgh and its International Conifer Conservation Programme, and, in Perthshire, Forestry Commission Scotland and the Perth & Kinross Countryside Trust – believe they can help save threatened conifers. Syd House, Forestry Commission Scotland’s Conservator for Perth & Argyll, sees hope for the future.
“By 2022 we hope to have planted over 10,000 individual conifers across Perthshire through the iCONic project, representing at least 20 species. In fifty years time, when they are well grown trees, these new collections could be drawn on to help restore depleted forests around the world.
“Of course, many more species may be threatened by then if global warming and economic development continue as projected. That means there may be even more work for us to do in future.”
One of the ongoing challenges for iCONic is to find the funding needed to plant trees and care for them. The project welcomes cash donations of any level and offers a range of imaginative and meaningful sponsorship opportunities for corporate and private supporters. It also provides volunteering experiences for individuals and organisations, ranging from horticultural work to tree planting and growth monitoring. For more information, contact the project officer, Tom Christian.
Anyone interested in the progress of the project is encouraged to become a Friend of iCONic and to help to spread the word. Registration is free, and all you need do to be kept up to date with news and events is sign up for the quarterly e-newsletter. News, activities and photos are also shared regularly on Facebook and Twitter.
Next month we will post a compilation of this and the previous five articles in a free to download pdf e-book.
Find out more from the iCONic project website.