Silver Birch is abundant on Mousehold Heath, forming areas of attractive woodland. The upright boles and bark of birch trees catch the light and create interesting views in any season. A relative, the Downy Birch, also lives on the Heath and has peeling, papery-looking bark.
Birch is described as a pioneer tree because its wind-blown, winged seeds can quickly colonise bare ground. They can thrive in poor, sandy soils, and also in cold temperatures: birch has been an inhabitant of Norfolk since the last Ice Age.
Birch began spreading on Mousehold from the later 19th century onwards after grazing and mineral extraction had ceased. Gradually, tracts of open heathland began to be replaced by birch scrub and later woodland. Good heathland management sometimes means having to cut it back.
Birch trees have small leaves which do not create deep shade, so other plants such as Bracken, Bramble and Wood Sage can form an understorey as well as more shade-tolerant trees such as Holly and Yew.
Birch woods support an interesting variety of wildlife. All the following species have been recorded on Mousehold.
Some insect species such as the impressive Birch Sawfly are adapted to living on birch. Their larvae look like pale green caterpillars and can be found feeding on leaves in Summer.
[Image courtesy Will Stewart]
Hoof fungus forms brackets on dead or dying birch trunks. Its fibrous, brown flesh was once used as tinder.
Fruiting bodies of the Fly Agaric toadstool make a scarlet, toxic display among leaf litter in Autumn.
Grey Dagger moth caterpillars feed on birch trees. The adult moth is often well camouflaged against the white bark.
[Image courtesy Magnefl, CC BY-SA 4.0 license via Wikimedia Commons]
Patches of custard-coloured, slimey froth are likely to be the Dog’s Vomit slime mould. These colonies of primitive, plasmodial organisms have the ability to move slowly around in search of food.
Silver Birch produces abundant pollen, which you can see floating on the surface of ponds and puddles in Spring.
The pollen grains in this picture are magnified 400 times.
[Image courtesy Dr Steve Boreham].
All images courtesy the author, unless otherwise indicated.
