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?
Hazel Scrub
Hazel scrub is a native scrub habitat dominated by hazel, typically forming dense multi-stemmed shrubs or coppice stools usually less than 5 metres in height. It commonly occurs along woodland edges, ride margins, hedgerow networks and as transitional scrub developing on former grassland or farmland.
Hazel scrub provides structural habitat for birds and small mammals and produces nuts, catkins and leaf litter that support invertebrates and woodland food webs. It may also function as a transitional habitat facilitating woodland regeneration.
Lowland Heathland
Lowland heathland is a semi-natural habitat dominated by dwarf shrubs growing on nutrient-poor, acidic soils in the lowland zone, generally below about 300 metres above sea level. The vegetation is typically dominated by ericaceous species such as heather, bell heather, and cross-leaved heath, often with gorse species.
Lowland heathland usually occurs as a mosaic habitat, containing patches of dwarf shrub heath alongside acid grassland, bare ground, scattered scrub or trees, and occasionally wet heath or small bog areas.
Bramble Scrub
Bramble scrub is a dense scrub habitat dominated by bramble , typically forming thick thickets between 2 and 3 metres in height. It commonly occurs along woodland margins, grassland edges, road and rail embankments, brownfield land and other disturbed areas as part of natural vegetation succession. All bramble scrub parcels are also recorded as poor condition in the metric, regardless of their structure or species composition.
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