Red alder (RAR)

Alnus rubra

Native range

Native to coastal areas of north west America from southern Alaska to California.

Provenance choice

It has been trialled on a wide range of sites in Britain and some provenance studies have been carried out. Preferred seed sources should be from good British stands or from coastal Washington or British Columbia.

Site requirements

A light demanding pioneer species which is suited to humid maritime environments and therefore is best suited to western and upland Britain. In its natural range it is often found in mixture with Douglas fir, Sitka spruce and other conifers. This is a pioneer and light demanding species which can grow very fast on suitable sites but is often quite short lived; it is cold hardy throughout Britain but is very vulnerable to spring and early autumn frosts. It is not tolerant of exposure. Best growth is found on soils of poor to medium nutrient regime and fresh to wet soil moisture. It is not suited to peat or alkaline soils and growth is limited on drier or nutritionally very poor soils.

Pests and pathogens

Has a low level of susceptibility to Phytophthora alni root and collar rot, compared with black alder.


The species could find an increasing niche as a component of conifer forests in western Britain.