Secrets of the dead wood: ancient oaks hold key to new life


Oaks are the elders of London’s Richmond Park. Some of them are 800 years old and have slumped, bulged and grown cavernous with age. By the time King Charles I visited in 1625 and turned a collection of medieval farms into the royal park we have today, they would have already been veteran trees. A disused medieval track is visible from the way the trees lean into a gentle gully, now grassed over. Richmond Park is something of an open-air museum, and among its most precious exhibits is its dead wood.

Simon Richards, manager of Richmond Park. 'You're planting trees thinking, what's that tree going to be like in 400 years' time?'

Dead wood has many guises and starts forming on the inside of healthy standing trees. As they age, it expands, creating a rich habitat that we still know little about. “How many jobs involve managing assets that are 700 or 800 years old?” says Simon Richards, manager of the park. “You’re planting trees thinking, what’s that tree going to be like in 400 years’ time? That’s a real joy of the job – we’re just a footnote in history.”

England has more ancient oaks than all other European countries put together. This is largely thanks to the long-held obsession of royals and the aristocracy with creating medieval parks to hunt deer, as venison was considered a “noble” meat. Within these landscapes, oaks had space to flourish, and thanks to careful management, Richmond is one of the best places to see them.

But it is a difficult attraction to manage. This national nature reserve and site of special scientific interest (SSSI) is also a popular urban park. Modern London breathes people in – Lycra-clad cyclists, cars, babies in prams and dogs wearing coats. Herds of photographers surround herds of deer.

During the pandemic, visitor numbers swelled. “We’re the only show in town at the moment,” said Richards, shortly before the lockdown began to ease. Last June, staff and volunteers picked up 42 tonnes of litter from the park, an increase of 650% from the previous June. “Don’t get me going on the doggy bags,” he says, not referring to the variety you put food in.

Numbers of visitors to Richmond Park grew hugely during lockdown, with 42 tonnes of rubbish left just in June.

Many feel the elders are not being treated with the respect they deserve. Arthritic old trees shed limbs that make perfect play frames, benches or backdrops for amateur photoshoots. Their gnarled caverns create amazing dens and their bulges give small children a convenient leg-up. Looking at the shiny bits of bark, you can see which parts are most clambered upon.

“Such a small act of picking up a bit of dead wood can destroy a habitat that’s been developing over a number of years. It’s a really difficult issue,” says Peter Lawrence, manager of the royal parks’ Mission: Invertebrate project. “It’s particularly difficult here because it’s such a massive tourist attraction – you’re not just talking to people from the local neighbourhood but to people from all over the world.”

The abundance of dead wood excites ecologists as much as children, and one of the reasons Richmond Park became an SSSI in 1992 is its saproxylic invertebrates (insects that require dead wood for part of their lifecycle). Park wardens changed their management practices and intentionally left out dead wood, letting limbs lie where they fell. In the 90s, Richards got a number of letters from the public complaining that he had “let the park go”, but now visitors have got used to it, he says.

There are 320 ancient oaks in the park, meaning they are more than 400 years old. These are the oldest of the park’s 1,300 veteran trees, which are of an undisclosed age, and starting to develop ancient characteristics, such as hollowing at the base, a smaller crown, and generally becoming wider and squatter. It may sound familiar.

One of Richmond Park's ancient oaks. The trees appear squatter with age and begin to get hollowed out at the base.

Trees of this advanced age might look old and tired, but they have lived so long because of these features, not despite them. Dropping branches and hollowing makes them lighter and more stable. With trees that could pose a risk to the public, temporary fences are put around them, so they can drop limbs in peace – they may still have hundreds of years ahead of them.

As soon as hollows develop, parakeets, owls, nuthatches, bats and other wildlife compete for them. The fact we put up so many bird-boxes is a reminder that cavities – which are natural nesting sites – are missing from our landscape.

As well as natural structures within veteran trees, the dead wood itself is full of life. There can be 280 invertebrates in one large handful of rotten wood inside a tree. Richmond Park has more than 1,000 species of beetle, many of which rely on dead wood, including the nationally rare cardinal click beetle and stag beetle.

However, across the country, dead wood is still being cleared away as people try to make woods “tidy”, or because it’s “dead” and unsightly. In wild, natural woodland a quarter of wood is dead, but in most managed woodlands this is less than 10%, according to the Wildlife Trusts.

Peter Lawrence, manager of the royal parks' Mission: Invertebrate project, points out holes created by invertebrate larvae on a bracket fungus, which would have been growing on a tree.

“To appreciate the different forms of dead wood, don’t think of it as bad or dangerous – all that deadness has a lot of life in it,” says the author and naturalist Steven Falk, who has written a report on saproxylic insects for the Woodland Trust. Falk’s study showed 320 saproxylic insects in the UK also pollinate flowers, 16% of the national total. Previously, it was not known that many saproxylic insects were also pollinators.

If land managers want to protect these insects, many of which are rare, they need to create light-rich habitats around veteran trees so that flowers can grow near them, meaning pollinators have everything they need to complete their life cycle.

Giving a tree space is a bit like providing it with a pension. It means it has enough light to develop large lateral spreading limbs and space for roots to penetrate deep. If an oak can grow old with grace it can provide value for wildlife in many hundreds of years time, not just the next 50. This will be useful information for those planting the next generation of veteran trees.

“We have a bit of a problem about what we perceive woodland to be,” says Emma Gilmartin, conservation adviser at the Woodland Trust, who specialises in ancient and veteran trees. “For a lot of people it’s quite a dark, shady environment, and certain species certainly require those dark shady spots. But veteran trees are refugia for other species that also require lots of light. Flowers are really light-dependent – to get maximum pollen and nectar sources, we need those open spaces within woodland.”

Dead wood and fallen limbs from trees are now left in Richmond Park to help species such as saproxylic invertebrates. They also make handy seats.

Back in the park, Richards is examining an old tree surrounded by oaks planted about 10 metres away from it in the 50s and 60s, at a time when people did not yet appreciate the true value of old trees. He is considering whether to chop down competing branches to give the veteran tree the space it needs to age. Election pledges to plant millions of trees are “all meaningless if you don’t look after them”, he says.

Walking around the park, Richards inspects the health of trees like a doctor might examine human bodies, making note of their fragilities, and where they might need support. With each passing year, old trees become more valuable, entering new, richer phases of life that command more respect. Imperfections are assets.

“People are reluctant to accept the concept of death – we see it in all of us, we want to live for ever. So when you see an old tree, or a dead tree, it’s almost as if we have failed,” says Richards. “But it’s just a natural process, and I think that’s it – it’s not living, it’s dead, it’s evolved, and the habitat has evolved and is just continuing to recycle.”

Find more age of extinction coverage here, and follow biodiversity reporters Phoebe Weston and Patrick Greenfield on Twitter for all the latest news and features


Please enter your comment!
Please enter your name here