Saving a Rare Species – The Plight of the Elm

East Dartmoor Woods and Heaths National Nature Reserve is just one of over 200 NNRs across England, and Natural England designate these areas to “protect some of our most important habitats”. These conservation areas are widely varied but, here in the woods of East Dartmoor, a team of volunteers is helping to conserve a tree that, over recent decades has become scarce and, while being worthy of protection itself, it also holds the key to the survival of a rare butterfly.

East Dartmoor Woods and Heaths - view of Hisley Woods from Trendlebere Down

The wych elm is one of the species that is at risk from Dutch elm disease, a fungal pathogen spread by elm bark beetles. The disease was researched by Dutch scientists who discovered how the beetles, feeding under the bark of the elm, would introduce the fungus which interferes with the water conducting systems in the tree. Visible signs of the disease are the yellowing of leaves which then turn black and drop from the tree, then whole branches will die back before the crown is affected and the tree can die.During the 1970s and 1980s elm trees across the country were dying and being felled in an attempt to limit the spread of the disease. The majority of the larger specimens were lost. Today the general opinion is that wych elm is less favoured by the elm beetle and therefore is, in some respect, more resistant than the English elm. Wych elm favours sites with high humidity and at Rudge Wood and the Woodland Trust’s Hisley Wood in the River Bovey valley, the conditions are good. A number of elms still stand in these woods and, though Dutch elm disease is present, they are surviving. This may be good news for the declining population of white letter hairstreak butterflies that feed almost exclusively on elms.

To be continued ….Information on elm trees and Dutch elm diseaseWhite letter hairstreak informationby Matt Parkins