Alnus glutinosa (Alder)
Other Names: Common Alder, Black Alder, European Alder, Aller
Description: This medium sized tree is common on wet ground, near rivers, ditches and lakes and can be known to invade open wet habitats. The tree is easily spotted in winter as it has a distinct purplish hue and holds small cones which can be seen from a distance. Has attractive male and female catkins which can be seen in winter and blunt, rounded leaves. The tree is roughly conical in shape.
Uses: Alder wood is very good at resisting rot, so long as it is kept wet. Traditionally this made it very useful for sluice gates, boats and even water pipes. In modern times Alder is mainly used for pulp and plywood. Alder coppices well and is often cut to make charcoal.
Conservation Value: Alder leaves are a food source for the caterpillars of several species of moth including the Alder Kitten, the Autumnal and the Pebble hook-tip. The Catkins, showing early in the year, provide a much-needed nectar source for bees and the seeds are eaten by several birds including the Goldfinch and Siskin. Alder woodlands provide excellent conditions for several species of moss and lichens and the roots of the Alder are well knows as ideal locations for Otter holts.
Preferred Locations: Another tolerant being able to cope with clay, sand, chalk or loam soils but certainly prefers damp and poorly drained locations and riparian habitats.
Size: Generally not exceeding 12m with only 4-6m wide canopy spread.
Time to reach full height: 10 to 20 years.
Lifespan: 60 years.
Betula Pendula (Silver Birch)
Other Names: Birch Tree, Common Birch, Lady Birch, European White Birch, Weeping Birch
Description: A common, graceful, fast growing deciduous tree with silvery white bark and slender ascending branches. Lower trunk bark is often deeply fissured on mature trees and quite dark and the trunk often develops dark diamond shaped marks in the bark. Twigs at the end of branches often droop down, giving the tree a weeping aspect and are covered in masses of swinging catkins in early spring. The tree is often found in clusters or can be the dominant species for a whole wood.
Uses: Birch wood is hard and tough which makes it ideal for making furniture, handles for tools and toys but is of little commercial value in the UK as the trees do not grow a large as they do elsewhere. However, the Birch is an excellent wood for burning and is in high demand for log burning stoves. The bark is also sometimes used for tanning leather.
Conservation Value: As the canopy of birch trees is very thin, allowing lots of light to pass through, birch woods provide a perfect habitat for some rarer species such as English Bluebell, Wood Anemone, Wood Sorrel and Violets to grow. The tree provides habitat for over 300 different insect species which in turn provide food for many predator species. This in turn creates a strong food chain and makes the Silver Birch a vital conservation tree. Birch woodlands are also associated with many types of fungi including Birch Milk Cap, Birch Brittlegill and the Birch Knight. Their abundant seeds are eaten by a wide range of bird species.
Preferred Locations: Chalk, clay, sand and loam soils but with a tendance toward light acidic soils and often colonises heaths and moors.
Size: Up to 30m tall, but often between 12m and 20m. Has a canopy spread of between 6m - 8m.
Time to reach full height: 20 to 50 years.
Lifespan: 90 years.