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The Red Alder's (Latin name Alnus Rubra) natural habitat stretches from Alaska to California in a band that is 70 km wide along the coast. This tree is a pioneer species that will quickly colonise open ground. The tree is not a long lived species, surviving until about 70 years of age, although it can live up to 100 years. The tree starts flowering at about the age of 4 years.
(Agroforestry Research Trust, 1999.)
The same tree produces both male and female catkins, separately, on the previous year's growth. About 2000 seeds are produced which are normally spread by the wind but also by the water and birds. The seeds have a viability of about 45%. Seeds are normally dispersed between the months of October and March.
The Red Alder has a fibrous root system that develops nodules in which the bacteria Frackia resides in a symbiotic relationship with the tree. The nodules fix nitrogen from the atmosphere producing about 150 kg of nitrogen per hectare per year that is available to the soil. This is achieved when the trees are about ten years old with a stand of about 600 tree per hectare. The tree does not like exposed, nutritionally poor, badly drained and frost prone sites. It requires full sun in order to survive and grow. The tree is very much a green manure species ensuring those other plants in the area will have sufficient nitrogen.
The Red Alder can increase soil organic matter by up to 20% and is a primary storage medium for soil nitrogen. Organic matter also improves soil structure, drainage, mineral content and aeration.
When planting, care should be taken to keep the roots moist as the modules, when dried out, will die. The seedlings, when about 3" high, are ready for planting out between November and March. Care should be taken in handling the brittle seedlings. The tree is hardy to minus 30C. Growth will be about 1 meter per year for about 18 years under favourable conditions. Natural regeneration will take place provided there is full sunlight and exposed soil. Young stumps at least 6" high will sprout new shoots; however chances of the tree sprouting new shoots will reduce on each occasion that it is coppiced. Very little affects the Red Alder in the way of desease or insects. Logs from Red Alder may be inoculated with mushroom spoors to provide a useful harvest.
Native Americans used the bark as a purgative and for dressing wounds. The bark contains salicin that is related to asprin. The sap is edible and may be tapped between mid February and the first week of April. The sap can be made into vinegar and crystalline sugar. Check with your doctor before using it.
The wood from the Red Alder is very popular for its uniform color and the ability to stain easily. It is the most significant commercial species of hardwood in the American North West. The grain is fine and regular, warps little, is not very dense and has one of the lowest shrinkage rates of all hardwoods. The wood is not durable when bared to the elements. It dries fast and well.
The timber is used for firewood, woodchips, veneer and pallets. Higher grade timber is used in the manufacture of furniture. The wood is also durable in water and is used in river piles. The wood is also for smoking meat and fish and is an alternative fertilizer when dug into the soil, breaking down quickly and improving the soil texture.
Twigs, leaves and the sawdust from the tree can be used as a supplement for cattle and rabbits. The roots and stems can be used in basketry. The wood, prepared in boiling water, can provide red, brown and orange dye's by boiling in water. Also the wood burns evenly and produces good quality charcoal.
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