Grazing for restoration on Magnesian limestone cliff top grassland

Trials by English Nature, the statutory body for promoting conservation in England, have tested grazing regimes under its 'Wildlife Enhancement Scheme' on Magnesian Limestone grassland, including coastal cliffs in County Durham. It was found that stocking rates of 1-2 cattle or 4-10 sheep per ha were effective in restoring short grassland, 0.5 - 1.0 cattle or 2-5 sheep per ha are required for their maintenance. In this regime grazing is restricted from mid-June to November, allowing grassland plants to flower and set seed. These regimes help to refine those indicative stock densities identified by (Mitchley & Malloch 1991)

The situation in the north east also points to another important conclusion when considering the conservation of butterflies. In northeast England a sub-species of northern brown argus (Aricia artaxerxes), the 'Durham' or 'Castle Eden' argus (Aricia artaxerxes salmacis) thrives on Magnesian Limestone grasslands along the coast. Unlike the large blue butterfly, which not only has a special association with an individual ant species and requires short-cropped grassland (<3cm, optimal 1cm) the Durham argus needs an intermediate, 6-10cm turf, for its survival. For this species there is no specific association proved with ants and winter grazing is the preferred management. Heavy spring and summer grazing can cause population crashes (Ellis 1997).

References

Ellis, S. 1997. The Northern brown argus in North-east England. British Wildlife, 9/1., 22-27.

Mitchley, J. & Malloch, J.C. 1991. Sea Cliff Management Handbook for Great Britain. University of Lancaster & Joint Nature Conservation Committee, Peterborough.