WL5A Picea sitchensis forest
Vegetation
This is a forest community dominated by a dense canopy of Picea sitchensis (mean canopy height = 13.9 m, n = 68). Other tree species are typically absent, although occasionally one might find some suppressed growth of Ilex aquifolium. Due to the heavy canopy and dense needle layer, the field layer is very poor; Hedera helix is a constant here whilst Dryopteris dilatata and Rubus fruticosus agg. are frequent, but cover of these species is typically dismal. Rarely, where the canopy has opened up, bramble can be abundant. Occasionally, there are some clumps of Blechnum spicant, some grassy cover provided by Agrostis capillaris, Agrostis stolonifera or Holcus lanatus, or some heathland elements in the form of Potentilla erecta or Galium saxatile. The main bryophytes are Kindbergia praelonga, Thuidium tamariscinum and Lophocolea bidentata, frequently accompanied by Hypnum jutlandicum, Brachythecium rutabulum or the pale threads of Plagiothecium undulatum, but again these usually are not abundant.
Ecology
These are commercial forestry stands that are commonly planted in marginal areas in the uplands (mean slope = 8.0°, n = 68; mean altitude = 204 m, n = 68). The soils, mainly podzols, gleys and peats, are typically acidic and of low fertility and are drained prior to afforestation (mean organic content = 32.3%, n = 68). Included here are mainly closed-maturing and mature stands in which a dense needle layer is likely to develop.
Sub-communities
No sub-communities have been described for this community.
Similar communities
Due to the dominance of Picea sitchensis, mature stands of this type are unlikely to cause confusion. Where first rotation Sitka spruce stands are still at a pre-thicket or thicket stage they may be best regarded as transitional between the present community and the previous vegetation, which is likely to be a type of wet grassland, heathland or bog.
Conservation value
These plantations are dominated by non-native species and are typically perceived as having a low conservation value. They are fairly species-poor overall but with a reasonable bryophyte flora (total species/100 m2 = 22.0, n = 68; bryophyte species/100 m2 = 10.7, n = 68).
Management
Sitka spruce stands are managed for timber production. They are typically thinned and pruned when the trees are between 15 and 22 years old. Thinning continues every few years until felling between the age of 35 and 45.