Veteran trees, deadwood and the species that need them

Veteran is a description of condition rather than of age. A veteran tree carries the features associated with the later part of its life: a hollowing trunk, decaying heartwood, dead limbs still attached, rot holes, loose and fissured bark, sap runs, and accumulations of wood mould in cavities. Each of those is a distinct micro-habitat used by a different set of organisms.

Fruit trees reach this condition quickly, and that is the point. Where a parkland oak needs centuries to begin offering hollows and heartwood decay, an apple tree can do it within a human working life, and a perry pear does it while remaining productive for another century. An orchard planted in the 1930s is now delivering habitat that a woodland planted at the same time is nowhere near providing.

The scarcity is what gives it value. Decaying wood has been systematically removed from the lowland landscape — felled for safety, tidied for appearance, cleared for firewood — so the species that depend on it have become confined to the few places where it persists: ancient wood pasture, parkland, and traditional orchards. Orchards are the smallest and most fragmented of the three, and in some counties the most important.

The noble chafer is a beetle of about two centimetres, metallic green with a scattering of white flecks, whose larvae live in decaying wood inside old trees — most often plum, apple and cherry in orchard settings. The larvae develop over more than one year in wood mould in the trunk, and the adults emerge in summer and are found feeding on umbellifer flowers such as hogweed and meadowsweet in the orchard and its margins.

It is rare and localised in Britain, with strongholds that include the traditional orchards of Worcestershire, Herefordshire and Gloucestershire and the Wyre Forest area. Because the adults are short-lived and hard to find, surveys rely mainly on searching for the larval frass in rot holes, which is distinctive enough to identify the species from — a survey method that says a good deal about how confined the animal is.

Its situation summarises the orchard conservation problem exactly. It needs old trees with decaying heartwood; those trees exist in quantity almost nowhere except traditional orchards; and traditional orchards have been lost extensively and continue to be. Removing a hollow orchard tree that looks finished is, quite often, removing the only habitat within a considerable distance.

The noble chafer is the most familiar orchard specialist but far from the only one. Traditional orchards support a wider saproxylic beetle fauna, solitary bees nesting in dead wood and in bare ground, and a range of flies and other invertebrates that depend on rot holes, sap runs and decaying fruit. Old orchard bark carries lichen communities that need long continuity, low disturbance and clean air, and the sward supports its own fungal and invertebrate community.

Vertebrates use the same features. Hollows and old woodpecker holes provide nest sites for birds including redstart and little owl, and roosts for bats. Lesser spotted woodpeckers are associated with orchards where old and dying wood is plentiful. Fallen fruit is a substantial autumn and winter food resource for thrushes, including overwintering redwings and fieldfares, and for badgers and other mammals.

The mistletoe growing in the same crowns supports its own dependent invertebrates and feeds mistle thrushes and blackcaps in winter, which is why orchard conservation treats a parasite of the crop as part of the habitat rather than as a problem to be eliminated.

The instinct to tidy is what destroys this habitat. Cutting out dead limbs, felling hollow trees, removing fallen wood and burning prunings all remove the resource. The alternative is not neglect but a different standard of tidiness: retaining standing dead wood where it is safe to do so, leaving fallen limbs on site rather than clearing them, and stacking prunings in a corner rather than burning them.

Veteran trees can often be kept standing for far longer than they look able to. Reduction pruning to lower the crown’s wind resistance and mechanical load, done gradually over several seasons rather than in one drastic operation, extends the life of a tree that would otherwise split. A tree that has already lost limbs and hollowed can be stable for decades if it is not asked to carry a full crown.

Where a veteran tree does have to come down for genuine safety reasons, the wood is worth more on site than off it. Standing monoliths, ground-level stacks and retained stumps continue to provide habitat, and the species using the tree do not necessarily have anywhere else to go. Continuity is the resource: the orchards richest in deadwood species are those where old trees have been succeeded by other old trees without a generational gap, which is an argument for planting replacements decades before they are needed.