Chalara ash dieback – what next?

It’s been a while since my last blog on this subject but the question of ash dieback, and tree pests and diseases in general, has never been far from my mind. The level of public concern and media interest in these issues has been enormous and ongoing.

The Government’s promised Emergency Summit on ash disease has been and gone, and their Task Force of experts continues to consider the issues, but nothing has yet emerged. We still have little real idea of what next steps the Government will support until their full Action Plan is published in the next week or so.

No less than two Cabinet Office Briefing Room (COBRa) meetings have been held, and we have some hope for optimism that the views of conservation organisations have helped shape the response so far. We are reassured by Defra’s statement that: “Mature trees will not currently be removed, as they are valuable to wildlife, take longer to die and can help us learn more about genetic strains that might be resistant to the disease”, and we will be pressing them to stick with this position.

The Government response must be soundly based on actions that reflect evidence and experience, and must be credible in terms of really helping the situation. It would be unfortunate if the Government seeks to show its concern by choosing high profile but potentially harmful and expensive activity which delivers little in terms of reducing the spread or impact of the disease.

At the Trust, we are actively reviewing a wide range of our own activities to identify how best we can respond, based on what we know right now. We quickly developed our own 3-Point Plan to address some of the more pressing questions:

  • We are working with others to bring the public and leading scientists together to improve how we identify and monitor tree pests and disease in the UK.
  • We are starting a programme of investing in UK tree nurseries to guarantee that all the planting stock we use in the future will be 100% from UK collected seed, raised and grown on in the UK and free from the risk of importing tree disease.
  • We will bring together leading experts from the UK, Europe and the wider world to share knowledge and learning about the impacts of ash disease and the growing list of wider tree health threats.

We have also embarked on a more considered response to developing a better understanding of the major impacts of ash dieback on conservation and biodiversity in the medium and longer term – this will take some time. We recognise that we will need to engage in wider conversations to pool ideas, knowledge and learning with a range of other bodies and expert individuals. You can read more about our initial Conservation Response here. The impacts on ash will be much more complex than the media headlines suggest, this goes well beyond the simple percentages of what will be lost or estimates of how many million trees are at risk. Some landscapes and habitats will be much harder hit than others, and we need to start thinking about how we respond to that now.

We have stopped planting ash and will continue with this approach until the situation is clearer. Not least because we need to understand the scope for disease resistance in our existing UK ashwoods. However, we are not stopping tree planting altogether – rather, we are substituting other UK native species for the ash and have confirmed that all of the other planting stock we are using this season are UK sourced and UK grown. We have revised our position on the use of local tree provenance to reflect a changing situation and updated our stance on the wider threats from pests and disease.

It is important to keep planting native trees. We need areas of new woodland planting and woodland expansion that can buffer, extend and link our surviving ancient woods and which will contribute to the bigger and better habitat networks that will help make our countryside more resilient in the face of the growing threats from climate change, and pests and diseases.

The full extent of the disease outbreak is still not known, as survey work and tracing infected saplings continues. The Forestry Commission website remains the key source of regularly updated information and provides the definitive source of advice and guidance. Our own response to ash disease and the wider issues around other threats to our native woods continues to develop. You can find more on our website at

Austin Brady, Head of Conservation

About Austin Brady

Director of Conservation (UK) at the Woodland Trust
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10 Responses to Chalara ash dieback – what next?

  1. Pingback: Could the government’s planting target be a springboard for more ambition? | Woodland Matters

  2. petrel41 says:

    Congratulations, Woodland Trust!

    I have nominated your blog for the Blog of the Year 2012 Award.

    The rules of the award are at

    Well deserved! Enjoy 🙂

  3. Peter Bungay says:

    Following the confirmation of the presence in the UK of the ash die-back disease caused by Chalara fraxinea, the Woodland Trust’s 3-point plan to tackle tree disease in the UK is a sensible response that recommends investment in monitoring trees and woods, reducing risk of importation of disease and sharing international knowledge of ash disease. However, as the plan partly addresses tree disease in general, I wonder if it should specifically address ways of minimising the impact of ash die-back disease. An important area of attention may be to plan for restoration of the ash population should the spread of the disease, as is feared, cause most of our ash trees to die off. The entry on the DEFRA website ‘Action on Ash Tree Disease Chalara’ []
    points out a short term action to look for trees that show signs of resistance to Chalara and so may help identify resistant strains. Presumably, resistant individuals could be targeted as sources for propagation. If resistant individuals can be identified during the time the disease develops across the UK (e.g. in younger trees in areas of known infection), we would be in a better position to accelerate the characterization (e.g. genotype) and propagation of resistant strains, should they exist.

    Whilst concentrating on ‘growing our own’ to minimise risk of importing new disease, I am not clear of its value in the case of ash die-back due to Chalara infection, largely because the disease is already here and has been able to have such an impact in other European countries. As you point out, learning from international specialists particularly those that have been involved in minimising impacts of Chalara across Europe could be of great value, particularly if evidence of resistance has been found already. Perhaps the UK-sourcing and growing of ash trees has most value if it contains as rich a mix of specimens as possible to increase the probability of resistance occurring in a new population.

