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Tree of the month....The Alder


sean
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As the title suggests this thread is intended to focus on one tree a month. It will hopefully be a celebration of our Native Trees in order to aid us all in learning as much as possible about them.

 

Our experiences working with them, fungal associations, pests and diseases, photographs, myths, legends and their place in the arts and culture. As said before a celebration and learning resource.

 

I thought we could use the Celtic Tree Ogham calendar as a starter whose origins lie with the Celtic tribes who migrated to Britain around 700 – 500bc. Trees were venerated by the ancients for their many gifts which were a mainstay of peoples lifestyles. Everybody was born under a particular tree (the same as our own zodiac sign).

Hopefully this thread will work and we can collate all sorts of useful and interesting information about our native trees. I hope there are a few of you who feel the same.

 

This months tree covering the dates 18th March to 14th April is The Alder (Alnus Glutinosa)

 

Please feel free to add to previous Months.....Birch and Ash

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Alder is monoecious, so each tree bears both male and female flowers. Male catkins are dark yellow-brown in colour, and are up to 5 cm. long when they are fully open. At 6 mm. in length, the female flowers are much smaller in size, and are red, erect and cone-like in shape. The flowers appear before the new leaves, in March (or early April in the Highlands), and pollination is by the wind. Pollinated female flowers grow into ovoid fruits about 1.5 cm. in length, which are green in colour and grow in clusters of up to 4 at the end of twigs. These ripen and turn woody by October, and release a number of small flat red-brown seeds, each weighing about 0.004 gm. The seeds have small 'wings', which are air-filled membranes that enable them to float on water, and dispersal is by both wind and water. Seeds have been recorded as germinating on the surface of water, and then rooting successfully when they are washed up on land. The empty cones can persist on the tree until the following spring and are a distinctive feature of the alder tree in winter.

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Alder is particularly noted for its important symbiotic relationship with a bacterium (Frankia alni), which forms nodules on the tree's roots. This nitrogen-fixing bacterium absorbs nitrogen from the air and makes it available to the tree, with the rate of fixation estimated at up to 125 kg. of nitrogen per hectare per year. Alder, in turn, provides the bacterium with carbon, which it produces through photosynthesis. As a result of this mutually-beneficial relationship, alder improves the fertility of the soils where it grows, and as a pioneer species, it helps provide additional nutrients for the successional species which follow.

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A few more notes to add...

Alders prevent erosion along the banks of rivers, particularly those flowing through soft rock or prone to torrential flow, and they have been widely planted for this purpose in the Highlands of Scotland.

 

The foliage is highly palatable to invertebrates, having 141 phytophagous species associated with it, including the alder kitten moth (Furcula bicuspis).

 

Alder timber is very resilient to decay under water and, like elm and pine, it has been used for water pipers and for piles under bridges and houses; much of Venice is built on alder piles. It is still used for sluice-gates and other structures along water courses.

 

It was also traditionally the best wood for making clogs, partly because it is a poor conductor of heat; most surviving alder coppices were formerly the haunt of 'cloggers'.

 

The catkins and bark give an inferior black colouring known in medievil times as 'poor man's dye'.

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