Intro

Have you ever walked through a planted woodland, with it’s straight rows of trees, and thought ‘there’s nothing here!’ well, there could be many reasons for this, however, one reason I’ve noticed is a lack of dead wood.

Invertebrates are not what we usually refer to as ‘charismatic species’ like a badger or hedgehog in the UK; however, being positioned near the bottom of the food chain means that an increase in invertebrate diversity will lead into more noticeable increases in the bigger charismatic species we all know and love.

Saproxylic invertebrates are highly specialised and dependent on deadwood habitats, often associated with particular forms of fungal decay. Many are rare or uncommon species and can be poor at colonising new areas. Around 2000 invertebrates rely on dead wood. In the UK as much as 650 beetles rely on dead wood alone. UK also has thousands of fungi species, many of which can be found on trees and deadwood.

However, dead wood is often overlooked as it is associated with looking ‘messy’ or being waste or unsafe. In this article we will give a summary of the usefulness of deadwood for increasing biodiversity and ways you can achieve this on your site or within biodiversity enhancements reports.

Breaking it down

Wood is typically composed of about 25% lignin, and 70% cellulosic carbohydrates, with roughly 45% cellulose and 25% hemicelluloses. All of these various compounds, which are naturally very tough due to their over-lapping fibres, are able to be broken down by fungi; which will break them down into edible sugars which beetles and beetle larvae can digest (as well as eating the fungi itself). Life is a process of transferring energy; by removing a dead limb of an oak from a site, is therefore removing several tonnes of energy which could otherwise be transferred into the ecosystem.

Life and Death of a tree

Lets take a look at some interesting examples of the trophic levels (food chain) which result from dead wood.

Lemon Slug

A stump in an ancient woodland has been decaying for many years and is being decomposed by one of the last fungi to attack rotting wood, the candlesnuff fungus (Xylaria hypoxylon). A rare and striking lemon slug – Malacolimax tenellus – an indicator species for ancient woodland emerges. Only emerging for a few weeks of the year, in the Autumn, the lemon slug mates and feeds on mushrooms, such as the below candlestick fungus. The lemon slug is a very under studied species in the UK with very little data. Try looking for them in the Wyre forest and other ancient woodlands in the UK.

Malacolimax tenellus, The lemon Slug
eating Candle-snuff fungus
© Rosemary Winnall

Noble chafer

The noble chaser (Gnorimus nobilis) is a rare metallic green beetle which can be found in traditional orchids in the south of the UK (and across Europe), in very old and decaying fruit trees. They can take up to 3 years to develop into an adult whilst in these old trees. The beetles feed on the decaying wood which can be found in hollowed out boughs of old (50-80 years) apple and cherry trees.

It’s not just about nutrients though…

Many more species use the structural benefits of dead wood, woodpeckers, bats and arboreal mammals, badgers scratching the wood, marking their territory, a displaying or lookout perch and shelter for many more species from ants to hedgehogs. Deadwood standing and fallen is therefore a great way of increasing structural complexity.

Conclusion

Recently, local councils are beginning to include dead wood as a valuable habitat in their planning decisions and works, including it within their biodiversity net gain recommendations. Dead wood is also included in the higher level stewardship scheme, up to £300 per tree: TE13: Creation of dead wood habitat on trees.

There is evidence to indicate that standing dead wood may yield more biodiversity than deadwood on the ground therefore if a tree has to be felled for unsafe limbs, leaving the monolith standing, which is often deemed safe after limbs have been removed, is a good substitute which you could consider for your site, or within your ecological reports.