Faster Koa Tree Growth Without Adverse Ecosystem Effects (image) USDA Forest Service - Pacific Southwest Research Station Share Print E-Mail Caption Janis Haraguchi, an Institute of Pacific Islands Forestry biologist, measures the diameter of an Acacia koa tree. Haraguchi and other US Forest Service scientists found the stem diameter of koa trees with timber potential doubled through a combination of treatments that included thinning, herbicides and fertilizers. Credit U.S. Forest Service Usage Restrictions None Share Print E-Mail 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.