Lowland Dry Acid Grassland
Lowland acid grasslands typically occur on nutrient-poor, generally free draining soils with pH ranging from 4 to 5.5 overlying acid rocks or superficial deposits such as sands and gravels. They often occur as an integral part of lowland heath, in parklands and on coastal cliffs and shingle. This habitat is largely restricted to land below 300 m. Acid grassland is usually characterised by a range of plant species such as heath bedstraw Galium saxatile, common bent Agrostis capillaris, sheep’s sorrel Rumex acetosella and tormentil Potentilla erecta. Acid grasslands can have a high cover of mosses and parched acid grasslands can be rich in lichens.
Like other lowland grasslands, lowland dry acid grassland has decreased to such an extent that it is now considered to be a highly threatened habitat. In a national context lowland acid grasslands are important for a range of rare and endangered bird, invertebrate and plant species, such as stone-curlew, nightjar, field cricket and Deptford pink Dianthus armeria. None of these nationally important species are actually found on the lowland acid grasslands of the North East but the habitat does support a number of plants that are regionally notable such as maiden pink Dianthus deltoides.
Lowland acid grassland underwent a substantial decline in the 20th century. There are currently thought to be 15 000 to 22 000 ha of lowland acid grassland in England, although comprehensive survey information is not available.
Within the North East, lowland acid grassland occurs in a mosaic with lowland heath at several sites on the coal measures. A few patches also survive in association with Magnesian Limestone grassland. However, the most distinctive and floristically diverse lowland acid grasslands in the region are found in association with outcrops of the Whin Sill. This is a quartz-dolerite intrusion than runs through the region from Teesdale up to the Northumberland coast. At lowland sites within Northumberland the outcrops support parched grasslands that contain a number of interesting and regionally notable plant species including maiden pink Dianthus deltoides (a species of which the Region holds nationally important populations), purple milk-vetch Astragalus danicus, and chives Allium schoenoprasum. In many respects these can be considered as northern outposts of southern acid grassland communities. A number of the most important sites are notified as SSSIs.
- Agricultural intensification by use of fertilizers, herbicides and pesticides, liming or re-seeding can destroy the interest of lowland acid grassland.
- Lack of management leading to rank overgrowth, bracken invasion, and the encroachment of scrub can lead to the loss of habitat.
- Overgrazing, sometimes associated with supplementary feeding, can cause damage.
- Development activities such as mineral and rock extraction, road building, housing and landfill are still leading to the loss of sites.
- Atmospheric pollution and climate change may affect lowland acid grasslands but this has not yet been fully assessed.
Opportunities for protection and enhancement
- Natural England makes payments through its Environmental Stewardship Scheme for the management of a number of Whin grassland sites within the Region.
- The Northumberland Whin Grassland Project, run by the Northumberland Wildlife Trust, is working to publicise the value of Whin Grasslands and to improve their management.