Somewhere in the region of 1,800 invertebrate species in Britain depend on dead and decaying wood at some stage of their lives. That is before you count the fungi, the lichens, the mosses and the bats, birds and small mammals that nest, roost or feed in it. Deadwood is not a niche interest within conservation. It is one of the largest single habitats we have, and one of the least talked about.
It is also one we keep removing. I spent ten years at one of Europe's largest landscaping companies, which gave me a good view of what happens when a tree comes down, whether it is storm damage, ash dieback, a development clearance or routine management. The timber rarely stays where it fell. Most of it goes to a chipper or a biomass boiler. The logic is easy to follow, because it is tidy, it is quick, and it feels like a use for something that would otherwise be waste. But a log that is burned or shredded within weeks of felling has provided nothing to the wildlife that would have colonised it over the following decades. The habitat is gone before it has had a chance to become one.
Figure - This chart illustrates how large sections of deadwood can take decades to decay which is why hundreds and thousands of species have evolved to exploit certain stages of this process.
The same instinct shapes how we look after most landscapes. Grass is cut short, fallen branches are cleared from under the trees, old stumps are ground out, and dead standing trees are felled the moment anyone raises the word safety. In a business park or a housing estate, a log pile can look like a job someone forgot to finish. I understand why people feel that way, and I have felt it myself. But a landscape kept entirely clean is a landscape with nowhere for a wood-nesting insect to start.
What makes this harder is that deadwood is not one thing. A standing dead trunk in full sun, warmed from morning until evening, supports a completely different community from a log lying in the shade of a hedge bottom. Wet wood and dry wood are different habitats. So are wood buried in the ground, wood half buried, wood lifted clear of the soil, and wood still attached to a living tree. Each stage of decay brings in a different set of species, and many of them need several of these conditions at once, or need them in sequence across their lives. A larva might spend two years in damp rotting heartwood and then emerge as an adult that feeds on flowers in the sun. If you only provide one kind of dead wood, you only provide for one part of that story. What we need is variety, and plenty of it, in the same place.
Figure - A bee posts stands tall next to a log stack within an area of long grass at Manchester City Football Club
That is the thinking behind what we have been doing at Niche for the last five years, which is making bee posts. On paper the idea is simple. A post of timber, drilled with a range of hole sizes, set upright in a sunny position, offering the kind of warm, dry, stable nesting cavity that a standing dead tree might once have provided. I have been drilling holes in timber for ten years now, and it has still managed to teach me more than I expected.
The first thing that surprised me was speed. I had assumed that a new nesting structure would take a season or two to be discovered, and that we would be telling clients to be patient. That is not what happens. Posts installed in spring have often had bees and wasps investigating them within days, and nesting within weeks. Sealed holes, the mud plugs and chewed leaf caps that tell you a female has finished provisioning, appear remarkably quickly. There is clearly a great deal of unmet demand out there, with females searching for somewhere to nest and finding very little.
Figure - Nest cavities displaying different nesting materials used by solitary bees and wasps within a Niche Bee Post at the University of Salford
The second surprise was the range of species. Over five years we have recorded blue mason bees and orange-vented mason bees in the spring, large scissor bees, large-headed resin bees and leafcutters working through the summer, and a run of solitary wasps that most people never look at closely. Among them is the Mexican grass-carrying wasp, a relative newcomer to Britain that stuffs its nest tunnels with grass and provisions them with bush crickets.
This year was the most interesting yet. We documented a good number of wasp species using our structures, including the spider-hunting wasps of the genus Trypoxylon. These wasps hunt spiders, paralyse them and pack them into a hole as food for their larvae. And where there is a Trypoxylon nest, there is often something else waiting. We also recorded Trichrysis cyanea, a sparkling, metallic blue-green wasp and a kleptoparasite, whose host is the Trypoxylon. She slips into the nest while the owner is away and lays her egg there. Her larva then feeds on what the rightful occupant had provisioned.
Figure - A leafcutter bee and Trypoxylon wasp build their nests inside a Niche Bee Post
That is what fascinates me most, because a bee post is never just a bee post. The moment you have a concentration of nests in one place, you have created a small ecosystem, and everything that makes a living from bees and wasps turns up. Cuckoo bees wait for the owner to leave before entering. Tiny parasitic wasps lay through the nest walls. Flies, beetles and mites all have their own way in. Spiders and earwigs use the empty holes and the crevices in the bark, and birds know a good food source when they see one. Open up a post at the end of the season and you are looking at a full food web, with hosts, predators and parasites, in a piece of timber you could hold in your arms.
All of it happens inside holes in a standing piece of wood, and it confirms what we have come to know: standing deadwood is critically important for complex invertebrate communities. I find that both humbling and reassuring. It is humbling because none of it needs us. All we did was provide the wood, and the rest arranged itself. It is reassuring because it shows how quickly life responds when something that was missing is put back. A dead tree takes decades to reach the stage where it offers this kind of habitat, and a well-made, well-placed post can do a version of that job in the first year.
I would not claim a bee post replaces a veteran tree, and it should not be an excuse to remove one. It is a way of making sure that when a site does not have standing deadwood, it can still have something. Alongside it I would always want to see log piles left to rot, stumps left in place, and a bit more untidiness at the edges. The best outcome is the whole range of deadwood I described earlier, not a single structure. But if you are an architect, a landscape designer, a developer or a landowner working on a site where the trees are already gone, a bee post is one of the fastest ways I know of to bring wildlife back into it.
This World Habitat Day, my suggestion is a modest one. Next time a tree comes down, ask where the wood is going. If the answer is the chipper, ask whether some of it could stay. And if you want help thinking about how to build deadwood habitat into a project, I would be glad to talk.
