Westonbirt's World Famous Maples Must Adapt To Climate Change

 

Ref: 10945 – 11 September 2008

FORESTRY COMMISSION PRESS RELEASE
WESTONBIRT  THE NATIONAL ARBORETUM

Westonbirt’s World-Famous Maples Must Adapt to Climate Change

At the PlantNetwork Conference ‘Climate Change and Planting for the Future’ today (11 September), Dr Richard Jinks of Forest Research – the Forestry Commission’s Research Agency  outlines how the Commission is embarking on a full-scale plan to ensure that the world-famous collection of Japanese maples at Westonbirt, The National Arboretum not only weathers climate changes but also thrives in the future.

An evaluation of these and other trees in the collection is assessing their drought tolerance and the best way of helping them adapt to change – through succession planting and good horticultural practices to enhance soil moisture levels in dry summers. There are over 300 types of maples (acers) in the National Japanese Acer Collection at Westonbirt and each autumn they put on a blazing show of colour, admired by many thousands of visitors from all over the world.

Many acers thrive on a constant supply of moisture, and this research emphasises how they could be susceptible to extended periods of drought.
Dr Richard Jinks of Forest Research, said: “These acers are not only stunning trees but also form an important national collection. It is vital that we take stock now and monitor them closely  putting plans in place to safeguard their future. We need to propagate and plant new collections now, not only for 50 years time but for far into the future.”

John Weir, Director of Westonbirt Arboretum, said: “Thousands of people come to Westonbirt each year to stand among and admire these beautiful trees. They are a national treasure and we are doing everything we possibly can to ensure they remain so for generations to come.”

The PlantNetwork Conference is being held at the Royal Agricultural College, Cirencester from 10-12 September. It has over 100 delegates from botanic and historic gardens, Government departments, scientific institutions and universities. This timely conference focuses on planning for an unpredictable future in the face of climate change. Visit www.plantnetwork.org for further information.

- ENDS 

For further information, please contact Gail McKenzie, Communications Officer, Westonbirt  The National Arboretum, on 01666 881 207, or 07919 593131.    email: gail.mckenzie@forestry.gsi.gov.uk

NOTES TO EDITORS
1. Image of Westonbirt acers in autumn attached. Please credit: Westonbirt Arboretum.

2. Westonbirt - The National Arboretum, is managed by the Forestry Commission and renowned worldwide for its tree and shrub collection. It contains nearly 16,000 specimens, including almost half of the woody plants known to grow in the world's temperate climate zone. It covers 600 acres of beautifully landscaped grounds. Its importance is recognised by English Heritage's Register of Parks and Gardens of Special Historical Interest as a Grade 1 registered Landscape. Visitor numbers are 350,000 a year, with a membership of over 22,000.

3. Westonbirt is home to the National Japanese Maple (Acer) Collection, with over 300 different types in the collection.  The Forestry Commission opened Westonbirt Arboretum to the public in 1961, and in 1966 a new Acer Glade was established, alongside the original one planted by Robert and George Holford in 1875. Today, Westonbirt is in the process of creating the world’s best collection of maples.

4. The Forestry Commission is the government department responsible in England for protecting, expanding and promoting the sustainable management of woods and forests and increasing their value to society and the environment. Forestry makes a real contribution to sustainable development, providing social and environmental benefits arising from planting and managing attractive, as well as productive, woodlands. Further information can be found at www.forestry.gov.uk

5. Forest Research is the Forestry Commission’s Research Agency. It is Britain's principal organisation for forestry and tree-related research - providing research, development, surveys and related services to the forest industry and authoritative advice in support of the UK government's forestry policies.

6. PlantNetwork is the national network of botanic and heritage gardens and arboreta and other documented plant collections. It promotes botanical collections in Britain and Ireland as a national resource for research, conservation and education. It facilitates networking and training among holders of plant collections through a programme of conferences and workshops, and a regular newsletter.   www.plantnetwork.org

Westonbirt Arboretum: The National Japanese Maple Collection Case Study

The Forestry Commission is now considering how climate change may affect its principal tree collections – the National Arboreta – at Westonbirt in Gloucestershire and Bedgebury in Kent. As well as considering how they may be affected they are also planning how to address the threats, particularly the projected increase in the frequency and severity of summer droughts.

Westonbirt Arboretum is a Grade I registered landscape established by Robert Holford in the 1850s.  It covers an area of 250 hectares and contains 16,000 trees of 927 species. It is probably best known for its autumn colour display, dominated by the collection of Japanese maples.

At Westonbirt, the first phase of the work has been to screen the collection, focussing on the signature maple species, testing their ability to withstand drought – both extent and duration. Dr Richard Jinks of Forest Research, the Forestry Commission’s Research Agency has undertaken the research by reference to natural distributions and horticultural records and his initial conclusions are mixed. He said: “Although it appears that the majority of the collection is relatively tolerant of summer drought, one group of species – the Japanese maples – are, as a rule, less tolerant. This intolerance to drought is compounded by their location in the arboretum – on the thinner, less moisture retentive soils that will be most susceptible to the effects of declining summer rainfall. If we do not act, I have real concerns for their future.”

However, all is not lost. Forestry Commission staff have put their heads together and thought through some actions that will help to preserve the collection – a process that they feel is worthwhile and achievable:
 The existing collection will be retained with good soil management to conserve water supplies, reduce soil compaction and address risks from pest and disease outbreaks;
 A reactive monitoring programme to identify the most susceptible species/plants/varieties will be ready to be activated during the next extended summer drought;
 The collection will be propagated using on-site facilities;
 A new location will be sort to duplicate the collection on deeper, more moisture retentive soils within the arboretum;
 Reinstatement of the irrigation ponds, originally built by the Holfords, will be considered to provide a sustainable irrigation system for the future;
 The accessions policy of the arboretum will look to re-balance the collection to more drought tolerant species and cultivars;
 Dispersal of propagated material to other FC tree collections and arboreta in more favourable climates of Great Britain will provide further insurance for the collection’s survival as a last resort – albeit on different sites.

John Weir, Director of the National Arboreta is upbeat: “It’s clearly devastating to hear that many of our Japanese maples, the trees that many of the public associate with us because of their magnificent autumn colours, are likely to suffer over the coming decades as a result of climate change. But what’s more important is that there is something practical that we can do about it; as custodians of this important collection we can use the natural environment to ensure that the autumn colour display at Westonbirt continues to thrill future generations, rather than watching it decline as the inevitable effects of climate change start to bite.”

The approach being adopted at Westonbirt is one of ‘no-regrets’ – maintaining and protecting what we already have while putting in measures that will ensure the survival of the collection. Mark Broadmeadow, FC England’s Climate Change programme Manager says ‘this is a great example of how we should be addressing climate change: assess the risks; consider a range of climate change impacts; evaluate the options, and; most importantly – act, without harming what we already have’.