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Knowing Nature . . .

February 3, 2006
Jocie Ingram

Female Douglas-fir Cone photo © Dave Ingram

Towering trees are one of the most impressive features of Vancouver Island. A visit here wouldn’t be complete without stopping to see some old growth giants. One of the biggest trees in BC is the Douglas-fir. The largest Douglas-fir in the province, near Port Renfrew, is 4 metres wide and 89 metres high. It is estimated to be nearly 1000 years old.

The scientific name for Douglas-fir is Pseudostsuga menzisii. “Pseudostsuga” means “false hemlock”, and the species name “menzisii” was named after Archibald Menzies (1754-1842). Menzies, a Scottish surgeon and botanist, was the first to collect Douglas-fir while exploring BC’s coast in the late 1700’s with Captain Vancouver. The common name for the tree commemorates David Douglas (1799-1834), another famous Scottish botanist.

Douglas, financed by the Horticultural Society of London, sailed around the horn to Fort Vancouver (near Portland), arriving in 1825. Douglas, driven to collect plants and seeds and send them to England, explored thousands of miles of BC’s coast and interior. He traveled with a small terrier, and preferred to live off the land and sleep without a tent. Douglas met with many challenges, and nearly died when his canoe capsized between Prince George and Quesnel.

Douglas died a violent death at age 35 when he fell into a pit with a wild bull while collecting plants in Hawaii. Whether the death was accidental, or a murder remains a mystery. Douglas introduced 254 plants to England, including Douglas-fir, and sent approximately 7000 plant species to Kew Gardens. A Douglas-fir that he planted in England remains there today.

Douglas-fir is characterized by soft (not prickly) yellowish green to dark green needles, with bluntly pointed tips. Bark is brown-grey and is smooth with resin blisters when young. Mature firs have very thick bark with deep fissures, which gives the tree some resistance to fire.

Male Douglas-fir Pollen Cones photo © Dave Ingram

Male pollen cones are 6-10 mm long and are yellow to reddish. Female seed cones (6-10 cm long) are green when young turning reddish-brown when they mature in late summer. The cones have many scales, and distinctive 3-pronged bracts extend beyond the scales. The trident-like bract is diagnostic for Douglas-fir, and some liken it to the tiny hind legs and tail of a mouse.

Douglas-fir is not a “true” fir. True firs have cones that are upright, and scales (with seeds) that are shed directly from the tree. The denuded “core” of the cone remains attached to the tree. In contrast, Douglas-fir cones droop from branches, and when mature the entire cone falls to the ground.

Near the end of March, the male pollen cones of Douglas-fir start to let off quantities of pollen. The pollen, dispersed by wind, finds its way to a female cone, which is at this stage green and sticky. The pollen grains fertilize the ovules of the female cone, which are located at the base each cone scale. Conifers, unlike flowering plants, have ovules that are “naked” and not encased by an ovary. For this reason, conifers are classified as Gymnosperms, which is Greek for “naked seed.”

The Conifers, or trees that retain their leaves (needles) year round, thrive in our temperate climate that has wet, mild winters and dry summers. Conifers haven’t always been here, but they have been around for 7000 years. 18 000 years ago, the climate started to get warmer, precipitating the end of the ice age. Slowly the ice melted, and soil gradually formed from the barren rocky landscape. Eventually, trees were able to colonize the area.

There is only one species of Douglas-fir in BC, but it is divided into to two varieties, a coastal and interior form. Interior Douglas-fir (Pseudotsuga menzisii var glauca) does not grow to the same girth and height as its coastal relative. It also has smaller cones, and the needles often have a bluish cast. The interior form extends east to the Rocky Mountains, and is scattered south along western mountains all the way to Mexico. The coastal form ranges from the south coast of BC to northern California.

Most of Vancouver Island is in the Western Hemlock biogeoclimatic zone. Douglas-fir, which prefers good light conditions, readily colonizes an area after it has been cleared or burned. But, on most of Vancouver Island, Western Hemlock will eventually succeed Douglas-fir, and is therefore the “climax” species.
The Coastal Douglas-fir zone, where Douglas-fir is the climax tree, is very restricted in BC. It only exists along a narrow strip of coastal southeastern Vancouver Island, and areas in the adjacent mainland. The Douglas-fir zone is characterized by a drier, Mediterranean-like climate.

Douglas-fir is one of the most economically important trees in BC, a tree that literally “built” our province. Beginning in the late 19th century, easily accessible lowland stands of Douglas-fir were harvested for their superior quality timber. Today, only 1% of coastal old growth Douglas-fir remains.

An old growth Douglas-fir is one of the most impressive, and awe-inspiring trees in the world. Animals such as Red Squirrels depend on conifer cones as a winter food source. Many insects, birds and mammals rely on Douglas-fir and other conifers for food and shelter. Since only 1% of coastal old growth Douglas-fir remains, it would be wise to protect this magnificent tree for all to behold.