Eastern hemlock trees (IMAGE) University of Maryland Caption Eastern hemlock trees in the study area. Changes in the abundance of beech and hemlock are responsible for much of the woody biomass stored in Midwestern forests over the last 10,000 years. Credit David Mladenoff Usage Restrictions Credit must be given to the creator. No derivatives or adaptations of the work are permitted. License CC BY-ND 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.