Beyond ash dieback

Towards the end of last week the phone started ringing. I’d been expecting this for some time. The news had just come through that ash dieback had been discovered in Nottinghamshire, not far down the road from my office. This is something I had anticipated several years ago, though I make no claim of special prophetic gifts. It was obvious that it would. The disease has spread systematically from the east of Europe, sweeping unimpeded right the way to Holland (see the Forestry Commission website for an excellent summary of the disease and its background). It was only a matter of time before it made it to the UK, and once established there was no keeping it from Nottinghamshire. This despite the British government convening a meeting of COBRA, the national emergencies committee, in an effort to be seen to be Doing Something. They might as well have objected to clouds.

The reason I was suddenly being called was the estimate by Nottinghamshire County Council that 40,000 trees might need to be removed in the next five years. As ever, journalists settle on the story first then try to find some talking heads to fill in piece with some choice quotes. In every phone conversation it quickly became clear that they wanted me to say how terrible this was so that they could set up a conflict with the Council’s plan. “Academic says save our trees!” All of them finished the conversation disappointed with my failure to play the game.

This culminated in an appearance on Notts TV alongside a friend from Notts Wildlife Trust in which they were hopeful that one of us would bite. The trouble is, we both agreed. The actual numbers are an estimate, and not worth fighting over, but the basic principle remains. Trees are going to have to be cut down.

Why am I so willing to accept this drastic intervention? The simple truth is that most of these trees are going to die anyway; the Danish experience suggests as many as 90% will eventually succumb to the disease. Most of these have been planted, often from commercial (and frequently non-native) stock. Ash is favoured as a screening tree along roadsides and around developments because it grows tall and fast. Not all trees are equal, and a young planted ash tree ranks pretty low in terms of its conservation value, relative to say an ancient yew or a small-leaved lime. Trees that are sick and dying are not merely an eyesore, they’re a risk, especially along roadsides, paths and bridleways. Land owners would be legally liable if they fell on someone. The Council is being perfectly sensible and their press release was simply preparing people for the worst.

While some have capitalised on the flurry of interest by launching projects to characterise the ash genome or develop resistant trees, these aren’t going to make a difference in even the medium term. I can’t blame people for using a news story to get some research funding, but these are not solutions to the problem. The trees are going to go, and the landscape of the UK will be changed for at least a generation.

The issue that really matters is what we choose to do next. Where ash trees succumb on private land or in closed woodlands, they should be left alone to die and fall. This will create a large resource of dead wood which will benefit a wide range of species, especially insects and the birds which feed on them. Where large trees fall, they will create gaps in forests that other species will benefit from. There are many woods (particularly here in Nottinghamshire) that only exist because ash colonised abandoned fields following WW2 when marginal land was pressed into production. These are now 70 years old and have plentiful seedlings beneath them — oak, field maple, hazel, wych elm — all of which will grow to fill the place of the missing ash. Our woodlands will change, but nature is dynamic and ceaseless change is a rule. Their composition was never natural in the first place (if natural is taken to mean wild and unaffected by human influence), so it’s hard to make a case for their preservation or restoration. Let’s see what happens. It’ll be interesting.

In urban areas, people appreciate the presence of trees, and will miss the ash when they are gone. The question we should be asking is: what will we plant in their place? Instead of introduced species (e.g. London plane, which isn’t from London at all) or those which offer little to wildlife (e.g. whitebeam), why not take a longer-term approach and plant a variety of native species that will bring more wildlife into our towns along with variety and interest? What would you like your grandchildren to be walking under in a century’s time — another monocultural row of ash, or a lane of oak, beech, hornbeam, lime and black poplar? The death of our ash trees will leave a gap in our landscape. But any gap is also an opportunity.

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