Elm Trees (Ulmus spp.)

There are three British Elms plus a number of hybrids and cultivated forms, all of which can grow into large trees: English Elm (Ulmus procera), Wych Elm (Ulmus glabra), and Smooth-leaved Elm (Ulmus carpinifolia).

The English Elm is thought be native to Britain and was once a common species of wet woods, hedgerows and drain banks. The English Elm grows to about 30m, and forms suckers which produce new trees. The leaves of the English Elm vary in size and shape; they are dark green and rough above with pale down beneath. The bark is dark brown and cracked into small rectangular plates. Many localised forms occur in different parts of Britain.

The Wych Elm is native to Britain. It is a large tree, growing to over 40m and is often seen in parks as a specimen tree. The flowers open in early March. The leaves are rough on the upper surface and softly hairy beneath with very short stems. The bark is smooth and grey, with cracks and furrows on mature trees.

Smooth-leaved Elm is native to Europe (possibly including Britain). It grows to about 30m with upright branches forming a dome shaped crown. Leaves are always bright shiny green above with tufts of down beneath. The bark is greyish brown with long ridges and furrows.

There are several species that are dependent on Elm trees. The Elm is the only larval food plant of the White-letter Hairstreak butterfly (Strymonidia w-album); therefore the survival of this species is directly linked with that of the tree. The bark of Elm trees provides a distinctive surface on which lichens can grow. The Orange-fruited Elm Lichen, an UK BAP priority species, is found only on Elms. Elms are also important for many bird species.

Current Status

English Elm was once widespread in fields, hedges, parks and streets, but was devastated by the Dutch Elm disease fungus (Ophiostoma novo-ulmi) and is now rarely planted. The Wych Elm is also suffering from Dutch Elm disease and associated lack of planting across the UK. It is estimated that Dutch Elm disease has killed over 80% of the UK Elm population.

The most common Elm species in Hull, prior to the Dutch Elm disease outbreak in the 1970s were Wych Elm, English Elm and Wheatley Elm (a cultivated form of the Smooth-leaved Elm). English Elm had a high population in the area but being perhaps most susceptible to disease due to its thick bark, was decimated in the 1970s and 1980s. Although the parent trees died, the rootstock often escaped infection and sent up sucker growth. This is not resistant to the disease but, assuming that it does not become infected, will eventually grow to maturity. Populations survive at Sutton Golf Course and Springhead Golf Course. The Wych Elm is not as frequent in Hull as the English Elm but a large specimen tree grows in Kingston Gardens.

The most abundant Elm in Hull was the Wheatley Elm. The tree was planted along highway verges and Hull used to have thousands of these along major roads, and avenues throughout the city. The City Council Urban Forestry Department holds records of former Elm avenues. Dutch Elm disease killed many of the roadside and park Elms. Very few remain and the species is now uncommon locally.

Current Factors Affecting Elm Trees

• Dutch Elm disease has caused the death of many trees. There is a low base population and lack of uninfected local provenance stocks.
  
  
• The incidence of Dutch Elm disease is declining as host trees become rarer but there is always the possibility of the disease returning.
  
  
• Elms do not readily regenerate from seeds and only the English Elm has the ability to regenerate by vegetative means. The survival of the species depends on planting.
  
  
• Illicit grazing prevents natural regeneration.
  
  
• Mature trees are often subject to vandalism and saplings are often destroyed.
  
  
• Inappropriate hedgerow management may lead to the loss of naturally regenerating Elms.

Current Action 

Legal Status

Timber import and internal sanitation measures exist under the Plant Health Act (1967). The problem of Dutch Elm disease was so severe in the late twentieth century that the Restriction on Movement of Elms Order (1984) was passed to prevent movement of the species. The Order was amended in (1988) and Humberside was removed from the list of areas into and within which the movement of Elm is restricted. This Order was abolished in 1996.

Management, Research and Guidance

The Forestry Commission carries out research into disease mechanisms and control measures. There is currently no research or management relating to Elms carried out within Hull.

Action Plan Aims

1. To determine the number and distribution of remaining Elms in Hull.
   
2. To monitor the distribution of Elm trees in Hull.
   
3. To monitor Elm sucker recovery growth.
   
4. To collect and propagate Elm material from local trees.
   
5. To manage hedgerows and woodland to benefit Elm trees.
   
6. To promote planting Elm saplings produced from local trees.
   
7. To provide advice on Elm management and Dutch Elm disease.

What We Are Going to Do

What We Can All Do

• Let the Biodiversity Partnership know if you have Elm trees in your garden.
  
• For any advice on Elms contact the City Council's Urban Forestry Section.
   

Links With Other Action Plans

Management of Trees, Scrub and Hedgerows will involve action for Elm trees. Elms may provide an important habitat on which Lichens can grow. The loss of Elm trees has reduced the availability of nest holes for Tree Sparrows and Spotted Flycatchers.

References

Phillips, R. (1978) Trees in Britain, Europe and North America. Pan Books Ltd, London.