Floodplains are the broad, flat, low-lying areas at the bottom of river valleys.
They are the land areas that typically flood when the river or stream flows over its banks, usually in the spring when the snow melts, or during periods of unseasonably high rainfall.
Floodwaters typically scour the surface of the floodplain and deposit silt and sediment as they subside. A permanent cover of trees is important on floodplains to help stabilize banks and prevent excessive erosion.
Most tree species are unable to survive frequent flooding, but a few species specialize in this habitat type, particularly cottonwood (Populus deltoides), silver maple (Acer saccharinum), box elder (Acer negundo), and black willow (Salix nigra). These are all tall trees with extensive, shallow root systems that hold the soil tightly.