W1 - Salix Cinerea-Galium Palustre woodland

Summary

Synonymy

Salix carr Willis & Jefferies 1959 p.p.; Salix cinerea carr Wheeler 1980c p.p.; Woodland plot type 32 Bunce 1982; Scutellaria galericulata-Alnus glutinosa Association Birse 1982 p.p.

Constant species

Salix cinerea, Galium palustre.

Rare species

Lysimachia thyrsiflora.

Physiognomy

The Salix cinerea-Galium palustre woodland has a canopy dominated by 5. cinerea but stands vary considerably in their overall appearance. Where invasion is more recent, there can be a confused mass of bushes of varying height and density but older stands have a more even look with usually a single tier of sallows forming a canopy 4—8 m high. Here, there can be an abundance of standing dead wood beneath, where thickly-set colonising bushes have been shaded out by the developing survivors, but long-established sallows, especially multistemmed individuals which form broadly-spreading crowns, usually cast a light shade.

The commonest woody associate, though it is still no more than occasional, is Betula pubescens and scattered trees of this species, together with scarcer Alnus glutinosa, Quercus robur and Betula pendula, sometimes break the sallow canopy, reaching 10-15 m. Other Salices are uncommon (there are sometimes records for the osiers, S. viminalis and 5. purpurea) but there can be scattered bushes of Crataegus monogyna, Corylus avellana and Frangula alnus. Saplings of Betula pubescens, Quercus robur and Alnus occur very occasionally.

The field layer varies in its cover and composition but the general appearance is of an open scatter of herbs with different species attaining occasional local prominence. Quite commonly there are mosaics developed in relation to canopy gaps and over undulations of wetter and drier ground. The commonest species throughout is Galium palustre but Mentha aquatica and Juncus effusus are also frequent, the latter sometimes forming large tussocks in lighter shade. Then, there are scattered plants of Angelica sylvestris, Ly copus europaeus, Ranunculusflammula, R. repens, Epilobiumpalustre, Equisetum fluviatile, Filipendula ulmaria, Cirsium palustre and Rumex sanguineus. Less common, though sometimes abundant, are Caltha palustris, Hydrocotyle vulgaris, Potentilla palustris and Iris pseudacorus and, in North Yorkshire and central Scotland, the national rarity Lysimachia thyrsiflora occurs (e.g. Birse 1982). In some stands, there may be much Rubus fruticosus agg.