The latest menace is Ash Dieback (Chalara) in non-woodland trees. ‘Remember the Dutch elm disease devastation,’ said David. ‘As there are more ash than there were elm trees, this will be 80 times worse.’
The Tree Council held a forum this summer on the impact of the disease. More than 70 delegates explored the latest science and began to develop local action plans.
‘Ash dieback is a new disease previously unknown in Europe caused by a fungus,’ said David. ‘The disease causes leaf loss and crown dieback in affected trees, and it can lead to tree death. The first cases were confirmed in Great Britain early in 2012, on ash plants which had been imported from The Netherlands. The fungus is extremely aggressive with leaf wilt and diamond-shaped lesions appearing on the bark.’
Trees cannot recover from infection. But larger trees can survive infection for a considerable time and some might have genetic resistance and escape death. ‘But the potential impacts of Ash Dieback reach beyond the decline of ash trees,’ said David, ‘threatening the populations of a range of animal and plant species dependent on ash – as well as profoundly altering the habitat of ash-dominated woodlands, especially in the long-term.’
In non-woodland situations the impacts of even quite low levels of ash death – particularly of mature and veteran trees – could also be significant. ‘The relative contribution of the individual trees to landscape and wildlife value is greater than in woodland,’ David explained. ‘We need to accept that our woods, parks, hedgerows and highways will be different in future.’
A Rocha UK supporters can play an important role by monitoring their local ash trees and reporting to the Forestry Commission. For further information visit www.forestry.gov.uk/chalara.