Forest thinning treatments (IMAGE) University of California - Berkeley Caption Using machines to manually remove small trees and underbrush poses fewer risks than prescribed burns, but often comes at a much higher cost. Credit UC Regents photo by Evett Kilmartin Usage Restrictions with credit License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.