Lowland Dry Acid BNG Units
High
Grassland
Trusted by Developers and Landowners
What is Lowland Dry Acid Grassland?
Lowland dry acid grassland occurs on nutrient-poor, acidic soils, often sandy or gravelly. It supports a mix of fine grasses, mosses, lichens and small rosette forming herbs such as sheep’s sorrel, bird’s foot trefoil and mouse ear hawkweed. Grazing and light disturbance maintain the open mosaic structure that supports its characteristic species diversity.
Why It Matters for BNG
Creating or restoring acid grassland provides high value biodiversity units and strengthens heathland and grassland networks. It suits sites with acidic sandy or gravelly soils.
Maintaining low nutrient soils, grazing and scrub control enables landowners to generate BNG units from this scarce habitat with modest management changes.
Where You'll Find It
Lowland Dry Acid Grassland habitat typically occurs on nutrient-poor, free-draining soils with a pH between 4 and 5.5 and supports a characteristic range of grasses, herbs, lichens, and mosses. It is usually managed as a pasture. mainly in the warm, dry lowlands of southern England, including Breckland, the Suffolk Sandlings, the New Forest and Dorset and Wealden heaths.
Soil and Site Requirements
Lowland dry acid grassland forms on acidic soils with a pH of 4.0 to 5.5. Substrates are nutrient poor, free draining sands, gravels or acid rocks with shallow topsoils. Phosphorus and nitrogen levels must remain low. Compacted, heavily limed or fertilised soils are unsuitable.
How New Lowland Dry Acid Grassland Is Created
Inputs
• Allow natural colonisation where adjacent acid grassland is present
• Sow pioneer or nurse grass mixtures at appropriate rates
• Introduce green hay from local donor sites to supply seed
• Maintain low soil nutrients and control invasive perennial weeds
Management
• Apply managed grazing to maintain open structure
• Use controlled disturbance to support germination and diversity
• Avoid heavy machinery that damages fragile soils
Landscape
• Restore grassland close to existing acid grassland or heathland mosaics
• Use local green hay to retain local character
• Position creation where long term grazing management can be secured
How Existing Lowland Dry Acid Grassland Is Improved
Inputs
• Control scrub, bracken and invasive species
• Reinstate grazing where it has lapsed
• Remove nutrient enrichment where feasible
Management
• Manage grazing to maintain the open, species rich sward
• Adjust timing and intensity to retain diversity
• Monitor species richness and respond to declines
• Avoid neglect or overgrazing, both of which reduce condition
Landscape
• Restore adjacent land to strengthen grassland and heathland networks
• Break up encroaching scrub to reopen habitat structure
• Improve ecological connectivity across lowland heaths and acid grassland mosaics
Target Condition
Lowland dry acid grassland in its defined BNG condition should:
• Support high species richness, up to 25 species per square metre
• Maintain low nutrient status with no dominance by coarse grasses or weeds
• Show an open, fine grass structure with mosses, lichens and small herb species
• Demonstrate continuity of grazing or disturbance regimes
• Avoid scrub encroachment or nutrient enrichment that reduces diversity
The BNG Value of Lowland Dry Acid Grassland
• Distinctiveness: High to Moderate
• Condition Potential: High, where management supports species richness
• Habitat Connectivity: Strengthens grassland and heathland mosaics and supports specialist invertebrates
• Climate and Landscape Context: Improves resilience in lowland heath and grassland systems and contributes to long term ecological networks
Species Typical of Lowland Dry Acid Grasslands
Canopy or Primary Layer
• Sheep’s fescue (Festuca ovina)
• Common bent (Agrostis capillaris)
• Wavy hair grass (Avenella flexuosa)
Shrub or Secondary Layer
• Heather (Calluna vulgaris)
• Bracken (Pteridium aquilinum)
• Gorse species, where encroaching
Ground Flora or Understorey
• Sheep’s sorrel (Rumex acetosella)
• Mouse ear hawkweed (Hieracium pilosella)
• Bird’s foot trefoil (Lotus corniculatus)
• Heath bedstraw (Galium saxatile)
• Mosses
• Lichens
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Frequently Asked Questions
What is Lowland Dry Acid Grassland?
A priority habitat found on well-drained, nutrient-poor, acidic soils (low pH), characterized by fine-leaved grasses (like fescues) and dwarf shrubs (like heathers).
How is BNG measured here?
Condition is assessed by the dominance of key indicator species (e.g., Wavy Hair-grass, Sheep's Fescue) and the presence of non-native/aggressive species.
How can I achieve BNG?
Enhancement through low-intensity grazing, management to reduce scrub/tree encroachment, or removal of nutrient-rich topsoil to expose underlying acidic substrate.
What is the BNG target condition?
A Good condition is defined by a high abundance of acid grassland species, an open sward structure, and a low cover of invasive/dominant species.
What management is required?
Grazing (often with sheep or cattle) is the key management tool. Cutting and removing cuttings can also be used to maintain the nutrient-poor conditions required by the habitat.
Exploring Other Habitats?
Arable Field Margins Pollen and Nectar
Arable field margins pollen and nectar are grass margins around arable fields sown with wildflowers and legumes managed specifically to provide pollen and nectar resources for invertebrates. The mix must include at least four nectar-rich flowering species and the margin is kept low-input and rotationally cut to maintain flowering through the season. The arable field must remain in a crop rotation including an arable crop.
Unlike wild bird seed margins, the management objective here is flowering continuity for pollinators rather than seed retention for birds. This habitat type sits within the Cropland broad habitat in the BNG metric and is classified separately from tussocky margins, cultivated margins and game bird mix.
Arable Field Margins Game Bird Mix
Arable field margins game bird mix are margins, strips, blocks or corners around arable fields sown with wild bird cover crops and left unharvested over winter so that seed produced by the plants remains available to farmland wildlife. The arable field must be in a crop rotation that includes an arable crop, such as wheat, barley, maize or oats, even if in certain years the field is in temporary grass, set-aside or fallow.
Mixes typically combine seed-bearing cereals, brassicas and oil-rich crops to provide food through the winter hungry gap and standing cover for gamebirds and declining farmland bird species.
Arable Field Margins Cultivated Annually
Arable field margins cultivated annually are strips along the edges of arable fields, typically 2–12 metres wide, managed under a low-input regime to support annual arable plants. They are lightly cultivated each year, usually in late summer or autumn, without herbicide or fertiliser, creating the open, disturbed soil conditions that annual arable flora requires to germinate.
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