Further Results of Excluding Sheep from High-Level Grasslands in the North Pennines

Abstract

(1) Long-term botanical studies on the effects of preventing sheep from grazing grasslands dominated by Agrostis-Festuca, Festuca, Nardus and Juncus squarrosus have been carried out on the Moor House National Nature Reserve. The sites ranged in altitude from 545 to 830 m O.D. (2) The heterogeneity of these grasslands is stressed, and the interpretation of the results obtained from relatively small fenced areas is confined to generalities. (3) Previous findings (after 8 yr of protection) of a decline in species-number is confirmed (after 24 yr of protection), but there are indications that the grasslands are in no way stable, and compositional changes are still occurring. (4) After 24 yr protection the more acidic, species-poor Festuca grasslands have become dominated by Deschampsiaflexuosa and have a bright green appearance. Carex bigelowii has increased to cover large areas of these grasslands and Festuca ovina, earlier suppressed by D. flexuosa, shows signs of recovering. The dense mat of slowly decaying vegetation has shown signs of instability and of being torn from the surface by harsh winter storms. Vaccinium heath is likely to develop on suitable areas. (5) The more species-rich Agrostis-Festuca grasslands have developed distinctive patterns of vegetation, with patches dominated by Deschampsia cespitosa, Holcus mollis, Alchemilla glabra, Rumex acetosa, Galium boreale, G. verum and Urtica dioica. These communities are expected to spread. (6) The Juncus squarrosus grassland, at the lower altitudinal range, became dominated by Eriophorum vaginatum (Juncus squarrosus was eliminated), and the vegetation is expected to revert to Calluna-Eriophorum bog. On the other hand, the Nardus grassland altered little and there are no indications of future dramatic changes in composition. (7) That no shrubs or trees have appeared is most likely due to the small size of the protected areas; seedlings have been found elsewhere on the Reserve. (8) Changes in the structure of the grasslands were considerable, and were shown to improve conditions for the invertebrate fauna. Standing crops were larger, but the consequences on the distribution of nutrients were unclear.