The Vegetation of Magnesian Limestone Cliffs at Markland Grips Near Sheffield

Abstract

Outstanding characteristics of the Magnesian Limestone outcrop to the east of Sheffield are the 'grips', deep valleys with vertical cliff-like sides, believed by geologists to have arisen by collapse of the roofs of subterranean stream-channels. At Markland Grips, about 12 miles south-east of Sheffield near Clowne (Derbyshire) there are two such valleys joining just below that length of the right-hand valley which was chosen for detailed study (Fig. 1). Attention was focused chiefly on the vegetation of the cliff and of the scree at its foot. The plateau between the two valleys was planted or semi-natural woodland before it was felled during the war of 1914-18, since when most of it has been left to regenerate naturally. It is now covered with secondary woodland of Betula and Fraxinus with some Acer pseudo-platanus, Ulmus glabra, Quercus robur, Taxus baccata, Sorbus aucuparia and Ilex aquifolium, and with locally dense scrub and undergrowth of Cornus sanguinea, Crataegus monogyna, Ligustrum vulgare, Rubus fruticosus and Rosa spp. The oldest trees are between 20 and 30 ft. in height and there are numerous young plants of Fraxinus, Betula, Sorbus aucuparia and Quercus. No detailed examination was made of the vegetation of the plateau, but many calcicolous herbs, including Viola hirta, Poterium sanguisorba and Origanum vulgare were noticed along the sides of the marginal ride. The cliff top. Between the marginal ride and the edge of the cliff is a narrow strip whose vegetation appears to be more natural than that of the plateau. The dominance of ash and birch is here less complete, while oak, elm and yew are more abundant and the trees have attained greater dimensions than on the plateau (Table 5), birches being found up to 49 ft. high with girths at breast height up to 42 in. Occasional trees of Tilia platyphylios are found. Tree regeneration is proceeding actively and it is interesting that saplings of Fraxinus are more abundant than those of Betula, reversing the order of abundance of the larger trees (Tables 2 and 3). It seems likely that Fraxinus may ultimately replace Betula as the community approaches maturity.