Douglas-fir is the tree I know best. When I was growing up, I lived in a forest of these trees. The texture of their bark, the shape of their needles and cones, and the scent of their foliage are all, to me, familiar and somehow reassuring. I remember individual Douglas-firs that I have known just as I remember people. The most common wild trees around here, they’ve shaped both my internal and external landscapes.
Douglas-firs (Pseudotsuga menziesii) are not firs (genus Abies), although they have in the past been classified as firs, as well as pines, spruces, and hemlocks (Pseudotsuga means “false hemlock”). The genus Pseudotsuga includes two species in western North America as well as several others in eastern Asia, hinting at an ancestral relationship that connects these two continents. Douglas-fir arrived in my province of British Columbia as the climate warmed after the last Ice Age, around 10,000 years ago. Today, Douglas-firs are among Canada’s largest conifers; the largest coastal trees can be over 100 metres tall and 5 metres in diameter, and can live for over 1000 years (of course, not all reach quite these sizes), while in the drier, colder interior, the trees are smaller and usually live for less than 400 years.
Douglas-fir is intimately connected with the presence of fire. These trees colonize sites after forest fire and other disturbances, and the thick bark of mature trees protects them from low-intensity fires. The fire in turn clears out the underbrush and younger competing trees, leaving the mature trees standing and alive. On the coast, where major fires are not common, stands of ancient Douglas-firs may mark the site of forest fires from centuries ago. In the dry interior, fires occur often and forests here are shaped and defined by fire. Pure open-canopy stands of Douglas-fir reflect an environment where fire is a regular occurrence. I remember seeing Douglas-firs in the forest near my old home whose trunks were still blackened by a decades-old fire.
Douglas-fir forests in British Columbia are relatively warm and dry, and they’re an essential habitat for many plants and animals. Many small mammals and birds eat Douglas-fir seeds. Woodpeckers forage for insects that live in the thick, furrowed bark, and excavate nests in the wood of dead and dying trees. Deer, elk, and bighorn sheep find shelter and food in the Douglas-fir forests in winter, when other food sources may be buried below the snow. Coastal Douglas-fir ecosystems in particular are home to many rare plant species and several endangered animal species, but these regions today consist of only a small fraction of their former extent. Douglas-fir has long been a desirable tree in the logging industry because of its strong, durable wood, and people love living in the mild climates of Douglas-fir ecosystems. Over the years, we have cut trees to make space for agricultural fields and built cities where forests once stood. Most of the large Douglas-fir trees that once grew on the coast are now gone.
Douglas-fir is named for David Douglas (1799-1834), a Scottish botanist and explorer. Douglas was a collector for the Horticultural Society of London, and over his lifetime introduced 7000 new species of plants to England. He reached the Pacific Northwest in 1824 and has left his name throughout this region’s taxonomic landscape, including Douglas maple, Crataegus douglasii (black hawthorn), Douglas aster, and many others. Known as the “Grass Man” among native people for his knowledge of plants, he died in Hawaii at the age of thirty-five. And while David Douglas lent his name to Douglas-fir’s common name, the tree’s scientific name (P. menziesii) remembers another Scot, Archibald Menzies (1754-1842), a physician and naturalist on Captain George Vancouver’s expedition to the Pacific Northwest in the late eighteenth century. Menzies was the first to describe and collect specimens of Douglas-fir.
I wonder what those men and others like them must have felt when they first arrived here to a landscape of seemingly endless forests and massive trees. It is a landscape that is now lost to us, although thankfully a few trees still remain as memories of what the land has lost – and what it may be again one day. I cannot know what Douglas or Menzies thought of the trees, or what the native peoples – who had such a different way of living with the land than we do today – thought of them. But for myself, I know that the Douglas-fir simply means home.
If you would like to read more about the biology and ecology of Douglas-firs, I highly recommend the book Tree: A Life Story, by David Suzuki and Wayne Grady, which chronicles the life of a single Douglas-fir tree.