Deadwood is habitat, not mess

A dead trunk is not waste awaiting removal. From the moment a tree weakens, a succession of organisms begins that lasts for years. Some fungi colonise standing wood, others appear after the bark falls away, and others again only once the log softens and merges with the soil. Decay releases nutrients back into circulation and creates microhabitats for invertebrates, mosses and seedlings.

The volume of deadwood alone does not describe its full value. Tree species, diameter, position, exposure to sun, moisture and decay stage all count. A few thick logs at different stages provide more niches than an equivalent pile of thin branches. Meta-analyses show a relationship between the amount of deadwood and the diversity of saproxylic organisms, but they also show the importance of the quality and continuity of the resource.

Not every retained trunk is the right answer in every situation. Beside roads, buildings and active protection of particular habitats, a manager takes safety and the purpose of the site into account. In a commercial forest, however, it is possible to retain habitat trees, sections of thick wood and places left without intensive tidying.

For an observer the most important thing is not to break this habitat apart. We do not roll heavy logs over, we do not tear off resupinate fruiting bodies, and we do not take the whole specimen away for identification. A photograph should include the wood, the growth habit and a scale. In the Białowieża Forest similar structures can be seen in a natural arrangement; it is continuity, rather than a single "handsome bracket", that creates the exceptional diversity.

What the meta-analysis found

Lassauce and colleagues isolated 46 studies relating deadwood volume to richness of saproxylic fungi and beetles. The association was positive but moderate—r = 0.31—with no publication-bias signal in the test used. It was stronger in boreal than temperate forests, while differences between logs and standing deadwood and among decay classes were smaller. This quantitatively supports retaining deadwood, but argues against one universal m³/ha threshold. The synthesis combines stand-level correlations rather than randomised experiments, so it does not show that adding any wood will by itself recreate a community. Management should record volume together with tree species, diameter, form, moisture, decay stage and landscape continuity. Tropical systems and later decay stages were not evenly represented.