Upland Mixed Ashwood BNG Units
High
Woodland and forest
Upland areas of northern and western England, particularly on base-rich soils
Trusted by Developers and Landowners
What is Upland Mixed Ashwood?
Upland mixed ashwoods are species-rich broadleaved woodlands found on base-rich soils in upland landscapes. They are typically dominated by ash, though locally oak, birch, wych elm, rowan, small-leaved lime or hazel may be prominent depending on site conditions.
These woodlands often develop on limestone and other calcareous substrates, including steep slopes, ravines, flushes and rocky outcrops. Many upland mixed ashwoods are ancient woodland, while others represent long-established secondary woodland that retains strong ecological continuity.
Why It Matters for BNG
Upland mixed ashwoods are a high distinctiveness priority woodland. Loss is subject to strict trading rules and normally requires like-for-like or higher replacement, making impacts difficult and costly to offset. Retention and buffering of existing ashwoods is often the most effective way to manage BNG risk on upland or limestone-influenced sites.
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Where You'll Find It
Upland mixed ashwoods occur across upland Britain and Northern Ireland, concentrated over limestone and calcareous substrates in areas such as the Derbyshire Dales, North Wales, the Pennines, and scattered northern limestone regions. They typically occupy ravines, valley sides, limestone pavements, and base-rich flushes, often in mosaic with calcareous grassland and rocky outcrops.
Soil & Site Requirements
Upland mixed ashwoods require base-rich or calcareous soils, typically over limestone, dolomite, or other alkaline bedrock. They can also develop on more acidic soils where base-rich water flushes through. Sites are often steep, rocky, or with shallow, well-drained soils, though some stands occur on damper ground with alder in wet flushes.
How New Upland Mixed Ashwood is Created
Inputs
• Retain or establish base-rich soil conditions
• Use locally appropriate native broadleaved species
• Avoid fertiliser, soil improvement or conifer planting
• Protect establishing trees from grazing
Management
• Encourage natural regeneration through small canopy gaps
• Control grazing pressure from livestock and deer
• Retain standing and fallen deadwood
• Avoid intensive forestry operations
Landscape
• Focus creation or expansion adjacent to existing ashwoods
• Link woodland to calcareous grassland and scrub
• Maintain natural woodland edges and transitions
How Existing Upland Mixed Ashwoods Is Improved
Inputs
• Reduce grazing pressure to allow regeneration
• Under-plant with appropriate native species where needed
• Remove or thin non-native conifers and invasive species
Management
• Promote mixed age structure and layered canopy
• Retain veteran trees and deadwood
• Manage ash dieback adaptively without wholesale removal
Landscape
• Buffer woodland edges with scrub or grassland
• Improve connectivity between woodland blocks
• Expand woodland onto suitable adjacent base-rich land
Target Condition
Upland mixed ashwoods in their defined BNG condition should:
• Be dominated by native broadleaved species typical of ashwood
• Show mixed age and height structure
• Support active natural regeneration
• Contain standing and fallen deadwood
• Support characteristic ashwood ground flora
• Have low invasive non-native species cover
• Be managed with minimal damaging disturbance
The BNG Value of Upland Mixed Ashwood
• Distinctiveness: High
• Condition Potential: Moderate to high where grazing and regeneration are managed
• Restoration Pathway: Enhancement of existing woodland rather than new creation
• Strategic Value: Key habitat for upland woodland networks and limestone landscapes
Species Typical of Upland Mixed Ashwoods
Canopy or Primary Layer
• Ash (Fraxinus excelsior)
• Wych elm (Ulmus glabra)
• Small-leaved lime (Tilia cordata)
• Oak species (Quercus spp.)
• Birch (Betula spp.)
• Rowan (Sorbus aucuparia)
Shrub or Secondary Layer
• Hazel (Corylus avellana)
• Hawthorn
• Holly
• Guelder rose
• Yew in some stands
Ground Flora or Understorey
• Dog’s-mercury
• Ramsons
• Herb-Paris
• Wood crane’s-bill
• Solomon’s-seal
• Ferns, bryophytes and calcareous mosses
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Frequently Asked Questions
What is Upland Mixed Ashwood?
Upland Mixed Ashwood is a priority broadleaved woodland found on base-rich upland soils, often ancient and species rich.
How is BNG measured here?
By area, high distinctiveness and woodland condition score using the Statutory Biodiversity Metric.
How can I achieve BNG?
Primarily through enhancement of existing ashwoods by improving structure, regeneration and species composition.
What is the BNG target condition?
Moderate to Good condition, reflecting structurally diverse, regenerating woodland.
What management is required?
Grazing control, retention of deadwood, invasive species management and adaptive response to ash dieback.
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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