Global warming may spur increased growth in Pacific Northwe...(to start with. According to Greg La...)

According to Greg Latta, an OSU faculty research assistant and principal investigator on the study, most of the climate scenarios that were used showed increases in temperatures from one to eight degrees but precipitation projections were all over the map, sometimes up and sometimes down. At lower elevations, tree growth is constrained when moisture is limited and drought stress is an issue.

"The lower-elevation forests are getting warmer just like those at higher elevations, but in most scenarios the precipitation doesn't increase enough there to offset that," Latta said. "The cumulative effect could be declines in forest growth of 1 to 3 percent a year in low-elevation Oregon forests, which could have a substantial long-term impact if trees are being managed for timber harvest."

Among the findings of the study:

• Any climate scenario that shows an increase in future temperatures could potentially lead to an overall increase in forest productivity in the Pacific Northwest, especially in Washington.

• Increases in high-elevation forest productivity were partially offset by probable declines in lower-elevation forest productivity.

• Private timber lands that have accounted for 83 percent of the timber harvest in this region over the past decade are concentrated at lower elevations.

• The models showed that increases in forest growth at higher elevations could increase carbon sequestration for those areas, but they did not include potential changes in fire frequency and severity, which are also affected by biomass accumulation.

• Other possible changes not reflected in the productivity projections were disturbance regimes such as diseases and insect outbreaks that are also affected by climate.

• The combination of tree mortality and declining future growth on private timberlands could lead to concerns about lower harvest levels and reduced carbon s
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