W3 - Salix Pentandra-Carex Rostrata Woodland

Summary

Synonymy

Alder wood Rankin 1911 b; Open carr Pearsall 1918; Closed carr Pearsall 1918 p.p.; Salix carr Ingram et al. 1959; Fen carr Proctor 1974; Willow carr Adam et al. 1975 p.p.; Crepido-Salicetum pentandr ae Wheeler 1980c; Sphagno-Salicetum atrocinereae Birse 1984 p.p.

Constant species

Salix cinerea, S. pentandra, Angelica sylvestris, Cardamine pratensis, Carex rostrata, Caltha palustris, Filipendula ulmaria, Galium palustre, Geum rivale, Valeriana dioica, Calliergon cuspidatum, Mnium hornum, Rhizomnium punctatum.

Rare species

Salix nigricans, Carex appropinquata, Carex diandra, Corallorhiza trifida, Lysimachia thyrsiflora, Pyrola rotundifolia.

Physiognomy

The Salix pentandra-Carex rostrata woodland is a very distinctive woodland type, fairly constant in its overall composition and structure and with clear northern European affinities in its flora. The canopy is always low, though often uneven-topped and invariably dominated by bushy Salices, most commonly Salixpentandra and/or S. cinerea. Although the former Northern Montane willow can be found occasionally in other kinds of wet woodland in northern Britain, only in this community does it make more than a local contribution to the canopy. When it is abundant here, its typical spreading habit, with branches reaching down to the ground and often re-rooting, gives stands a very characteristic appearance. Mature individuals of S. cinerea can open up with age, too, so that, even where the cover of bushes of these species is dense, the canopy can be somewhat open. Other Salices are rare, though they can be locally abundant. Most distinctive among these are two other Northern Montane species, S. nigricans and S. phyli-cifolia which, when they occur together, frequently hybridise to produce a perplexing range of intermediates (S. × tetrapla'. Meikle 1975) among which the identity of the parents can be lost (e.g. Proctor 1974, Adam et al. 1975, Lock & Rodwell 1981). S. aurita also occurs in some stands and, more rarely, the osiers S. viminalis and S’, purpurea and these, too, may hybridise among one another and with the other Salices.

The only other woody species to occur with any frequency in the community is Betula pubescens and even this is only occasional. Alnus glutinosa is rare and the associates of the canopy of southern fen woods like Frangula alnus, Rhamnus catharticus and Viburnum opulus are typically absent. Neither does an underscrub of Rubi or Ribes spp. ever play a prominent part here.