Silver birch - (Betula pendula Roth)

Fact sheet

Range and distribution

Betula pendula is the most widespread tree-sized birch in Europe and in Italy. Its distribution is typically montane, but it ranges from the basal belt up to the subalpine belt. Its range is very wide: to the north it reaches as far as the Arctic Circle, while to the south it gets to Greece, Spain and, in Italy, as far as Sicily. The southernmost ecotype is the variety aetnensis Raf., found in characteristic stands in the vegetation of Etna. In Italy it is widespread in the Alps, at the edges of fields and meadows, on sands and scree slopes, and intermittently in the Apennines: it thins out in the northern Apennines, disappears in Umbria and the Marche, is present in Campania and in small stations in Abruzzo, is absent from Molise and Calabria, and reappears in Sicily.

Ecology

The silver birch is a hardy species. Thanks to its great adaptability, its modest requirements and its ability to improve the soil, it is considered a coloniser species.
In terms of temperature the birch shows great adaptability, although in the warmest areas it is less long-lived.
It has high water requirements because of its high transpiration. However it manages to avoid water stress thanks to its very deep root system and a fast growing cycle.
It is indifferent to soil pH. It is found more often on acid soils because there is less competition from other species there. Being a pioneer and hardy species, it adapts well to the poorest and most degraded soils.
Its light requirements are very high, confirming its preference for poor environments, with mineral soils where competition with more demanding species can hardly take hold.
In the subalpine belt it is found in green alder scrub, in larch woods or at the edge of spruce forests.
In the montane belt it is linked to Scots pine, forms small mixed woods with aspen on abandoned farmland, and joins the beech only in coppices on acid soil.
In the basal belt it is linked to oak woods on acid soils and to abandoned chestnut groves.
The presence of the birch on Etna is closely linked to the activity of the volcano, which keeps giving it new chances to play the pioneer.

Habit

Its habit is light and elegant thanks to the straight trunk and the drooping branches. It generally grows to 15 m, but can reach 30 m.

Leaves

The leaves, triangular in shape, are 2.5 to 7 cm long, with a straight base, jagged double-toothed margins, and a hairless petiole and underside.
They are thin and decompose quickly, enriching the soil to the benefit of more demanding species.
In autumn they turn yellow before falling.

Flowers and fruit

 

The male inflorescences (catkins) are purplish brown, while the female ones, smaller, are green and open in April.
The infructescences stay on the tree until December, then break up into scales and very light winged seeds that are scattered by the wind.

Bark

The bark is one of the features that make the silver birch most recognisable. In fact it is also known as the white birch because of its typical silvery-white colour with dark angular cracks or ridges. See a photo of the bark...

Uses

Birches have always been precious to mountain peoples, providing leafy branches, bark, wood and sugary sap. The wood is not used in industry because it is not very durable and comes only in small sizes. It is used to make brushes, tools and turned work. It is an excellent fuel. The branches are used to make garden brooms. The leaves and the bark have dyeing properties. An oil is extracted from the bark that was used in tanning leather and as a medicine. Also, by cutting into the bark, a sugary sap was obtained. Fermenting this sap produced an alcoholic drink and vinegar. It was a sacred tree for the Celtic peoples. Thanks to their habit and their capacity for intraspecific hybridisation, the species of the genus Betula are among the most widely grown ornamentals in the world. It is a species used for consolidating the soil, together with alders and willows.