CG7 - Festuca Ovina-Hieracium Pilosella-Thymus Praecox/Pulegioides Grass Land

Summary

Synonymy

Herbland Tansley & Adamson 1925; Primitive Chalk grassland Tansley & Adamson 1925 p.p.; Rabbitgrazed Chalk grassland Tansley & Adamson 1925 p.p.; Breckland Grasslands A and B Watt 1940; Old ex-arable grassland Cornish 1954; Hornungia petraea stands Ratcliffe 1959 p.p.; Annual community Ratcliffe 1961 p.p; Pulpit Hill Field vegetation Lloyd 1964; Catapodium rigidum stands Clark 1974 p.p.; Festuca ovina|Hieracium pilosella|Cladonia spp. lichen-rich grassland Wells et al. 1976; Ant-hill vegetation King 1977a p.p.; Breckland grasslands Ratcliffe 1977 p.p.; Helictotrichon pratense-Koeleria cristata-Phleum phleoides grassland Smith 1980; Lichen grasslands Smith 1980 p.p.

Constant species

Festuca ovina, Hieracium pilosella, Leontodon hispidus, Thymus praecox!pulegioides, Hypnum cupressiforme.

Rare species

Artemisia campestris, Astragalus danicus, Carex ericetorum, Galium parisiense, Himantoglossum hircinum, Hornungia petraea, Medicago lupulina ssp. minima, M. sativa ssp. falcata, M. x varia, Minuartia hybrida, Phleum phleoides, Potentilla tabernaemontani, Silene conica, S. otites, Thymus serpyllum, Veronica spicata, V. verna, Pleurochaeta squarrosa, Bacidia muscorum, Buellia epigaea, Diploschistes scruposus var. bryophilus, Fulgensia fulgens, Lecidea decipiens, Squamaria lentigera, Toximia caerulea var. nigricans, T. lobulata.

Physiognomy

The swards of the Festuca-Hieracium-Thymus grassland can be open or closed but, even where there is a continuous cover of vegetation, this usually lacks the dense, plush quality of the Festuca-Avenula swards. Festuca ovina (only on rare occasions replaced by F. rubra) is constant and frequently abundant, but it generally occurs as small isolated tussocks or an open network of somewhat attenuated, procumbent shoots. Koeleria macrantha is the only other grass that is at all common throughout, other important Mesobromion species being markedly patchy or scarce. Avenula pratensis, for example, is frequent only in certain subcommunities and, even then, may be sparse in heavilygrazed swards. Dactylis glomerata and Briza media, two other major Festuca-Avenula grasses, are here strikingly uncommon.

In general, it is herbaceous dicotyledons, and especially chamaephytes and therophytes, which give the vegetation its distinctive character. Among the former, Hieracium pilosella is usually the most frequent and abundant: more than 1000 rosettes m-2 have been recorded in this kind of vegetation (e.g. Bishop et al. 1978). Thymus praecox is also constant and it, too, can be locally prominent. T. pulegioides, though inadequately distinguished from T. praecox in the bulk of the data, is very characteristic of this community (Pigott 1955).