Lowland forest is associated with rivers and is characterized by periodic flooding and water-logged soils. The soils are silty and easily erodible. Common trees include ash, silver maple, box elder and black willow. Elm used to be an important species until Dutch Elm disease wiped out the older trees in the late 1970s. Notice how many of the trees have multiple trunks; this is most often a result of damage by ice and other debris during spring flooding. Approximately 12% of the Cannon River Wilderness Area is lowland forest.