Douglas fir (DF)

Pseudotsuga menziesii

Native range

Native to the western parts of North America with a wide natural range. Only the ‘green’ Douglas fir from the coastal part of the range is suitable in Britain.

Provenance choice

Provenances from coastal Washington are recommended for western and more oceanic parts of Britain, while material from the south Washington Cascades can be used on suitable soils in drier zones of eastern Britain.

Site requirements

This is a high yielding early successional species of intermediate shade tolerance which produces a high quality timber. It is best suited to areas of high humidity with 750-2000 mm of rainfall but it can also cope with summer droughts. It is cold hardy but suffers from exposure and therefore is suited to more sheltered areas such as lower to middle valley sides. It is damaged by late spring frosts and young trees can be prone to toppling. It grows well on mineral soils of poor to medium fertility but requires adequate moisture and good soil aeration. It will not grow well on waterlogged or calcareous sites, or in competition with heather. It can be grown in mixture with larch or with Sitka spruce.

Pests and pathogens

Douglas fir is usually considered moderately resistant to Heterobasidion (Fomes root and butt rot) as it suffers from little decay, but it is susceptible to root rot and therefore may become unstable as a result of attack by Heterobasidion. It is also affected by the fungal disease Swiss needle cast, Phaeocryptopus gaeumannii, which is widespread but relatively insignificant although climate change predictions (warmer, wetter springs) may increase the incidence. Both mature and young trees can also be susceptible to infection by Phytophthora ramorum, although only when grown in close proximity to other infected plants which are a major source of spores.

Use

A warming climate is likely to result in greater use of Douglas fir, provided that the sites are not too exposed and have adequate soil moisture.