A plea from the trees – how you can help

Do you have a walking holiday planned this year? If so, whether it is here in the UK or overseas be sure to pack your socks, waterproof, poles….and give your boots a good wash before you go. Wash? Yes, that is right. While a wipe over with a cloth and dab of Nikwax might protect your boots from wear and tear, it will unfortunately do little to safeguard the landscape you are looking forward to exploring.

Sadly, British trees are suffering. Just like people, trees are vulnerable to pests and disease. As we battled Covid, so they are currently fighting an unprecedented attack from biosecurity threats. The Royal Forestry Society has recently reported that over one third of Europe’s 454 native tree species are considered threatened. New pests and diseases are mainly arriving in the UK through imports of wood and trees, but it is the soles of our shoes that are providing an easy way for them to spread out around the country. Washing our shoes is therefore a very small ask in terms of protecting our country’s precious biodiversity and landscape.



To understand more about the problem of tree health, I recently went for a walk with Dr Andy Moffat. Andy is an experienced environmental and forestry scientist. Now an environmental consultant, he was formerly Head of the Centre for Forestry and Climate Change at the Alice Holt Forestry Research Centre, between Bordon and Farnham. As well as undertaking research on the likely effects of climate change on woodlands and forests, the Centre also has responsibility for tree pests and diseases.

Our walk was timely, as Andy had recently returned from New Zealand. As an island nation highly dependent on agriculture and forestry it is well known for taking biosecurity very seriously. Fearful that his boot cleaning might not pass muster with New Zealand border control, Andy had deliberately not used his brand-new boots until reaching the country. These had now been freshly cleaned for our walk around a local woodland, as had mine.



Our walk started by following a wide Sweet Chestnut lined avenue. The trees, all veteran and rather cancerous looking, perfectly set the scene for our chat. Andy explained that over the last 40-50 years the UK has gone from having a tree disease or two a decade, to now almost one a year. Many people will have heard of Ash Dieback, and perhaps Sudden Oak Death, but there are many others including Red Band Needle Blight, Horse Chestnut Leaf Miner, and various forms of Phytophthora which affects Chestnut, Larch, Beech, and Sycamore. I mentioned remembering Dutch Elm Disease from my childhood but was corrected by Andy. “That disease is no relic of the past” he said, “the beetle which caused Elm Disease is still very much with us, we just don’t notice it because it takes the trees out long before they reach maturity.”

Signs in woodlands warning about Phytophthora like the one below are unfortunately becoming a common sight. However, without better understanding of these diseases, their causes and consequences, the information fails to resonate with members of the public.



Wanting to better understand the background to the biosecurity problem, I asked Andy to explain how we have got to this point. He said that there are several factors behind the recent proliferation in tree disease, but imports are the biggest problem. However, as the world’s third largest importer of timber, he cautioned that the UK always has to delicately balance the needs of fibre/timber security against that of biosecurity. “Unfortunately”, he said, “we all love our oak furniture and wooden kitchen cabinets, and border control can’t realistically check every single pot or piece of bark for microbes and insects. We have a operate a risk-based system.”

Inevitably, another big part of the problem is climate change, as it is well-known that ecosystems don’t function in isolation. Phytophthora, for one, thrives in wet conditions so will perhaps become a greater problem after the rain of this past winter. Another factor, Andy explained, is that many of our forest stands are based on only one or a few tree species. This makes them more at risk from the effects of pests and diseases, should they target a particular tree species.

Our walk route demonstrated the problem posed by monoculture, first weaving its way through dense plantations of Larch then coming out into an expanse of recently coppiced Sweet Chestnut. We stopped amongst the Chestnut stools to chat with the coppicer. He was busy bundling up the brash for use in a salt flat creation scheme. Every piece of wood, no matter its size, had value. However, while very tidy and uniform, the bundles were a stark reminder of the crude nature of forestry work. This was further highlighted by my asking Andy to explain the methods foresters might employ to combat pathogens that threaten existing woodlands. He said that the options are simple, it basically comes down to a choice between leave, thin or fell. Spraying with pesticides, something that is done in more remote parts of the world, is rarely an option here in the UK due to the risk of chemicals entering water courses and the wider environment.



Down the line, it is clear that foresters also have a fourth option, building in resilience by changing what and how they plant trees, either when establishing new woodlands or in restocking after felling for timber extraction. However, this will take time as trees don’t grow fast. In the meantime, it is down to responsible walkers to play a part in halting the spread. Obviously, washing boots regularly and encouraging others to do the same is something we can all do.

However, if you have an interest in conservation, you might also like to participate in a citizen science project Andy mentioned. It is called Observatree. Observatree is a tree pest and disease resource website, where you can learn how to identify both the pests and evidence of their activity. It is connected to a second website, Tree Alert, where you can record signs of tree ill-health you see on walks. Scientists review this information and follow up, if necessary. The idea is simple. The more eyes out spotting threats, the quicker experts can get on top of them. Simple observations like this can really make a big difference. Back in 2012 the Asian Longhorn Beetle was spotted in Kent and a rapid eradication programme succeeded in removing them from our shores. However, we must remain vigilant.

All walkers care deeply about the countryside. Nature connection is one of the main pleasures of walking. So, the next time you go for a walk somewhere new, do give your boots a quick wash first. Simply think of it as paying it forward to nature and following government guidance on biosecurity.

If you are interested in signing up to Observatree, email: observatree@woodlandtrust.org.uk

by Malinka van der Gaauw

Qualified and insured walk leader, local knowledge forager, landscape literacy teacher and champion of the Western Weald - the overlooked western section of the South Downs National Park. I guide people around the Western Weald, not just showing them the way but enhancing their experience every step of the way.

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