Trees in Southeastern US (IMAGE) Georgia Institute of Technology Caption Trees in the Southeastern United States emit higher levels of isoprene as they are placed under stress from dry conditions. Isoprene is a precursor for the formation of ozone in the atmosphere. This forest is shown near Atlanta, Georgia. Credit Credit: John Toon, Georgia Tech 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.