Researchers (IMAGE) University of Nebraska-Lincoln Caption University of Nebraska-Lincoln researchers (from left) Caleb Roberts, Craig Allen and Dirac Twidwell, have found evidence that multiple ecosystems in the U.S. Great Plains have moved substantially northward during the past 50 years. Credit Craig Chandler/University Communication/University of Nebraska-Lincoln Usage Restrictions None 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.