|Scientific name||Betula pubescens – Agrostis capillaris woodland|
|Common name||Downy Birch – Common Bent woodland|
Download full pdf synopsis: WL4B
Betula pubescens dominates the low canopy of this woodland community, usually accompanied by Sorbus aucuparia. The understorey is composed of Ilex aquifolium and Corylus avellana whilst other tree species are rare. The field layer has a distinctly grassy character as Agrostis capillaris and Anthoxanthum odoratum are amongst the constants and both Agrostis canina/vinealis and Holcus lanatus are frequent. Other field layer constants include Galium saxatile and Potentilla erecta (both characteristic of the upland grasslands of group GL4), Oxalis acetosella, Blechnum spicant and Rubus fruticosus agg. The bryophyte layer is typically dominated by Thuidium tamariscinum accompanied by Polytrichum formosum, Isothecium myosuroides, Rhytidiadelphus loreus, Mnium hornum and Dicranum scoparium.
This is a successional woodland community of humid, acidic podzols and well-drained mineral soils. It typically occurs on fairly steep slopes in uplands and, given the grassland indicators present in the field layer, in areas where the grazing levels of deer or livestock are high. Soils are infertile.
Two sub-communities have been described for this community. The Ilex aquifolium – Plagiochila spinulosa sub-community (WL4Bi) is a more oceanic variant with a richer bryophyte flora, the presence of filmy ferns (Hymenophyllum spp.) and a high frequency of both Ilex and Sorbus. The Rubus fruticosus – Salix cinerea sub-community (WL4Bii) lacks these indicators while Holcus lanatus and the titular species are more frequent.
The abundance of grass species is a good indicator for separating these stands from the other birch communities. Furthermore, these woods are far more diverse in plant species than any others in group WL4. They are related to, probably successional to, the acidophilous oakwoods of group WL1 but oaks are seldom found in the present community.
This is on average a very species-rich woodland community with an exceptionally diverse bryophyte flora. Greater diversity occurs in sub-community WL4Bi.
These sites typically have high levels of grazing so natural regeneration of tree species can be impaired. Locally, woods have been fenced and deer culling employed to try to address this. Other threats are woodland clearance and invasion by non-native species such as Rhododendron ponticum. Spraying with herbicide, cutting, and removal of seedlings have been used to combat the spread of this species within these woods.