Bob Zybach, an experienced forester with a PhD in environmental science, warned Oregon's government decades ago that unchecked growth in forests would result in catastrophic wildfires. Changes in forest management policies under Bill Clinton's administration that reduced logging to protect old growth trees and the spotted owl is the major cause of worsening wildfires. Experts agree that a century of fire suppression has caused forests to become overgrown and filled with dead wood and debris that easily ignites in dry summer heat.  American Indians formerly used large controlled fires to prime the land for grazing and hunting.