Why dead wood is worth keeping

Leave a branch to rot quietly in the corner of a garden and you will soon be playing host to a small, spectacular community. A decaying log pile is one of the richest habitats you can make, and one of the cheapest. As the wood breaks down it holds moisture, stays cool in summer and buffers the frost in winter, which makes it a stable refuge for creatures that cannot cope with the open air.

Britain has lost a great deal of its dead wood. Tidy gardens, cleared woodland and the habit of burning fallen timber have left many invertebrates short of somewhere to live. Hundreds of our beetle species depend on rotting wood at some stage of their lives, and some, such as the lesser stag beetle, spend years inside a single log. Add fungi, woodlice, centipedes, frogs and the occasional hedgehog, and a pile of old logs starts to look less like rubbish and more like infrastructure.

Pick a spot in cool, damp shade

Position matters more than size. Damp and shade are what make a log pile work, so aim for a spot that stays cool for most of the day.

• The north or east side of a hedge, fence or shed, where the sun rarely reaches the wood directly.
• Under a deciduous tree, in dappled shade rather than deep, bone-dry gloom.
• Near a pond, in a damp hollow or at the foot of a bank. Amphibians will use the pile as a daytime refuge and commute to the water after dark.
• Away from the house and any timber-framed outbuilding. Keep at least a couple of metres clear of structural timber, and further if the ground is wet.

Once built, the pile should stay put for years, so do not site it where you plan to plant, dig or park a wheelbarrow. On a slope, tuck the base into the soil so the lower logs stay in contact with damp earth.

Sourcing wood without harming wildlife

Almost any untreated wood will do, but native broadleaves rot most hospitably. Ask a tree surgeon, a neighbour with a chainsaw or your local council's parks team, and keep an eye out after gales.

• Good choices: oak, beech, ash, birch, willow, apple, hawthorn and other native broadleaves.
• Leave the bark on. It shelters beetles and holds moisture underneath.
• Mix the sizes. Thick logs of 20–40cm across rot slowly and last for years; thin branches break down in a season or two and give quick results.
• Avoid treated timber — decking, fence panels, railway sleepers and tanalised offcuts. The preservatives are there to stop rot, which is precisely what you want.
• Do not collect from ancient woodland, nature reserves or SSSIs. That wood is already working, and moving it risks spreading tree diseases.

Building the pile

Start with the biggest logs directly on bare soil, never on paving, gravel or a membrane. Contact with the ground lets fungi and soil invertebrates in, which is the whole point. Press the bottom layer down so it sits half-buried.

Stack the rest loosely, criss-crossing the logs so plenty of gaps remain. A tight, tidy stack rots slowly and offers few hiding places; a slightly chaotic heap is far better. Aim for something roughly 50–80cm high and a metre or two wide — bigger is better, but even a modest pile earns its keep.

Finish it off with a few handfuls of leaf litter, some moss and a little soil scattered through the gaps. Add a couple of flat stones or broken terracotta pots at the base for frogs and toads, and consider sinking one or two logs upright alongside the pile as standing deadwood. Never add grass clippings or kitchen waste; they turn slimy and sour the whole thing.

Keep it damp and leave it alone

The single most useful thing you can do afterwards is nothing at all. Resist the urge to tidy, turn or rearrange the pile. Rotting is the objective, and every disturbance sets the community back.

• Water the pile with a canful or two during long dry spells in summer, especially in the first year.
• Top it up occasionally with fresh logs, but never clear out the old ones.
• Leave the fungi alone. Bracket fungi, candle-snuff and slime moulds are all part of the process.
• Check before you move anything. Hedgehogs, toads and newts hibernate in log piles, so if you must disturb it, do so in mild weather in spring or autumn — never during a frost.
• Make sure it is nowhere near a planned bonfire.

What you might find

Colonisation begins within weeks. Woodlice and millipedes appear first, followed by centipedes hunting them, then beetles and their larvae, hoverfly larvae and craneflies. Frogs, toads and smooth newts will shelter under the lower logs, and a robin or wren will soon learn to work the leaf litter at the edges. Great crested newts are fully protected, so if you find one, leave it be and seek advice rather than moving it.

Give it two or three years and the fungi will arrive in earnest, threading white mycelium beneath the bark and pushing up brackets and toadstools after rain. A good log pile quietly improves for a decade before it finally collapses into a soft mound of humus — at which point you simply start another one beside it.