... 1960s and 1970s, the growth and abundance of submerged plants inFIGURE 7. 14 A beaver impoundment in Virginia. Beaver-created wetlands often have stand-ing dead trees, members of the pre-flooding ... phase. Four wetland community types exist on all of the lobes: freshwater wetlands (includ-ing both marshes and swamps), and intermediate, brackish, and salt marshes. The domi-nance of one ... communities, to floating-leaved and emergent communities, to a sedgemeadow, and eventually to a shrub and forest community (van der Valk and Bliss 1971).The trees and shrubs were wetland species, such...