For the purposes of this exercise, swamps are defined as lowland areas that are waterlogged for most of the year and dominated by stands of tall grasses, such as common reed (Phragmites australis) or reed canary grass (Phalaris arundinacea). Left unmanaged, swamp can be be encroached by woody scrub, typically by species of willow (Salix spp.) but also by alder (Alnus glutinosa) or birch (Betua spp.).

Swamp habitats are found mainly in waterlogged situations on level or gently sloping ground at watersides, in ditches, and typically in mosaics with other wetland habitats, e.g fens, mires and pools.