Importation of Ash trees is now banned in the UK

The subject of tree health within the UK is now gaining a heightened media profile and increased governmental attention, but is it too late for our beloved woodlands?

The Ash tree ban has captured the nation’s attention and a segment in the BBC’s nationwide Weekend News last night stressed the issue of tree health. Today the ban on importing Ash trees comes into effect; eight months after it was first identified in the UK and 25 days since Defra launched its consultation. So far the press is particularly focused on the invasive fungus (Chalara fraxineae– Dieback disease) that is currently threatening 80 million Ash trees at 23 sites throughout the UK. Ash trees are a prominent species (along with Beech and Oak) within UK Woodlands, contributing between 15-30%, and aged specimens contain a rich community of lichens. A mass Ash tree death as seen in Denmark, where the same disease has already wiped out 90% of their Ash population, will not only impact on the aesthetics of UK Woodlands but hamper the functioning of the ecosystem and potential climate change mitigation plans.

On BBC 1 last night a representative from the Woodland Trust (Austin Brady) said that he believed the government response was lacking speed and efficiency (as are all experts in the press) but also highlighted a key fact.

“Ash dieback is one of many tree parasites that are posing a threat to UK Woodlands”

The issue of tree health has been given more precedence in the last couple of years. The Parliamentary Office for Science and Technology (POST) released a POSTnote in October of last year summarising the current knowledge and actions at the time. Defra’s 2011 Tree Health and Plant Biosecurity Action Plan, is centred on improving governmental response to this issue in four chosen areas; (A) Protection, (B) Practical actions, (C) Public and stakeholder engagement and (D) Research opportunities and evidence priorities (as highlighted in last week’s blog). The progress update published in June, showed that protection measures had been improved (the current ban being an example of such action) but a risk framework for the prioritisation of action has still not been published.

While a media frenzy concerning the threats to Ash trees and the speed of government response is debated; there is a real need for the parties involved to use this ‘limelight’ to improve public perception, action and understanding of the fundamentals pertaining to this topic. The Forestry Commission’s Pest Alert posters and leaflets provide a good source of information aimed at the public so that we can all become actively involved in saving our Woodlands (C. fraxineae; Phytophthora ramorum– Sudden Oak Death).

Tree parasites are a necessary part to the ecosystem as decaying wood provides the some of the most biodiverse communities in forests and woodlands. If a disease strikes a particular tree it attacks the entire species, as well as associated species (both rare and abundant) that range from wild birds, butterflies, lichen, smaller trees and shrub species (Kirby et al., 2010). The age distribution of a tree species is also an important factor; veteran trees provide unique habitats for highly specialised organisms and landscape features but at the same time are much more susceptible to disease (Wilson, 1992; Kirby et al., 2010). The last point is that in any ecosystem it takes decades for surveillance and monitoring to discover a new disease. and successful management of a disease takes even longer. First the ill-health of a species must be recognised, the casual link to a process or parasitic entities must be established, the parasitic species must then be identified before the simultaneous initiation of research and management practices.

Dr Jon Heuch, an independent member of the Forestry Commission’s Biosecurity Programme Board, stated that (in the case of Ash dieback) C. fraxineae was thought to be in the UK several years ago but not the disease agent. It was only after years of research that C. fraxineae was identified as the causal organism of Ash dieback disease. In most cases management consists of spread prevention by increasing import/export measures and the felling and burning of infected trees as exemplified by the 50, 000 infected Ash trees already destroyed. This is not always effective and given the time it takes to get to this stage, it is not surprising that sometimes the damage is already done by the time we notice that anything odd is even happening. That being said the new LWEC Tree Health and Plant Biosecurity Initiative is now under-way and will begin to fill this expertise gap. This is a venture which is especially relevant considering the future increase in invasive species as the climate changes.

In 2013 the BES is likely to produce a volume of Ecological Issues on this topic, to synthesise the current knowledge and actions concerning tree health. If you would like to become involved this please contact us at:


Kirby, K.J., Perry, S.C., Brodie-James, T. (2010) Possible implications of new tree diseases for nature conservation. Quarterly Journal of Forestry. 104: 77-84

Wilson, E. O. (1992) The Diversity of Life. London: Penguin Press