|Scientific name||Erica tetralix – Andromeda polifolia bog|
|Common name||Cross-leaved Heath – Bog-rosemary bog|
Download full pdf synopsis: BG2B
This bog community usually exhibits typical hummock/hollow microtopography. It has a number of constant species but typically the most abundant vascular plant species are the dwarf shrubs Calluna vulgaris and Erica tetralix. Also, usually prominent are the sedges Eriophorum angustifolium, Eriophorum vaginatum, Trichophorum cespitosum/germanicum and Rhynchospora alba, together with Narthecium ossifragum. The bryophyte layer is abundant and composed chiefly of Sphagnum capillifolium, Sphagnum papillosum, Sphagnum tenellum and Hypnum jutlandicum. Also frequently occurring are conspicuous white patches of Cladonia portentosa, rosettes of Drosera rotundifolia and stems of Andromeda polifolia. Searching amongst the Sphagnum, one often finds strands of Odontoschisma sphagni. The suite of less frequent species is mostly composed of other bryophytes (e.g. Sphagnum subnitens, Sphagnum cuspidatum, Sphagnum magellanicum, Sphagnum austinii, Sphagnum beothuk/fuscum and Leucobryum glaucum) and other lichens.
This is primarily a community of raised bogs but occasionally of blanket bog, usually in the lowlands. It occurs on deep, acidic, ombrogenous and oligotrophic peats.
No formal sub-communities have been described for this community. However, on western raised bogs Andromeda polifolia would be scarcer than in the midlands, while Carex panicea, Campylopus atrovirens and Pleurozia purpurea would be more abundant.
From the other main raised bog community, BG2A Eriophorum vaginatum – Vaccinium oxycoccos bog, the present community differs in having a lower frequency and abundance of Vaccinium oxycoccos, Aulacomnium palustre and Sphagnum recurvum agg. as well as much more frequently having a component of Trichophorum cespitosum/germanicum and/or Rhynchospora alba. Other communities of lowland blanket bog, e.g. BG2D Erica tetralix – Schoenus nigricans bog, typically have Schoenus nigricans.
Most of the examples of this community qualify as EU HD Annex I habitat 7120 Raised bog (active)*. However, also included here are some instances of vegetation from habitat 7130 Blanket bog (active)*. Some vegetation may technically qualify as 7120 Degraded raised bog. This is on average a moderately species-poor community but supports several specialists.
The main threat to the raised bogs supporting this vegetation is turf-cutting, either by hand or machine, and associated drainage. Some sites have also suffered from afforestation. Locally, action has been taken to address these impacts and some sites are managed strictly for conservation.