Common (or black) alder (CAR)

Native range

Native to all parts of the British Isles and mainland Europe.

Provenance choice

Little known about provenance differences so seed from good quality British stands should be preferred.

Site requirements

A light demanding pioneer species characteristic of wet areas, stream sides and riparian zones.  Cold hardy and frost resistant, but not tolerant of exposure. Requires sites with a high, though not stagnant, water table, with a medium to rich nutrient supply, and pH values above 5. Grows best on deep loams and alluvial soils.

Pests and pathogens

Phytophthora alni is the most significant pathogen of black alder, causing mortality or chronic dieback.  The only other pathogens reported with any frequency include root rot fungi and some fungal foliar pathogens such as Melamsporidium, Taphrina and the shoot fungus Melanconium.

Use

Has a valuable role in soil improvement through fixation of atmospheric nitrogen and can be planted on reclamation sites for this reason. Likely to continue as an important tree species wherever the soil moisture requirements are met.

Common alder is categorised as a Principal tree species. These are species which are currently widely used for forestry and will continue to be a dominant unless affected by a new pest or disease or adversely affected by climate change.