H11 - Calluna Vulgaris-Carex Arenaria Heath

Summary

Synonymy

Dune heath auct. angl., Calluna-Erica cinerea heath Gimingham 19646, 1972 p.p.; Calluna-Empetrum nigrum heath Gimingham 19646, 1972 p.p.

Constant species

Calluna vulgaris, Carex arenaria.

Rare species

Euphorbia portlandica, Trifolium suffocatum, Usnea flammea.

Physiognomy

Calluna vulgaris is the only constant sub-shrub throughout the Calluna-Carex arenaria heath, and it is often present in abundance, sometimes as an overwhelming dominant in rather impoverished vegetation. Generally, though, the cover of heather is discontinuous, decidedly patchy in younger or grazed stands, and there is frequently some other sub-shrub present, either intimately mixed with the Calluna or with the bushes of the codominants forming a more distinct mosaic. The most characteristic of these associaties is Erica cinerea, with Empetrum nigrum ssp. nigrum figuring in some places, and each of these can be abundant, locally to the exclusion of Calluna itself. Very occasionally, Ulex gallii can be found and in some stands Rosa pimpinellifolia is plentiful, with Erica tetralix and Salix repens occurring in transitions to wetter heath. Vaccinium myrtillus is typically very rare.

Even when some of these other sub-shrubs are present, the community can be distinguished from similar assemblages by the constancy of Carex arenaria, though this is hardly ever more than moderately abundant and often distinctly senile, except where the sand substrate becomes locally mobile, when renewed vigour and cover in the plant usually presage a transition to patches of Carex dune vegetation. Ammophila arenaria is also frequent through the community, though it is characteristically sparse and usually decidedly moribund, with just scattered shoots.

In more species-poor stands, little else than these plants may be represented, but other tracts of this kind of heath show considerable enrichment. First, among grasses, there is often some Festuca rubra or F. ovina (inadequately distinguished in the available data), with Agrostis capillaris and Anthoxanthum odoratum also occurring frequently in some situations and, less commonly, Poa pratensis (probably P. subcaerulea). The annuals Air a praecox and, more sparsely, A. caryophyllea can sometimes be found too. Apart from C. arenaria, sedges are absent though Luzula campestris occurs quite often.