Lowland dry acid grassland occurs on nutrient-poor, free-draining soils overlying acid rocks or sands & gravels (superficial deposits). It can also form over calcareous parent material where leaching has resulted in the development of nutrient-poor conditions (NIEA, 2005).
- Site: Occurs as small patches of matrix of other grassland types
- Soil: Acidic soils
- Main species: Calcifuge plants
- UK: 25,000 ha
- NI: 674 ha
- Lowland dry acid grassland typically grows on acidic soils of pH 4-5.5
- Characteristic vegetation includes grasses & herbs that grow on lime-deficient soils, derived from acid rocks such as sandstone, acid igneous rocks or sands & gravels.
- The NIEA Habitat Action Plan (2005) defines lowland dry acid grassland as a species-rich habitat, with calcifuge (cannot grow in alkaline soil) plant species & less than 25% cover of scrub of dwarf shrub. Such habitats may also include both enclosed & unenclosed acid grassland usually below 300 metres that is managed within enclosed field units (UK Biodiversity Steering Group, 1998).
- Lowland dry acid grassland is similar to U4 Festuca ovina – Agrostis capillaries – Galium saxatile grassland in the NVC of Great Britain.
- Lowland dry acid grasslands tend to occur as small patches of a matrix of other types of grassland.
- In Northern Ireland lowland dry acid grassland is often a species-poor derived of former heathland (NIEA, 2005). It is often a part of a mosaic with grasslands similar to CG10 Festuca ovina – Agrostis capillaris – Thymus praecox grassland, calcicolous, or base-rich grassland & occasionally MG5 Cynosurus cristatus – Centaurea nigra neutral grassland
- Characteristic plant species include heath bedstraw Galium saxatile, sheep’s fescue Festuca ovina, common bent Agrostis capillaris, sheep’s sorrel Rumex acetosella, pill sedge Carex pilulifera & tormentil Potentilla erecta.
- Heather & bilberry may occur in low abundance
- Common bryophyte species include Rhytidiadelphus squarrosus & Pleurozium schreberi.
Current Status in UK & Northern Ireland
- Agricultural intensification & forestry are primarily responsible for the decline of lowland dry acid grassland in Britain & Ireland over the past century (NIEA, 2005). An estimated 25,000 ha remain in the UK (Burke & Critchley, 2000) but precise data is unavailable.
- Lowland dry acid grassland is fragmented & no large areas of lowland dry acid grassland exist in NI (NIEA, 2005). They are scattered & occur as a small component of habitat mosaics, with ‘lowland heathland, ‘lowland meadow’ & ‘maritime cliff & slopes’ (NIEA, 2005).
- The NICS (1992) estimated just over 1000ha was ‘hill pasture’ within lowland land classes which equates closely to lowland dry acid grassland.
- The NICS (2000) estimated that the area of ‘hill pasture’ declined by 26% within a 7 year period (1991-1998). Lowland dry acid grassland is therefore estimated to cover 674 ha (<0.1% of NI land area)
- The NICS (2007) showed that the area of Acid Grassland (as a whole) declined by 13% between 1990 & 2007. Acid Grassland covers 1.6million ha (approx. 6.5% of land area in UK).
- Lowland dry acid grassland is threatened by over-grazing, abandonment, habitat fragmentation, afforestation, air pollution, climate change, pressure from recreation, industrial & urban development.
- Glenarm Wood
- Grangemore [Bann Estuary ]