'Mangroves' of the North (IMAGE) University of Washington Caption The researchers nicknamed boreal floodplains "mangroves of the North" because there are almost impenetrable tangles of willow trees and roots in places and cyanobacteria are fixing nitrogen like their counterparts in tropical and subtropical mangroves. Credit T DeLuca/U of Washington Usage Restrictions Credit required 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.