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Report by Fiona Mahon, Countdown Biodiversity Coordinator.
The Cheshire Native Black Poplar LBAP (Local Biodiversity Action Plan) Action Group recently organised a black poplar identification training day at Ness Botanical Gardens, Wirral, held on Saturday 17th May 2003.
About 30 conservation volunteers and wildlife practitioners enjoyed a day of seminars and practical exercises aimed at teaching the art of identifying the rare native black poplar from the more common hybrid variety.
The black poplar (Populus nigra subsp. betulifolia) is considered to be the most endangered native timber tree in Britain. It is thought that there is a national population of 6-7,000 trees with only 300 occurring in the Cheshire region (which comprises Cheshire, Halton, Warrington and Wirral). Approximately 50 percent of the trees in Cheshire are female which is higher than other parts of the country where males dominate. In Cheshire, black poplars are found mainly along the floodplains of the Rivers Gowy and Weaver.
The training day on the 17th May commenced with a talk by Fiona Cooper, the BSBI (Botanical Society of the British Isles) national recorder for black poplars. Fiona gave some historical background to the black poplar including its importance as a source of timber. Its wood was used in furniture, as a fire proofing material and to make clogs and cart bottoms. It was also believed to have medicinal properties.
Fiona also spoke of the black poplar's role in folklore. The tree features in poetry and art. It was thought to symbolise fertility, perhaps due to its fast rate of growth, and the trees were, therefore, often dressed as part of wedding ceremonies.
The decline of black poplars in Britain is thought to be due to many factors, the main one being hybridisation with non-native poplars which were introduced to this country in the mid 1700's. The population of black poplars today is largely made up of old trees growing in isolation, with few opportunities for natural regeneration.
Black poplars have also been felled more recently to make way for road building and development. The black poplar has a natural lean which has caused indiscriminate felling of trees that are considered to be unsafe. Through awareness raising it is hoped that in the future measures such as careful management and selected pollarding of old trees could help to save this rare species.
Fiona went on to talk about her genetic research work on black poplars. She has, so far, tested 170 trees, mainly in Ireland and Britain, and has found many to be identical to each other. The offspring from trees at Willaston, Wirral, were found to be identical to a number of trees. Fiona found no genetic difference between male and female trees.
Through Fiona's research she has found out that the Manchester Poplar, which was thought to be a separate clone of the native black poplar, is in fact identical to trees growing in Shropshire, Staffordshire and Ireland. The only difference is that the poplars in Manchester are planted close together which gives them a slightly different form and appearance.
Since 2001, many of the black poplars around Manchester have been affected with a new disease, a form of bacterial canker causing spring defoliation and the tips of twigs to blacken. It is thought that very humid conditions led to its development. A hot, dry summer could possibly cause its eradication.
As a result of the disease, all street black poplars in Manchester have been felled due to health and safety concerns. Although there is still little known about the disease, if it were to spread across the country it would be catastrophic for the national population. However, as most of the trees are isolated then this may reduce the spread of the disease.
Fiona discussed the options for conserving native black poplars in the future. A national clone bank needs to be created, particularly containing trees of historic importance. We also need to protect trees on existing sites and encourage landowners to plant cuttings from their own mature trees. Further research is needed on particular issues, such as, the effects of climate change, stress and changes in the water table on black poplars.
Fiona finished her informative presentation with several slides of black poplar images which illustrated some of the characteristics of the native trees.
Following a coffee break Hugh McAlister of Ness Gardens led a practical session on identification using samples of black poplar trees that delegates had brought with them. Fiona Cooper was on hand to scrutinise each sample closely and after much deliberation most were divided into natives and hybrids with some surprising results.
As a guide to identification, native black poplars are generally untidy in their appearance with down-sweeping branches and up-sweeping twigs. Their crowns are compact and they lean in silhouette. Their bark is dark with very irregular cracks and fissures, depending on the age of the tree. The leaves are long, diamond-shaped rather than heart-shaped and green with some slight bronzing. There may be hair around the leaves but there should be no glands on the leaves of natives. The male catkins are very red in colour and the female trees produce masses of white fluff.
Following a very tasty lunch provided by the catering staff at Ness Gardens, delegates enjoyed a stroll around the grounds (despite the inclement weather) and Hugh showed us examples of both hybrid and native black poplar trees on site.
Before parting there was an opportunity to look around the visiting craft fair, and Ness's plant shop and gift shop. A very pleasant and interesting day was had by all!
For more information about black
poplars, please contact the Native Black Poplar LBAP Coordinator, Sarah
Bird, at Chester Zoo on 01244 380280 ext 448.
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