Slowed tree growth threatens Oregon timber industry


Though not as immediately devastating as wildfires, slowed growth rates nonetheless pose a grave threat to Western Oregon’s commercial timber operations, experts say.

Rising soil temperature and falling soil moisture from prolonged drought are reducing the growth rate of certain tree species by as much as 2% per year, eventually leading to stagnation and death, said Henry Lee, a research statistician at the U.S. Environmental Protection Agency.

“These declines are happening throughout western Oregon. If you think western Oregon is wet and trees are healthy, they’re not,” Lee said at Oregon State University’s Feb. 26-27 “Forest Health in Oregon” seminar in Corvallis, Ore.

While 2% may not sound like a lot, the compounding effect over time means that affected trees will stop growing entirely within 50 years — a trend that’s strongly associated with tree mortality, Lee said.

“This is just going to continue,” he said. “This is the path we’re on.”

Hemlock trees at lower elevations are the most profoundly affected by drought, with core samples of their heartwood indicating that growth rates have been slowing since the late 1970s, Lee said.