M16 - Erica Tetralix-Sphagnum Compactum Wet Heath Ericetum Tetralicis Schwickerath 1933

Summary

Synonymy

Molinietum caeruleae Rankin 1911b, Tansley 1939 p.p.; Molinia consocies Summerhayes & Williams 1926; Submoorland heath Muir & Fraser 1940 p.p.; Gentiana pneumonanthe localities Simmonds 1946; Damp heath Rose 1953; Wet heath Rose 1953, Rutter 1955, Newbould 1960, Ivimey-Cook & Proctor 1967; Three-species heath Williams & Lambert 1959; Calluna-Erica tetralix wet heath Gimingham 1964 p.p., Bannister 1966 p.p.; Ericetum tetralicis boreoatlanticum Ivimey-Cook et al. 1975; Campylopo-Ericetum tetralicis Birse & Robertson 1976 p.p.; Mire noda 1-5 Daniels 1978 p.p.; Narthecio-Ericetum tetralicis Moore (1964) 1968 sensu Birse 1980 p.p.

Constant species

Calluna vulgaris, Erica tetralix, Molinia caerulea, Sphagnum compactum.

Rare species

Erica ciliaris, Gentiana pneumonanthe, Lepidotis inundata, Rhynchospora fusca.

Physiognomy

The Ericetum tetralicis is characteristically dominated by mixtures of Erica tetralix, Calluna vulgaris and Molinia caerulea, but the proportions of these are very variable, being influenced by differences in the water regime and trophic state of the soils, and also by grazing and burning, the last factor being able to transform the appearance of particular stands over short periods of time and producing great structural diversity within a small compass (e.g. Williams & Lambert 1961). E. tetralix often grows very vigorously here, typically on these wetter soils adopting a semi-prostrate habit (Bannister 1966). Calluna, on the other hand, is often subordinate and of somewhat weak growth (Gimingham 1972), though it can become abundant in drier stands or where there has been deliberate encouragement by controlled burning. In other situations, Molinia is very much the dominant, with the ericoids reduced to sparsely-scattered bushes among dense tussocks of the grass, such that some accounts of the community have grouped it within a broadly-defined Molinietum (Rankin 1911b, Summerhayes & Williams 1926, Tansley 1939).

Typically, however, no other sub-shrubs attain high frequency through the community as a whole, though some can be of local importance. Thus, Erica cinerea and Ulex gallii figure occasionally, and sometimes with local abundance, in transitions to drier heaths in southwest England, and E. cinerea and U. minor can occur in similar situations further east. More strikingly, around Poole Harbour and in Cornwall, the Ericetum provides one of the loci for the nationally-rare E. ciliaris and its hybrids with E. tetralix ( = E. × watsonii Benth.: Chapman 1975).