What’s Douglas Fer?

Is Douglas-fir a pine, a spruce, a hemlock, or a true fir? The answer is: None of the above. Douglas-fir was given its own genus – Pseudotsuga – more than a century ago. That’s Latin for "false hemlock." The oft-overlooked hyphen in Douglas-fir is meant to signify that Douglas-fir is not a "fir" at all.

Now that you've learned that interesting tidbit, read on for other facts about Oregon's State Tree.

Douglas-fir trees grow nearly 250 feet tall, can have a trunk diameter of nearly 10 feet, and tends to produce a long branch-free trunk. Those qualities make it perfect candidate for logging. Although characterized as a softwood, lumber from Douglas-fir is remarkable strong, stiff, and durable. It is used extensively for pilings, railway ties, window and door frames, cabinets, tank vats, and the manufacture of plywood. Douglas-fir are not only magnificent members of the biosphere, they have long been Big Business in North America and Asia.

Several recent articles report great news about our future and that of the Douglas-fir.

One team of scientists grew Douglas-fir seedlings in sunlit chambers with either ambient atmospheric CO2 concentrations near 400 ppm or CO2 levels near 600 ppm. In addition, some of the chambers were at ambient temperature and others were maintained at ambient temperature plus 4°C.

Detailed measurements of the seedlings were made over an 18-month period beginning 32 months after the CO2 and temperature treatments were initiated. Light-response curves were measured and used to calculate the light-saturated rate of photosynthesis. Elevated CO2 coupled with the higher temperatures significantly increased the light-saturated rate of photosynthesis. And temperature proved to be more important than did CO2.

Lewis et al. suggested that a future of higher temperatures and elevated CO2 "May substantially increase carbon uptake rates in Douglas-fir, assuming other environmental factors do not limit photosynthesis."

In a related effort, some of these same team members reported on a study where Douglas-fir seedlings were grown in sunlit controlled-environment chambers with ambient and ambient plus 179 ppm CO2, and ambient and ambient plus 3.5°C temperature. Among many other findings, the five-year-old seedlings' needle fresh mass increased between 5 and 10 percent due to elevated CO2.

Ormrod et al. also concluded that "This research indicates that needles of Douglas-fir seedlings in a warmer future environment may be enriched in light-harvesting and energy-dissipating pigments." Whether or not this yields greater biomass will require research in a mature forest, but the lesson from these experiments on Douglas-fir seedlings is certainly promising. Both studies add to a new wave of published research suggesting that many types of trees will substantially increase their carbon sequestration in a world of higher CO2 levels and potentially higher temperatures.

We know that the rate of CO2 buildup in the atmosphere has slowed in recent decades. It seems likely that the biosphere is largely responsible for the observed trend.

Even under the most optimistic scenarios, adoption of the Kyoto Protocol has a very small impact on the buildup of atmospheric CO2. As we learn more about various trees, we find that their ability to uptake and hold carbon could dwarf the projected impacts of Kyoto. When it comes to impacting the future atmospheric CO2 levels, the Big Money ought to be on Big Trees, not Big Government.

Lewis, J.D., Olszyk, D., and Tingey, D.T. 1999. Seasonal patterns of photosynthetic light response in Douglas-fir seedlings subjected to elevated atmospheric CO2 and temperature, Tree Physiology, 19, 243-252

Ormrod, D.P., Lesser, V.M., Olszyk, D.M., and Tingey, D.T. 1999. Elevated temperature and carbon dioxide affect chlorophylls and carotenoids in Douglas-fir seedlings, International Journal of Plant Sciences, 160, 529-534.