Ham Down Woodland
Bere Marsh Farm
Tel: 01258 860284
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Silver Birch (Betula pendula) is a medium deciduous tree, typically reaching 15-25 m tall, exceptionally up to 39 m , with a slender crown of arched branches with drooping branchlets. The bark is white, often with black diamond-shaped marks or larger patches at the base.
The shoots are rough with small warts, and hairless, and the leaves 3-6 cm long, triangular with a broad base and pointed tip, and coarsely serrated margins. The flowers are wind-pollinated catkins, produced before the leaves in early spring, the small (1-2 mm) winged seeds ripening in late summer on 3-5 cm long catkins.
Silver birch is distributed throughout almost all of Europe and in Asia Minor. As pioneer species, one of the important functions which birch trees fulfil in ecosystems is that of improving soils. They are deep-rooted, and their roots draw up nutrients into their branches and leaves, which the trees use for their growth.
Some of these nutrients are returned to the surface of the soil each year when the leaves fall in the autumn, thereby becoming available for other organisms in the forest community. An indication of the scale and significance of this nutrient cycling can be drawn from the estimate that birch trees will produce between 3 and 4 tonnes of leaf litter per hectare per year. Birches support a large community of insects and other invertebrates, with 334 species known to feed on them. The invertebrates in turn are food for various bird species, whilst other birds such as the siskin (Carduelis spinus) feed on the seeds in autumn.