Our guest editor, Nick Gates, Naturalist, writes
Storm damaged trees are hastily sectioned for firewood or bio-fuel. Sometimes, we replace them with a new, younger version of themselves. It was thought that this in turn kept other trees healthy, and that the wider environment benefited as a result.
But nothing is further from the truth. By removing this deadwood, we are stripping out a most vital layer of the natural world. Because when a tree dies, it isn’t actually dead.
As a tree grows, its core begins to die. Have you ever looked at a majestic old oak, its core completely hollowed out, and wondered how on earth it was still producing green leaves and fresh shoots? The reason is that only the outer layers of the wood, just below the bark, are alive. They transport all the water and nutrients that a tree needs to survive. Simultaneously, under the soil, a massive network of fungi around its roots help the tree collect all of the vital nutrients and minerals it needs. As the tree grows, the wood core, the growth rings left behind and superseded from previous season, slowly dies.
Over time, this core wood is slowly broken down by fungi. In the very oldest trees, the core is lost completely. Perhaps the most famous of these wood-feeding specialists is one you may well have eaten, the Shiitake mushroom. The fungi in turn are eaten by many species, from bacteria to nematodes, insects to mammals, whilst the rotten wood supports many more. Therefore, this soft rotting deadwood actually hosts a complex living food web.
An oak tree supports over 350 different varieties of insect. But over half of these feed on dead parts of the oak tree. Bats rely on deadwood cavities to roost, whilst feeding on many species of night-flying beetle that feed solely on deadwood. Redstarts require hidden cavities to nest, whilst searching for bark beetles and moths that grew up in the deadwood. Everything from blue tits to woodpeckers and wood mice to tawny owls rely on deadwood for some part of their existence. By the time an old tree falls completely, upended from its rotting root network, the wood may be dead but the vast diversity of creatures it is feeding are very much alive.
When we strip out deadwood from a natural environment, often under an aesthetic tidiness premise, we aren’t just taking the wood away. We are slowly eroding the complex living food web that the deadwood feeds. The Bristol Downs has suffered from this for many years. We could have hedgehogs snaffling snails from deadwood retreats and spotted flycatchers nesting amongst the craggy cavities in gnarled out stumps. Animals just need food and shelter to thrive. By removing deadwood, we take away both. There are many ways of leaving deadwood that look aesthetic whilst appreciating the enormous ecosystem service it provides. Good signage can help explain this.
In a time of unprecedented ecological collapse, we must all do what we can to help the natural world. Leaving deadwood in situ is one of the easiest ways to do this. So please, next time you see a fallen tree, don’t look on it as an untidy addition to the landscape, but enjoy it as the next opportunity for nature to reclaim a part in our everyday lives.
@NTGates Feb. 2020
Fantastic article, and beautifully written. Thank you , Nick Gates, for letting us picture just how trees are so intricately enmeshed with their environment. It’s incredibly satisfying, and inspiring, to understand how it works, how so many species live their lives on and under and in and around around a tree, how they all fit with each other and the tree, and how we really need to learn when to keep our hands off and stand back and pay attention.
Thanks, Bristol Tree Forum, for educating us again.