I was impressed with the dense growth of straight trees and tried a drive-by shot. Hybrid poplar trees are an alternative crop for Oregon agriculture. A hybrid poplar averages 10 feet of growth in the first year under good conditions. They reach harvest size (12 inch girth) in about 1/3 of the time it takes a Douglas fir. Many of these farms are owned by paper companies. For harvest they cut the entire tree down and grind all of it into pulp for paper production.
If interested see: http://oregonprogress.oregonstate.edu/springsummer-2000/ready-set-grow.