Everything you need to know about dead wood

Did you know that a key part of any wildlife garden is dead wood? You may not have thought it, but dead and decaying trees and plants can actually provide rich habitat for a number of species.

Here’s everything you need to know about dead wood: why it’s important, what lives in it and how to use it in your garden.

Stag beetles might look ferocious, but they are not poisonous and don't bite. These threatened deadwood experts could only give you a firm nip. Photo: Ben Andrew (rspb-imags.com)

What is dead wood?

The stump of a cut fallen tree, a standing dead tree, dead branches on a tree, a fallen branch lying on the ground – there are lots of different forms of dead wood. Dead shrubs are also considered deadwood. They are all valuable for wildlife.

Here’s how dead wood is made:

1. Trees are composed of living tissue with a protective bark layer. Surrounding tissue underneath is a layer of xylem vessels. These vessels transfer water and nutrients from the roots to the canopy. 

2. As a tree ages and grows it lays down new vessels beneath the bark. The old inner ones die. This inner dead wood, known as heartwood or ripewood, is protected from decay by the outer bark.

3. During the normal aging process of a tree, things will happen to expose this heartwood. A limb may fall off in a storm, or a woodpecker may bore a hole. When this happens specialist fungi begin the decaying process. The fungi hollow out the tree and creating good habitat for deadwood invertebrates. 

The older the tree, often the rarer the species it supports. As ancient trees can have amazing microhabitats not often found elsewhere.

Holes in dead wood provide nest sites for bats and birds. Photo: Michael Harvey (rspb-images.com)

Why is dead wood important?

Dead wood is packed with nutrients and it’s a great home, too. There are a whole host of species that live in it, eat it and eat the things that live in it. Plus, it’s good for the environment...

Dead wood slowly releases a steady flow of nutrients into the soil as it decays, feeding the plants around it. It also stores carbon. And it can make soil more stable.

Insects live in dead wood. And they in turn feed birds and mammals.

Decaying wood also contains lots of holes, which provide a home for nesting birds and bats. And it’s soft and easy to excavate, so animals can make holes when they can’t find any.

Dead branches provide a clear, visible perch for displaying birds looking for a mate. 

And dead wood slows streams – preventing erosion and providing food and cover for fish.

So why do we need to look after old bits of dead wood? Because we're losing it: the loss of traditional woodland management techniques, the use of pesticides and people 'tidying up' have all contributed to a decline in dead wood habitats. 

Species such as the aspen hoverfly rely on dead wood. Photo: Jane Sears (rspb-images.com)

What lives in dead wood?

A huge number of species. The UK has around 2,000 invertebrates that are saproxylic – that is, reliant on dead or decaying wood for part or all of their life cycle. Insects bore in, feasting on the dead matter. They’re hidden, insulated and protected. Some live in it, others lay their young in it, or parasitise others that do. Here are just a few:

- Beetles: stag beetles, cardinal beetles, oak jewel beetles, lesser stag beetle

- Boring beetles: furniture beetle, death watch beetle, powder-post beetles.

- Hoverflies: aspen hoverfly, pine hoverfly

- Moths: red belted clearwing moth

- Wasps: chalcid wasp

- Fungi: orange spot, candle snuff

When the heartwood is exposed, the dead tree hollows out. Photo: Ben Andrew (rspb-images.com)

How can you create dead wood?

Losing our dead wood is threatening many species, so it needs to be replaced. Reserves such as RSPB Sherwood Forest are working to protect ancient woodland, and also manage it to ensure there is future dead-wood habitat.

It is possible to artificially recreate these dead-wood habitats. At the RSPB, we do this by cutting off a limb from an old tree, or removing a ring of bark around the trunk or a limb. This exposes the wood inside and creates dead wood earlier in the lifecycle of the tree.

You can make dead wood in your own garden by:

- Leaving dead trees and shrubs standing.

- Removing a ring of bark from any unwanted trees or plants to kill them.

- Removing a ring of bark from a limb or stem of a tree or shrub to kill one part of it.

- Leaving old stumps.

Keep standing dead wood in your wildlife garden. Photo: Andy Hay

How to make a dead wood pile

Yes, your cut logs are vital deadwood habitat too. Make a pile of cut logs, pulled up shrubs and other plant debris in your garden. It will provide an amazing home for nature.

- Choose a spot in your garden that gets light shade.

- Pile cuttings from trees, shrubs and herbaceous plants. Big pieces are best, but you can add smaller pieces too.

- Make sure it is in direct contact with the ground.

- Use a mixture of different woods for best results.

- Pack it tightly to maintain humidity.

- Keep adding to your pile over time.

- Add leaf litter to attract hedgehogs.

…and on balconies or terraces?

Make some small holes in an old bucket. Fill it with a mix of wood chippings and soil. On a balcony, it can stand among tubs and planters. This can be filled with a mix of soil and hardwood chippings.

You can also place logs among planters, or even part bury them as a feature in a tub.

Bundles of dead stems can provide a home for bees. Photo: Andy Hay

7 other ways to include dead wood in your garden:

1. Drill holes in a few logs and set them in a sunny spot for solitary bees.

2. Make larger holes in stumps and old trees to provide nesting holes for bats and birds.

3. Pile logs and leaves to make a hedgehog house.

4. Make some drainage holes in an old bucket. Fill it with stones, then soil, then hardwood chips. Bury it in the garden to provide a home for insects.

5. Partially bury logs vertically in the ground for insects to bore into. 

6. Make dead wood sculptures. You can position these among plants in flower beds. They’ll look good and provide homes for nature.

7. Tie dead stems into bundles and hang them. They’ll work as nests for solitary bees.

You can learn more about dead wood in your Autumn issue of Nature's Home, where we explain how we're caring for veteran trees in Sherwood on page 72.

Do you use dead wood in your garden? Let us know how it's going in the comments below.