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You’ll find black alder throughout most of Europe, from Scandinavia to the Mediterranean countries and eastward into the Caucasus and Ural Mountains. It normally grows below elevations of 1 000 m, although it occurs along watercourses up to 1 800 m in the mountains of central Europe. Alders are adapted to a wide range of temperatures, but require a fair amount of water to thrive. As their roots are well adapted to very wet soils, alders grow primarily on marshy waterlogged sites, on riverbanks and lake shores and on plateaus with high soil-moisture content.
At 10 to 25 m tall (and exceptionally 35-40 m), black alder is a relatively small tree species. It’s also short-lived for a tree, with individuals normally reaching 60 years, but can reach 160 years in some areas. Its dark green leaves are 4 to 10 cm long, and have a characteristic inward notch at the end. Flowers are clustered in grouped catkins that become visible in the autumn and mature in the following spring. The fruits are small woody cones, resembling small pine cones. They turn from green to dark-black in autumn, and remain hanging from the branches throughout winter. Wind helps the pollination, but the seeds spread mainly on water, protected by an oily water-resistant outer coat and a corky structure that helps them float.
The wood of the black alder is soft and porous, but durable if kept under water. It is used for jetties and underwater supports, bridge piles and small boats. It is fast-growing when young and can also be coppiced, providing material suitable for biomass production and high quality charcoal. This alder is a valuable pioneer species that is useful in land reclamation, flood control, the stabilisation of riverbanks and the functioning of river ecosystems. The black alder can improve soil fertility because its roots are able to fix nitrogen thanks to a symbiosis with the bacterium Frankia alni.
Learn more about the research the European Commission does on forests and forestry.