Without dead and decaying wood, our woodlands and urban forests would quickly start to look different; it’s no wonder there’s a growing movement to preserve deadwood around the world.

With correct and careful management, deadwood is hugely beneficial to wildlife, waterways, and the wider ecosystem. With more woodland experts making it a focal point of forest management, you might start to see even more fallen logs and standing deadwood on your walks.

But what is it, and where does its value lie?

What is deadwood?

The term 'deadwood' refers to any wood from a tree that is dead or decaying. Fallen deadwood can be wood that has naturally fallen from a tree or wood from trees that have been felled. This could include loose branches, flaked bark, or even fully toppled trees. After they have fallen, dead trees are referred to as logs.

Standing deadwood is quite different in that the tree is still fully standing, but is gradually decaying. These hollowed-out skeletons are vulnerable to the elements, especially the wind, and need to be carefully managed in order not to cause harm to their surroundings. They are valuable to woodland wildlife, and while they are mostly referred to as snags, they are also sometimes called wildlife trees. Decay is a natural part of the life cycle of trees, and they can survive for hundreds of years in this condition.

You may be familiar with other kinds of deadwood, like decaying stumps or roots left behind after trees have fallen. A considerable amount of wood exists below the surface of the ground, making stumps and roots very important to wider ecosystems by giving fungi a place to grow, and providing habitats for invertebrates and ground-dwelling species.

Supporting wildlife

Standing decaying trees can host a wide range of species from roots to crown, with logs valuable to ground-dwelling species. Both types of deadwood create microhabitats for a vast amount of woodland wildlife.

A huge number of woodland dwellers are saproxylic, meaning they are reliant on dead or decaying wood; in fact, deadwood supports up to a fifth of woodland species, and 13% of all plants and animals known in the UK are directly dependent on deadwood habitats.

This includes 2,000 of the UK’s invertebrates and hundreds of beetle species. It is believed that there are around 650 different species of beetle that require deadwood at some point in their lifecycle.

And it’s not just insects! Several woodland birds have evolved through time to help them extract invertebrates that live in deadwood to feed on. Woodpeckers in particular are fond of deadwood, as the softened, decaying wood makes it easier for them to peck holes to nest in.

The deadwood in our woodlands is also beneficial to the UK’s dwindling bat population. Our largest bat species, the noctule, is known to roost in holes created by woodpeckers once they have fled their nests, and the rare barbastelle bat is only found in woods with plenty of standing deadwood available to them, as they prefer to roost behind the loose bark flaking away from the decaying trees.

Rivers and waterways

Fallen deadwood is vital for keeping rivers and waterways that run through our woodlands and urban forests healthy. The deadwood works as a filter to improve water quality as it filters out pollutants, as well as removing and oxygenating silts. Additionally, the fallen deadwood helps make the waterways safe and secure for those who live nearby, by stabilising banks and beds, and slowing river flows, meaning the logs can act as natural flood defences.

The deadwood found in and around waterways provides diverse habitats for water-dwelling species. Forming different habitats like pools and chutes, logs create microhabitats which add complexity to the waterway. These microhabitats will support a wide variety of species, like fish such as brown trout, frogs, water voles and even otters in some parts of the country.

Fabulous fungi

Without multiple species of fungi, deadwood would not break down. The various forms of fungi that grow on dead and decaying trees release enzymes, aiding in the decomposition process, making the wood soft enough for wildlife to utilise it. Without this breakdown, beetles would be unable to lay eggs, bats wouldn’t roost under bark, and invertebrates wouldn’t be available to the birds. Fungi truly are the unsung heroes of our woodlands!

A lot of fungi species look a little strange, which makes them easy to spot when walking through the woods. Next time you take a woodland stroll, remember to keep an eye out for species like turkey tail and chicken of the woods.

Support for the wider ecosystem

Without the presence of decaying trees, we may not have thriving woodlands and urban forests at all. Large live trees act as carbon sinks, absorbing carbon as they grow, taking harmful gases out of our atmosphere. When trees die, though, this carbon needs somewhere to go.

As dead trees decompose, they slowly release carbon dioxide and other nutrients back into the soil, essentially acting as a natural fertiliser, making the soil around them ready for new saplings to grow. As the nutrients released by decaying trees can be used again and again, a healthy ecosystem can develop without much input from humans. Deadwood plays a very important role in keeping our woodlands healthy and happy, long after it has stopped living.

How do Trees for Cities use fallen trees?

Utilising deadwood doesn’t just need to happen in rural woodlands; it can be used for a variety of projects that will benefit wildlife, especially in urban areas.

At Trees for Cities, we often use logs in our work in school playgrounds as part of our Trees for Schools projects. In the past, we've used logs to create fencing, support new play equipment, and reinforce seating. Not only do these natural elements look great, adding interactive elements for the children using the playground, but they might also attract some interesting wildlife too.

It turns out dead trees are anything but!