Shrubs Swamps are simply wetlands dominated by shrub species.
These wetlands are dominated by species like Red Osier Dogwood (Cornus stolonifera), Silky Dogwood (Cornus amomum), and shrub willow (Salix spp.) species. Like alder thickets in the north, Shrub Carr often replaces sedge meadows, wet meadows, low prairie, and calcareous fens in the south.
Alder thickets differ from shrub carrs in that they are dominated by Speckled Alder (Alnus rugosa). Speckled Alder is typically taller than those species found in shrub. This species also fixes nitrogen, which alters the nutrient levels and chemical cycles in the soil, affecting the other plants that grow in the understory. In the north, Speckled Alders often naturally invade and replace sedge meadow, particularly in the absence of fire.