Floodplain woodland is the common term used to describe woods dominated by alder Alnus glutinosa and willow Salix spp. on floodplains. The full official name given to this habitat type in the EC Habitats Directive is Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae). You may also see the term 'residual alluvial forests' which was formerly used to refer to floodplain woodland of this type.

These woods develop on floodplains in a range of situations from islands in river channels to low-lying wetlands alongside the channels. They typically occur on base-rich, eutrophic soils subject to periodic inundation. In other words, on fertile lowlands by rivers, which flood occasionally.

Most floodplain woodlands are dynamic, being part of a successional series of habitats. Their structure and function is best maintained within a larger unit that includes the open communities, mainly fen and swamp, of earlier successional stages.

In other situations, alder woods occur as a stable component within transitions to surrounding dry-ground forest. These transitions from wet to drier woodland and from open to more closed communities, provide an important facet of ecological variation.

Trees growing along riverbanks are excluded from this habitat type, except where they form part of a wider network of alluvial woodland and wetland communities.

Clearance of riverine woodland has eliminated most true alluvial forests in the United Kingdom. Many surviving fragments, as elsewhere in Europe, are fragmentary and often of recent origin.