A tree ally in the recovery of 'difficult' land
PUBLISHED: 08:46 22 November 2017
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Nature: Grace Corne looks at the uses of alder.
Some years ago we planted a row of alder trees on the edge of a little stream bordering a marsh. They have been most successful. These trees need to be near water and if conditions are right they will grow rapidly. Unfortunately, they also produce numerous seedlings which can ‘take over’ and which need attention every year. Nevertheless alders are ideal trees for the bank of a stream because their roots help to bind the soil and give the bank stability.
Alder roots are useful in other ways for they are hosts to nitrogen-fixing bacteria. Initially this may cause concern because the roots appear to have some disease as the bacteria occur in rather unpleasant looking swellings on them. However those nitrogen-fixing properties may be very valuable for those wishing to reclaim ‘difficult’ land.
Alder leaves fall quite late in the autumn and become very dark in colour before falling. When the leaf fall occurs the old cones remaining on the twigs become very noticeable. Next year’s flowers will already have formed and will be wind-pollinated in the spring.
Alder trees tend to be quite small and rarely make ‘big logs.’ However the wood is very useful as it becomes harder in water and is ideal for strengthening river edges. The wood is also an attractive pinkish colour and is favoured by wood turners. Alder wood has another and perhaps more unexpected use which is in the production of gunpowder. In earlier days the bases of the clogs worn by factory workers were made from shaped alder wood.
It is said that alder trees are not actually native but they arrived in Britain seven and a half thousand years ago. The trees have a reputation for ‘bleeding’ if they are cut and this stems from the fact there is so much tannin in the bark it does actually leak out.
Those researching alder and elder trees should be extra careful if they live in the London area. The names ‘alder’ and ‘elder’ sound very similar when spoken there and confusion was discovered when elder trees were also reported as ‘bleeding’ which they certainly do not.