Silver birch (Betula pendula)
|Size||Height: up to 25 m|
Common in the UK.
One of the most familiar trees in the British countryside, the graceful silver birch is a genuine native, having been an early coloniser at the end of the Ice Age. Its papery-white bark – almost pink in young trees – distinguishes it from the downy birch Betula pubescens which has reddish bark that turns grey with age and is usually found in wetter habitats in the uplands. The leaves of silver birch are small and roughly diamond in shape. They are toothed on both sides and borne on slender warty twigs that shiver in the slightest breeze. Saplings also share this tendency to sway in the wind and, traditionally, foresters would remove young birches from plantations to avoid them flaying more valuable trees. As silver birch ages, its bark darkens and becomes rougher and more fissured and prone to attack by the birch polypore fungus Piptoporus betulinus.
Birch wood has little strength as a timber although in the past it was used extensively in the Highlands of Scotland. The Highlanders made almost anything from it, including their furniture and houses. Traditionally, the suppleness of the branches and twigs was exploited for making besoms or ‘witches’ brooms. Smaller versions of this implement, stripped of bark, are still popular as kitchen whisks. Besoms were also used as fire beaters but, today, the Forestry Commission uses a less flammable material. Hardly surprising when you consider that birch bark and twigs are one of the best materials for starting a fire!
Birch is found throughout most of the UK and Europe and across Asia.
This species favours dry heaths, downs and woods, but it will also grow in fens and marshes. It has been planted extensively as a show tree in parks and gardens.
One of the reasons why birch managed to colonise the newly emerging lands following the retreat of the glaciers lies in its abundantly-produced seed, as fine as powder. Even today, it remains what botanists call a ‘pioneer’ species, one of the first trees to occupy suitable ground. That said, it is not a long-lived tree; most specimens die or succumb to fungal attack by the age of 70. However, they do offer protection to slower-growing, longer-lived tree species such as oaks, and where left to regenerate birches can play an important role in helping to nurture a wood.
The catkins appear early in spring and release their pollen in clouds during April. The leaves emerge shortly after, a bright emerald green at first and finally turning golden in autumn.
Birches produce an abundance of sap in spring and a cut stump will continue to ‘bleed’ for weeks. In North America, a species of woodpecker called the sapsucker taps birch trees in spring by cutting small wells in the bark and drinking the sap which oozes out. In the UK, a similar technique is employed by makers of birch tree wine, a drink once believed to have medicinal properties, including those of curing kidney stones and skin complaints.
There are currently no threats to silver birch in the UK.
Due to its invasive nature, silver birch scrub is often the reason why conservation work is carried out on some nature reserve sites. Birch colonises open areas quickly and, when left unchecked, can reduce the conservation value of habitats such as heathland. In consequence, there are no specific projects for conserving the species.
Information supplied by English Nature: