Colorado Tree Ring Sampling (IMAGE) Carnegie Institution for Science Caption Lee Anderegg collecting a tree core from a trembling aspen tree (Populus tremuloides) in the La Plata Mountains of Colorado as part of this study. Credit Photo is courtesy of Mike Anderegg. Usage Restrictions With credit 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.