Deadwood is not a mess — it is a habitat

Walk through a heavily tidied wood and you can often sense what is missing before you can name it. There are no mossy logs half-sunk in leaf litter, no leaning dead trunks furred with lichen, no tangle of brash at the edge of the ride. For centuries British woodlands have been swept, cleared and burned clean, and the result is that many of our woods are poorer in wildlife than they look.

Decaying wood is one of the richest habitats we have. Around a third of British woodland wildlife depends on it at some stage of its life, and a good deal of that wildlife is now uncommon precisely because deadwood has been removed. The practical message is simple: where it is safe to do so, leave decay in place. It is not untidiness — it is the engine room of the wood.

The creatures that depend on decay

Fungi do the heavy lifting. Species such as beefsteak fungus, candle snuff fungus, dead man's fingers and birch polypore break down lignin and cellulose that almost nothing else can digest, and in doing so they release nutrients locked up in wood back into the soil. Without them, a fallen oak would simply sit there for centuries.

Close behind the fungi come the invertebrates — the saproxylic species, meaning those associated with deadwood. Stag beetle larvae spend several years chewing through rotting stumps underground in southern England, while rarer beetles depend on very specific conditions: sun-warmed wood, damp hollows, or the crumbly red heartwood of ancient trees.

• Birds: great spotted woodpeckers chisel nest holes in standing dead trunks, treecreepers and nuthatches forage along dead branches, marsh tits cache food in soft stumps.
• Bats: barbastelles, noctules and pipistrelles roost behind loose bark and in cracks in dying trees.
• Plants and lower life: mosses, liverworts and lichens colonise slow-decaying surfaces, and new seedlings often establish on rotting stumps — a natural nursery.

Fallen logs and standing dead trees do different jobs

It is tempting to think any deadwood will do, but position changes everything. A standing dead tree is dry and sun-warmed, with cracking bark, sap runs and hollows. It offers nest holes, roost sites and song posts, and its timber decays slowly from the inside out.

A fallen log is a different world. It sits in shade, holds moisture, and stays in contact with the soil, so it is colonised by a separate set of fungi, beetles and invertebrates. Amphibians shelter beneath it, voles run along it, and its gradual collapse feeds the ground beneath. A wood with both — plus a few dead branches still caught in the canopy, and some brash piles at the margins — supports far more life than a wood with only one kind.

How to leave deadwood safely

Safety is really a question of targets: what could be struck if something fell. A dead tree leaning over a footpath, car park, shed or play area is a genuine risk and should be assessed by a qualified arboriculturist. A dead tree in the middle of a ride, or well back from anywhere people pass, is an asset. A few practical rules help:

• Reduce rather than remove. Where a standing dead tree must be made safe, consider leaving a monolith — a trunk cut at three to five metres. It keeps much of the habitat value while removing the risk.
• Keep timber where it grew. Moving deadwood between woods, or bringing firewood in, can spread pests and diseases such as ash dieback and Phytophthora. Leave logs in the same wood, ideally in the same spot.
• Don't burn it all. It is easy to tidy brash into a bonfire out of habit. Leave a proportion in heaps, and keep the bigger pieces on the ground.
• Check before you cut. Dormant season work avoids disturbing nesting birds, and a quick look for bats and roosting holes takes only a moment.

Putting deadwood to work: dead hedges, log piles and craft

Deadwood does not have to be passive. A dead hedge — brash woven between sturdy stakes — makes a durable boundary that also shelters birds, insects and small mammals, and it uses material you would otherwise burn. A stumpery, the Victorian garden trick of upturning large roots among ferns, creates cool, damp shade that fungi adore.

For the craftsperson, there is a distinction worth knowing. Rotten wood is no use for joinery, but dry, sound dead branches can be worked into pegs, tool handles, walking sticks and small carvings, and can be split for rustic rails and benches. Fallen timber also makes excellent garden furniture and raised bed edging, provided it is sound when you cut it. Anything too soft for the workbench is exactly right for the log pile — part-buried in shade, with a few pieces left in the sun to warm through.

A light touch and a long view

Decay is slow. A fallen oak may take fifty to a hundred years to return fully to the soil, passing through stages that each suit a different community of life. That is why the most useful thing you can do is often nothing at all: mark where the deadwood lies, note it in your records, and resist the urge to tidy it next spring.

If your wood has very little deadwood, start small. Leave one log, one stump, one standing dead tree per acre and watch what arrives. Within a season you will see beetle holes, fungal brackets and woodpecker workings. Within a decade you will have a wood that is visibly richer — and all you did was let nature get on with it.