  4. Veronica Sims says:

    While I am in agreement with the comments above I am at a loss to understand why my brother-in law’s gift of a renovated wood (Mancombe Holt), in his will was refused by the Woodland Trust two years ago. This woodland was near Woodland Trust land (in fact bordered on to it). The arrangement had been agreed with the Trust by my brother in law several years before but when he died the Trust declined to take possession of the land. John and many loyal volunteers, over a number of years, did just what you are asking people to do: they planted native woodland trees.

    • Austin Brady says:

      Thanks for your supportive comments about our work. I have passed your question about Mancombe Holt on to my colleagues in our Land & Property Team and they will get back to you.

  5. Mark Fisher says:

    You are right that it is not an issue of simple percentages, although the speculative changes listed in the Conservation Response repeat that error by smacking of orthodox generality. I visit a limestone pavement where grazing was fenced out in 1974. It has undergone a remarkable transformation, aided only by the distribution systems of wild nature, the reclaiming of species mediated through the natural force of wind, the assistance of birds and mammals, and the seeds in their droppings. That this is a developing, functioning ecosystem is readily apparent through the contrast with the depauperate state of the grazed pavements surrounding it and the obvious difference in vitality. The regenerating woodland of ash is just past the shrub stage and into low canopy. These trees may never grow fully due to the thinness of the returning soil and exposure to the wind of the upland climate, but the shadier areas beneath their canopies have a lushness of ground layer vegetation and one can only speculate on what invertebrate life exists in the accumulating decomposition. Butterflies revel in this reforming woodland and there is the sound of birds, missing from the grazed areas.

    Amongst the major differences on this pavement is that the wildflowers are growing on it’s surface rather than in the clints and grykes. This has happened because of the build up of humus and soil-making resulting initially from ash leaf fall, but which then proceeds on the herbaceous cycle of plants combined with the leaf fall. The mix of plants at present cuts across many of the common plant strategies – CSR – and so it is neither all shade (or obligate shade) or all open ground species. It is a botanical garden that could act now as the source of species for the ecological restoration of all the surrounding pavements, but only if grazing was also removed.

    It is difficult to say what would be the immediate changes in vegetation on this pavement when ash die back hits it, considering that there is already some vegetative foothold on the surface in the existing soil/humus. Would there be a process of loss of this surface soil with a loss of tree cover? In the absence of extractive pressures (the sheep) – which of course is why all this started happening anyway – then maybe not in the short/medium term, but the fear is that the soil will be eroded away by water, as happened when the soil was originally lost from these pavements.

    The dead ash trees will of course provide their own increase in habitat for saproxylic species, and those that use tree holes. The lower canopy cover will mean a loss of micro-climate. It will also lead to a reduction in butterflies and birds. Sycamore will become the main tree, if the seed rain continues from nearby grazed pavement. Whether ash influenced the amount of opportunist non-native sycamore seeding in, I don’t know. Being first on the scene and growing maybe the only factor in occupation between those two trees.

    I suppose some may argue that the halt to ash growth comes at the right time to stabilise the extraordinary floristic variety on this pavement, that could change if the trajectory to eventually greater canopy cover continued. This is the pretty banal argument of those who wish to manage everything. My argument would be that the nature of this particular pavement deserves a better appreciation than that banal and oft-trotted out criticism of non-intervention, of creating “dense” shade. Firstly, ash probably has one of the shortest seasons for clothing with leaf. The differential in terms of its shade impact, when compared to sycamore or beech is immense. There will always be a greater variety of light intensity within ash wood, and which favours not only ground flora but also a more extensive and varied shrub layer. Secondly, there are large areas of this pavement that are not jointed, and which will resist for much longer the growth of trees on the surface compared to in the joints. This also gives variety and more light from the open edges. I don’t think the blackthorn and elder that has returned would make a tree; nor will bird cherry or guelder rose that has also come back. The hawthorn also will not make much of a tree there (exposure). You can see the odd quite/relatively large sycamore on nearby grazed pavements. They are non-native, being mountain trees in continental Europe. They produce a much greater shade that ash and would have a significant affect on the ground layer

    It is thus ash that has made this pavement what it is now, and would continue to develop its interest in ways that we just will not see now. If the seeding in of sycamore takes the place of ash, then all the floristic variety is in danger.

    • Austin Brady says:

      Thanks for your thoughtful and thought provoking comments. You are right, that our initial Conservation Response takes a fairly general approach in the first instance. We felt this was necessary in the spirit of prompting a conversation. With something as big as ash dieback and the other long list of pest and disease threats to UK woods, we need to work together and share knowledge and understanding. We will use these conversations to build a more complete picture of the impacts and possible responses to ash disease and will be refining our conservation response over time. So, thanks for your contribution.

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