On 6 December, the Government set out a new strategy to tackle ash dieback. According to government figures, the number of sites infected by Chalara fraxinea, the deadly fungus that causes ash dieback, has more than doubled to 291 in a month.So, what is ash dieback? The Forestry Commission has described ash dieback or Chalara dieback of ash as a “serious disease of ash trees caused by a fungus called Chalara fraxinea. The disease causes leaf loss and crown dieback in affected trees, and usually leads to tree deaths”.
But why are we so concerned about ash dieback? The spread of the fungus is important as according to the most recent Census of the Woodlands and Trees there are an estimated 80 million ash trees in the UK, which is a third of our entire tree population. Ash is a key feature in many habitats, so the loss of ash would result in significant changes to the landscape. This impact would not just be the loss of ash, but also the plants and animals that the trees form key habitats for.
As Ian Wright, plant health specialist at the National Trust said: “If this devastating disease took hold it would radically change some of our most special landscapes and places forever. These ash trees are also incredibly important for the rich flora and fauna only found on such ancient trees, which includes rare lichens, mosses and wood boring insects.”
The decrease in the numbers of ash trees is going to become increasingly important. It is thought that as the climate changes, oak and beech woods are likely to become more dependent on ash in the future. This is because ash regenerates copiously and does not appear to suffer serious bark stripping by grey squirrels to the same extent as many other broadleaved species native to Great Britain.
The National Trust has raised some concerns about the Government’s measures. Dr Simon Pryor, the Trust’s Director of the Natural Environment criticised “The limited actions and weak commitments” as “far too little, too late.”
As there is limited knowledge surrounding the disease, the Government’s proposal of a workshop on research priorities is welcome. However, the Trust is concerned that the workshop is “entirely focused on breeding resistance rather than on techniques that could reduce the rate of spread”.
Why is this important to the Trust? The National Trust looks after 25,000 hectares (61,776 acres) of woodland and forest of which ash is integral.
To date the Trust has had five confirmed cases of ash dieback on its land, four at newly planted sites and one in more mature trees, with this case being in Norfolk. The first case of ash dieback was found on land in the Borrowdale area of Cumbria and nearly 1,000 newly planted ash tree saplings were destroyed. This means that the Trust can try and safeguard nearby veteran ash pollards, some of which are over 400 years old.
The National Trust has worked closely with the Forestry Commission to identify these sites.
The National Trust believes that Government should significantly increase its commitments before the March publication of the updated plans. It would like to see commitment to three critical actions:
- Completing the task of tracing and destroying all infected ash trees planted across the country in the last five years
- Leading a more intensive survey of the core infected area so we know more about the extent of these infections, and how it is spreading
- Commissioning – and funding in full – a range of research into this disease, including into ways of reducing spore spread and increasing the resistance of existing trees.