The successful immigrant

A widespread and common tree throughout much of the UK, the sycamore (Acer pseudoplatanus) is perhaps a victim of its own success; its very ability to seed prolifically in the disturbed and over-fertile soils of urban areas and agricultural margins has made it, rather bizarrely, the scapegoat of many conservationists. It isn't helped by the fact that it isn't strictly 'native' to Britain, having been introduced in Scotland from France in around 1550. Nevertheless, its obvious ease in our landscape and climate all suggests it would have arrived here under its own steam if the English Channel hadn't intervened. By all accounts it behaves like an honorary native (beech is another tree with a similar history in Britain), and its wider contribution to both wildlife and our landscapes deserves wider recognition rather than the dismissive censure that bedevils it.

The sycamore - literally, and confusingly, 'fig-mulberry' - is a member of the maple family characterised by their soft five-fingered hand-shaped leaves, which develop the striking orange and yellow hues during autumn. However, the large leaves of sycamore have lent it to be erroneously referred to as a plane (pseudoplatanus is 'false-plane', and the Americans call their eastern plane the sycamore, just to muddy the waters further). The tree flowers in May, with large pendulous green panicles providing a rich nectar source for bees, and then during the summer the two-winged fruits are formed. These 'helicopters' aid the distribution of the single seed, and in wind they can be carried up to 250 metres away from the parent tree.

The seedlings grow quickly, and often in densely packed clusters, usually on ground not otherwise colonised by other trees. They particularly benefit from high nutrient soils (such as near the old manure heaps of farms, edges of urban woodlands and railway lines), and are also tolerant of salt, which allows sycamore to flourish in many coastal areas. The sycamore's profligacy can give the impression of invasion, and the justification for their removal from woodlands and other habitats, is that they shade out the competition of our native tree species. Given the soils that sycamore prefer, this is in most cases unlikely, and natural competition would anyway eventually result in a mixed stand of trees - mature monocultures of sycamore are rarely found. It is, if we care to look closely, a successful lesson in immigration.

The tree grows quickly, and can reach 40 metres in height and if the conditions are right, 300 years of age. Despite a few remarkable individuals (such as the Martyrs' Tree, Tolpuddle, Dorset, and the Newbattle Abbey Tree, Edinburgh), most of the sycamores we encounter are considerably smaller, and given the interest in many to see them removed it is perhaps unfortunate that we rarely allow them the chance to grow to the majestic scale we can witness in many European parks ('great maple' is an old, but more accurate, name for the tree).

The wood of sycamore is amongst the best we can grow; hard, strong, and pale. It doesn't taint easily, and its strength and flexibility makes it ideal for kitchenware, dance floors, and stringed musical instruments. They are planted as shelter-belts, and are particularly valuable for the reclamation of contaminated land, such as old coal fields and post-industrial sites. This utility, however, is somewhat hidden by the notoriety they currently enjoy for being 'bad for wildlife', and as a result conservationists often target their removal, despite the fact that their presence in woodlands, for example, is largely natural.

Like most maples, sycamore does not support a wide diversity of wildlife. With a total of about 35 species compared to the several hundred found on oaks and willows, this statistic has been used to 'rubbish' the sycamore. However, the field maple (our only native of the family) supports just over 40, and what the sycamore lacks in variety it makes for up in quantity. Sycamores can be literally dripping with aphids, tapping into the sweet sap in the leaves, which in turn provide a superb food source for blue tit, great tit, robin, wren and other birds. The dormouse (one of our rarest mammals) feed on aphids (hoovering them up from the undersides of leaves), especially during the spring and summer (vital for the nourishment to feed their young), and research in the south-east of England has shown that woods with about 25% sycamore are beneficial for their conservation.

Perhaps more surprisingly, research by a London entomologist has unveiled the sycamore's value to a range of uncommon insects, especially beetles. The orange ladybird (Halyzia sedecimguttata, which feeds on the mildew of sycamore sap) and chequered fungus beetle (Cicones undatus, once highly rare), are just two species for which their distribution appears to be dependent on sycamore. As its status as a host for a range of insects and fungi is better known, there is hope that the sycamore's reputation as an 'alien invader' is re-assessed, and we can eventually appreciate its role within the complex ecology of our woodlands.

Mathew Frith

[Reprinted with permission from the Selsdon Gazette, Mid December 2004 where it was published under the pseudonym Ray Noutria]

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Last updated March 11^th 2005
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