testing vegitation (IMAGE) Penn State Caption Riparian buffer designs studied included widths of 35 to 100 feet, some all grass, some all trees, and some -- like the one shown -- both trees and grass. On some, the effects of harvesting grass every year and trees every three years were modeled. Credit Rob Brooks/Penn State Usage Restrictions non commercial use only License Licensed 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.