Burning Questioned
On fires and finding reassurance
The coppicing season is drawing to a close now and so too is the necessity for the fires which are one of the highlights of conservation volunteering in the winter months. There is something special about being out in the open air and staring into the flames of a fire made from wood you’ve cut yourself. Some of the volunteers bring potatoes to bake on the fire. Once someone even brought a tin of baked beans to heat up and eat with her lunchtime spud and I still have fond memories of the time some years ago when we roasted chestnuts on the embers of the fire at the end of the day. Even if we’re not using it to cook food, we’re all glad of the warmth from the fire when we take a break for lunch, particularly on chillier days. And if I’m arriving late to a workday, I often use the sight and smell of woodsmoke to locate the others in the woods.
So there are many benefits for us but the main reason we have fires is that coppicing produces a lot of arisings – the brash and smaller branches that are left over after we’ve processed and set aside the long straight lengths for future use as fence posts or hedge binders. In the past woodlanders would have taken some of these arisings away with them to be burnt on the fires they used for cooking and heating their homes, but the rest would have been burnt where they were working. And burning is still by far the easiest way of getting rid of arisings from many of our winter conservation tasks.
Sometimes we create dead hedges out of the cut wood or pile it up and leave it to rot down. But neither of these approaches are feasible or appropriate in places where we’re producing a lot of arisings. Another option used in some places is to bring in a woodchipper and take the chipped material away afterwards but that’s only really practical where there’s easy access to a road. Often there is no realistic alternative to burning the arisings.
My delight in bonfires has lessened somewhat since I went to a talk about ancient trees and learnt about the damage fires can do to the mycorrhizal network of fungi that connect trees and other plants to each other underground and allow them to exchange nutrients. Some organisations now address this concern by building the fire on a specially constructed platform to keep it off the ground, but that’s only an option on sites which are accessible by vehicle and where there is the right kind of vehicle available to transport the platform, neither of which apply on our TCV workdays. We focus instead on picking fire sites as far away from the trees as possible, keeping the fires small and sticking to the same sites to minimise the area of ground that is damaged.
Some local authorities in more built-up areas have now banned bonfires as part of their plans to reduce air pollution, or because of the nuisance they cause to neighbouring properties. But the fires we have in the woods are some distance from the nearest houses and if the residents of those houses have fitted log burners, as huge numbers of people have in recent years, then it’s possible they’re likely to be having even more impact on air quality themselves.
Research in 2021 found that although bonfires produce up to 30 times more smoke than burning logs in a stove, the smoke from wood stoves is actually far more dangerous as it contains up to 12 times as much of the most harmful types of particulates (known as PM2.5) which can cause health problems such as lung cancer and asthma. The rapidly growing popularity of log burners in recent years has led to increasing concerns about their contribution to air pollution. In 2022, the burning wood on log burners and open fires in the home accounted for a nearly a quarter (22%) of all PM2.5 emissions, a greater contribution than road transport at 18%. The Government has now introduced new rules aimed at restricting the amount of smoke log burners are allowed to produce in most urban areas in England but there are no plans to ban them entirely.
Burning wood contributes to carbon emissions too of course, but the contribution from bonfires is far less than that from road transport or industry. And the alternatives to burning might have just as much impact if, for example, if a vehicle is used to bring in a woodchipper and take the chippings away.
It’s the potential for fires to cause long-term damage to the ground they are laid on that worries me the most so I tried to find some evidence about exactly how much impact our small fires are likely to have. Most of research I found related to much larger fires, either unplanned wildfires or the intentional burns used for vegetation management in some places. But then I found a scientific review which looked at the impact of a range of different types of “human-induced” burning and concluded that “pile burning” does have significant impacts on the soil and can result in the loss of seed banks loss and the killing of fungi and fine roots. But importantly “these impacts are localised and, unless the piles occupy large or sensitive areas, [the] effects are considered as being irrelevant at the landscape scale”.
It seems that perhaps I have been worrying unnecessarily, but I’m glad I found that reassurance as now I’ll be able to enjoy our fires again next winter.
To finish….
…a few things I’d like to share:
Trees and Woodland in the British Landscape: The Complete History of Britain’s Trees, Woods and Hedgerows by Oliver Rackham. Rackham was a highly-regarded naturalist who drew on his extensive fieldwork and research to write several books about trees and woodland which are often quoted by other nature writers. This book provides a detailed history of the changing role of woodland in Britain from prehistoric times until the end of the twentieth century and challenges many long-held assumptions about the way in which human action has had an impact on woodland in Britain over time.
Fungi: Web of Life film. I mentioned Merlin Sheldrake’s book Entangled Life when I wrote about fungi a couple of months ago. Now Sheldrake you discover the highlights from the book in a documentary narrated by Bjork which is showing in 3D at the BFI Imax on the South Bank. I haven’t managed to see it yet and the only forthcoming screening is sold out but this review makes it sound like a great experience and I’ve been enjoying watching the trailer.
Treemoot International Storytelling Festival. Over a series of Saturdays from April to November, the Great North Wood will be hosting a Storytelling Festival with a whole range of amazing (and free) events and workshops celebrating trees and woodlands. You can find out more and book tickets here.
That's very reassuring. Thank you.
Yes, I was relieved to find that article. Glad you found it helpful too.