Northwest forestland owners are expected to modify the type of seedlings they use to replant properties after logging to cope with higher temperatures, experts say.
Timber producers are already looking beyond the traditional “seed zones” for their current climate and will likely even shift to species other than the regional staple Douglas fir over time, experts say.
“Trees that are adapted to that area may no longer have that climate to grow in,” said Jeff Debell, geneticist with the Washington State Department of Natural Resources.
The goal remains to match trees to the climate for which they’re best suited, though with an eye for changing conditions over their decades-long life cycle, DeBell said.
“It’s really a risk question,” he said.
Landowners who plant trees geared toward seed zones in which they currently thrive may run the risk of having those species grow poorly as they approach harvest age, he said.
However, they also want to avoid planting trees that may thrive in potential higher temperatures if that means they won’t be adapted to the region earlier in their life cycle, DeBell said.
“If you do it too quickly, you could have the same problem as if you weren’t paying attention to climate change,” he said.
Timber producers who want to anticipate the future without being too aggressive may want to choose seedlings adapted to only slightly warmer conditions, DeBell said.
“If you have to hedge your bets a little bit, get your seeds from somewhat warmer and drier rather than much warmer and drier,” he said.
To help landowners make such decisions, Oregon State University and the U.S. Forest Service have developed a “seedlot selection tool” that allows them to run different climate scenarios for various locations.
Research is also taking place to validate how trees are performing over time as a way of “truthing” those models, DeBell said.
Apart from tree growth, landowners also have to consider whether the timber will be salable in several decades when it’s logged, said Richard Zabel, executive director of the Western Forestry and Conservation Association.
“The problem is Doug fir is such a valuable commodity tree, it’s tough for them to give it up,” Zabel said.
Some landowners are trying to reduce risk by planting multiple species in addition to Douglas fir, such as alders and pines, he said.
“They’re making incremental changes.”
Large timber producers often no longer own mills, so they’re making decisions about tree species on separate tracks, he said.
Sawmills don’t have to look out as far ahead as landowners, as they adapt their log inventories to customer demands, Zabel said.
However, the modern “head rigs” that measure logs and adjust blades to maximize production of desirable lumber are flexible and can cope with variability in species, he said.
“The new ones are really expensive but they’re pretty adaptable now,” Zabel said.
Market considerations can only carry so much weight in planting decisions, since the trees must still be healthy enough to generate salable logs, said David Lewis, an applied economics professor at OSU’s College of Agricultural Sciences.
“Even if something’s worth more on the market, if it doesn’t grow well, you still can’t produce it,” Lewis said.
Lewis has co-authored a study that modeled changes in West Coast tree species on private lands, based on changes in climate through the year 2100.
“The most consistent change is the reduction in Douglas fir,” he said.
Even accounting for the high value of the species, the study concluded that landowners will shift planting to hardwoods and Ponderosa pines, Lewis said.
In Oregon and Washington, about half the harvested forestland is currently replanted with Douglas fir, but that’s expected to fall to one-fourth by the century’s end, he said.
“There will still be Douglas fir, but there will be less of it,” Lewis said.
The model was based on current planting decisions made in warmer areas and applying those to areas where temperatures are expected to rise.
Aside from its effects on forestland economics, the change in tree species is also expected to impact the region’s environment, Lewis said.
“You will have transitions in wildlife habitat that harms some species and benefits other species,” he said.