Restoration Ecology Project (IMAGE) University of Washington Caption University of Washington students work with students, parents and teachers from a local elementary school restoring an area around storm water retention ponds at the school. To discourage Himalayan blackberries and other invasive species from growing back, cardboard is an inexpensive and effective barrier. Credit University of Washington 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.