British NVC community W6

NVC community W6 is one of the woodland communities in the British National Vegetation Classification system, characterised by a canopy of willow and alder with a field layer of tall herbs on an enriched alluvial soil. It can be a form of primary woodland in lowland river floodplains, and is one of seven woodland communities in the NVC classed as wet woodlands. It was once very common but is now generally scarce and fragmented.

Description

W6 Alnus glutinosa-Urtica dioica woodland is a broad term to cover several types of wet woodland, wherever they occur on nutrient-rich soils. It is most typical of the floodplains of lowland rivers, but can also be found on partly-drained peatlands, including both fens (which are calcareous) and mires (acid). It is found throughout the lowlands of England, Wales and southern Scotland. The characteristic (constant) tree species are alder and various species of willow. If black poplar is a native tree in Britain, this would be the habitat in which it grows, but it is not apparent that there are any truly wild populations, as there are very few female trees and no signs of regeneration, even in East Anglia where it has been claimed as a native. Other species of poplar, especially hybrid black poplars are sometimes cultivated in river floodplains, and these plantations are also a type of W6 woodland.

The habitat is generally a seasonally-flooded landscape in which trees can only become established if they are tolerant of waterlogging (mainly alder and willow) or have a dry foothold.