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| Forest 44 is right on the cutting made for the parkway (bottom left) |
The Friends of the National Arboretum Canberra run training for potential NAC guides. During the training each guide prepares two short presentations. Forest 44 was one of mine, as it is planted right at the parkway, and I'd been driving past it every day for long enough to become curious about it.
Forest 44 demonstrates particular methods of forest management and preservation: it is a mixed forest, planted with
Silver Birch (
Betula pendula subspecies
pendula) and
Spanish Birch (
Betula pendula subspecies
fontqueri).
Date Planted: August 2008
Origin of the species name:
Betula is the Latin name for the genus and is derived from the ancient Gaul word for ‘pitch’ which refers to the bituminous content of the bark,
pendula is Latin for hanging and refers to the drooping growth habit,
fontqueri is named after the Spanish botanist Puis Font i Quer.
Family: Betulaceae
Height 25m
Spread 10m
Natural Occurrence:
Silver Birch (the subspecies
pendula)
occurs naturally in almost all countries of Europe from the Mediterranean to Scandinavia (it is the national tree of Finland).
Spanish Birch (subspecies
fontqueri) is rare and is native to three mountain systems in Spain and the Rif Mountains in Morocco.
Natural Habitat:
Silver Birch is most abundant in northern Europe, in almost continuous mixed forests and in fairly large pure stands. In the western and southern parts of the range it is patchy and in the south silver birch is found mostly at higher altitudes.
Spanish Birch is found in small populations in dry woodlands in three mountain systems in Spain and the Rif Mountains in Morocco.
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| Spanish Birch: Young, and in focus |
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| Silver Birch: Green and kind of blurry |
General Description:
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| Spring 2013 |
Both are a medium sized deciduous tree. The bark of the young trees is grey, smooth and shiny and then goes white. The serrated triangular leaves give a bright yellow autumn display. The flowers are wind-pollinated catkins which come out before the leaves in early spring and produce small winged seeds. The subspecies have different seed characteristics.
Conservation Status:
Silver Birch (subspecies
pendula) is not classified as a threatened species.
Spanish Birch (subspecies
fontqueri)
is classified as endangered. The subpopulations are small and dispersed and the spread of housing developments, as well as decline in water availability, fires, cutting and tourism, pose serious threats. A reintroduction program is being developed at Cordoba Botanic Garden, Spain.
Forest 44:
The
Silver Birch is planted around the outside of the forest. The seeds used for the
Spanish Birch specimens grown here were collected from around Granada. They are planted in the middle of forest 44, surrounded by the
Silver Birch for protection.
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| The original cluster of Spanish Birch |
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| Hola |
They are wind pollinated, so the host forest of
Silver Birch on the outside contaminates the seed of the
Spanish Birch, but in time, after all the
Silver Birch have been replaced, the
Spanish Birch seeds produced will have the correct genetic make-up. In the meantime, new
Spanish Birch can be grown from cuttings from the original population planted here. They will eventually replace all of the
Silver Birch - you can already see where alternate trees in the northern rows of the
Silver Birch have been removed and replaced with
Spanish Birch.
Uses:
Silver Birch is grown for timber and pulp in Europe, and is a popular landscaping tree in southern Australia. They are suitable as a canopy tree or a secondary in the garden, doing well in acid soils. The sap can be tapped (4 – 7 litres in a day) – it makes a pleasant drink and it can be fermented into a beer. The bark was used to make baskets and shoes and as an alternative to paper, and the inner bark was used as a ‘famine food’ where other forms of starch were unavailable. The leaves can be used to make a tea that has a diuretic effect.
Further reading:
Rushforth, K. (1999). Trees of Britain and Europe. Collins.
