Field maples generally live for no more than 350 years. However, mature specimens often display characteristics that might lead you to believe they are far older. The shapes and proportions of trunk, limbs and branching are reminiscent of the grander ancient oaks which can reach ages of 800 - 1000 years; a squat, gnarled trunk with a wide base that seems to hold the ground like a clenched fist, pitted with holes and fissures, cored and hollowed by the action of wood-boring beetles and decades of fungal decay. In parts of Northern England, the maple is known as 'dog oak', a nod to the superficial resemblance of the two species' compact, yet rugged form.
The aged features of veteran trees make them particularly valuable to wildlife in a way that their sapling progeny cannot compete. Dead wood branches, hollow trunks and holes provide a wealth of microclimates and habitats for a huge range of creatures. Greater-spotted and green woodpeckers take advantage of soft dead wood, creating holes within the tree to nest, and gaining easier access to the juicy grubs and invertebrates residing beneath the bark. As natural architects the woodpeckers will eventually move on to new projects, allowing new tenants to utilise these warm, sheltered spaces. Many different species of bats, and birds such as starling or nuthatch, will find a snug space to hibernate or roost in the winter, and raise their broods in spring.
The Willsbridge maple has been managed as a pollard which has likely extended its life span and allowed the tree to develop important veteran features whilst still encouraging the regeneration of fresh, healthy growth of limbs and branches. Pollarding involves cutting branches back to a defined point at each bough, traditionally every decade or two. As a response to the loss of limb, the maple sends out a series of fresh shoots in a ring around the amputation, growing tall and straight in a bid to reach the sunlight. You can see this effect in the Willsbridge Valley maple quite clearly. Five proportionally lengthy limbs extend from its thick base, spaced equidistant from each other keeping the tree balanced and allowing the leaf-bearing branches to extend their photosynthetic network outwards, converting sunlight into food, and closing the canopy once more.
The field maple is our only native species of maple so the tree provides food sources for a wealth of native wildlife. Moth caterpillars, such as the maple pug, the mocha and the small yellow wave, all feed on the tree’s succulent spring leaves, each leaf with its five softly-edged lobes. Meanwhile, bees feast on the pollen and nectar reserves provided by the tree’s small hanging flowers. The sap has a particularly high sugar content, making it attractive to aphids (and indeed people who may make syrup from field maples). Aphids in turn provide an abundant food source to a myriad of predatory insects like ladybirds, parasitic wasps and lacewing larvae. Come autumn the canopy develops a wonderfully rich golden hue that allows you to pinpoint field maple within a stretch of species-rich hedgerow or scrubby woodland edge.
The field maple is an important, if somewhat overlooked contributor to the British landscape. Whether they are occupying space beneath the canopy of oak and ash trees in our woodlands, lying low as a shrub, adding diversity to our hedgerows and rich colour to our parks, they are a valuable and adaptable part of our natural and cultural heritage.
Willsbridge Valley nature reserve, near Bitton village on the A431, is open to the public all year round.
Field maple tree (c) Roger Cornfoot - Field Maple - CC BY-SA 2.0