Poplar and Willows (image) University of Washington Share Print E-Mail Caption In this study site along the Snoqualmie River, poplar and willow are the dominant plant species in this nitrogen-limited, cobble-dominated floodplain. Photos were taken in 2002, 2006 and 2015. Credit Sharon L. Doty Usage Restrictions Photo credit required. Share Print E-Mail 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.