ProHort provides Biodiversity Net Gain Assessments and Biodiversity Gain Plan support for development projects throughout Hampshire. From the chalk streams of the Test and Itchen to the Solent coastline, New Forest and South Downs, we help clients understand their BNG requirements and plan how biodiversity gains can be achieved.
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The Biodiversity Gain Plan is the mechanism used to discharge the statutory biodiversity gain condition where it applies. Planning permission alone does not mean development can begin: the relevant Biodiversity Gain Plan must first be approved by the planning authority.
ProHort can support Hampshire BNG condition discharge by helping bring the relevant ecological and planning information together. This may involve:
Reviewing the existing BNG assessment, metric calculation and planning permission.
Checking that the proposed habitat measures reflect the approved site layout.
Setting out how on-site habitat creation and enhancement will contribute to the required biodiversity gain.
Including details of registered off-site biodiversity units or statutory credits where relevant.
Preparing the supporting information and documentation for submission.
Assisting with relevant queries or amendments requested during the approval process.
The plan should be prepared around the actual permission and development proposals, rather than relying on a generic document. Where a scheme is phased, additional overall and phase-specific Biodiversity Gain Plan requirements may apply.
We support projects across: Winchester, Southampton, Portsmouth, Basingstoke, Eastleigh, Fareham, Gosport, Andover, Havant, Ringwood, New Forest and all surrounding areas.
A Biodiversity Net Gain Assessment in Hampshire establishes the biodiversity value of a site before development and calculates how the proposed works may affect its habitats. It provides the baseline information and metric calculations needed to understand the biodiversity impact of a scheme and identify opportunities to deliver measurable gains.
Where the statutory BNG condition applies, development is generally required to achieve at least a 10% increase in biodiversity value. The assessment helps establish the starting position and informs the approach to meeting that requirement.
Our BNG assessment for development in Hampshire can include:
Habitat surveys and mapping to identify and record the habitats within the development boundary.
Habitat condition assessments to establish the condition and distinctiveness of relevant habitat parcels.
Biodiversity metric calculations using the applicable statutory biodiversity metric.
Biodiversity Net Gain reporting setting out the site’s baseline value and the anticipated post-development position.
Habitat retention and enhancement advice to inform site layouts and landscape proposals.
Biodiversity uplift recommendations where further on-site or off-site measures may be needed to achieve the required gain.
A detailed biodiversity metric assessment can help developers understand ecological constraints before designs are finalised. It can also help identify where changes to the layout, retained habitats or proposed landscaping may improve the project’s BNG position.
A Biodiversity Gain Plan in Hampshire sets out how a development will meet the biodiversity gain objective. It is a separate stage from the initial BNG assessment and, where the statutory biodiversity gain condition applies, must be submitted to and approved by the relevant planning authority before development begins.
The plan brings together the approved development proposals, biodiversity metric information and details of how the required gains will be delivered. It should clearly explain the proposed habitat creation and enhancement, any off-site biodiversity gains and the arrangements for securing and managing those measures.
ProHort provides Biodiversity Gain Plan services in Hampshire to help clients prepare the information required for this stage of the planning process.
Depending on the development, a Biodiversity Net Gain Plan may cover:
Approved biodiversity metric calculations showing the proposed post-development biodiversity value.
On-site habitat creation and enhancement, including the location, type and extent of proposed habitat measures.
Off-site biodiversity units, where eligible registered gains are being used and allocated to the development.
Statutory biodiversity credits, where these form part of the proposed approach.
Habitat management and monitoring arrangements, including relevant long-term responsibilities.
Supporting plans and evidence required to explain how the biodiversity gain objective will be achieved.
A well-prepared Biodiversity Gain Plan for development in Hampshire should be consistent with the planning permission, approved drawings and metric calculations. This helps the planning authority understand how the proposed biodiversity gains will be delivered.
Hampshire has a varied natural environment, from internationally important coastal habitats to chalk streams, heathland, ancient woodland and open downland. These local characteristics can influence the habitats found on development sites and the opportunities available for biodiversity enhancement.
The Solent and its surrounding coastline include a range of coastal and intertidal habitats, including saltmarsh, mudflats, coastal grazing marsh, vegetated shingle and saline lagoons. Portsmouth Harbour, Southampton Water and the wider Solent coastline are important parts of this landscape.
Development around Southampton, Portsmouth, Fareham, Gosport and Havant may need to consider the habitats present within and around the site, as well as wider coastal and estuarine ecological constraints. Accurate habitat classification is important where coastal or wetland features form part of the site’s biodiversity baseline.
The Test and Itchen are well-known Hampshire chalk streams, supporting distinctive aquatic and riverside environments. Their catchments include water meadows, riparian vegetation, wetlands and other habitats connected to the river network.
For development around Winchester, Andover, Romsey and the wider Test and Itchen catchments, it is important to identify any watercourse-related habitats and consider their condition and ecological connections. The presence of a chalk stream may also bring wider ecological or water environment considerations that need to be considered separately from the BNG metric.
The New Forest is recognised for its extensive mosaic of heathland, woodland, grassland, wetland and open habitats. The wider landscape also contains ponds, mires and other wet features that contribute to its ecological character.
Development in or around the New Forest should be informed by the habitats actually present on the site and any relevant designated-site or protected-species considerations. The BNG assessment should accurately record the baseline rather than assuming that all heathland, grassland or woodland parcels have the same ecological value.
The South Downs landscape includes chalk downland, species-rich grassland, woodland, scrub and farmland habitats. These features can be relevant to development proposals around Winchester, Petersfield, Alton and other settlements within or near the National Park.
Where chalk grassland or other semi-natural habitats are present, their condition and distinctiveness can have an important bearing on the biodiversity metric calculation. Retaining valuable habitat features and considering suitable enhancement opportunities at an early stage can help inform the development layout.
Across north-east Hampshire, including areas around Basingstoke, Fleet, Farnborough and Yateley, heathland, woodland, scrub and grassland form part of the wider ecological landscape. Some areas are also connected to the Thames Basin Heaths and Wealden Heaths landscape.
Development proposals in these locations should consider the habitats within the site boundary and any relevant nearby ecological designations. Existing woodland, heathland and connecting habitat features may influence both the baseline calculation and the scope for appropriate habitat enhancement.
Hampshire’s Local Nature Recovery Strategy (LNRS) was published on 8 December 2025. It sets out local priorities for nature recovery and identifies areas where habitat creation, restoration and improved ecological connectivity could make a valuable contribution.
The strategy reflects Hampshire’s varied landscapes, including chalk farmland, rivers and wetlands, woodlands, heathlands, coastal and marine environments, and urban areas. Its Local Habitat Map can provide useful context when considering where habitat enhancement proposals may support wider nature recovery priorities.
For developers, the LNRS can help inform the location and type of habitat measures being considered. However, it does not replace a site-specific BNG assessment or the statutory biodiversity metric. The site’s existing habitats must still be surveyed and assessed, and any proposed gains need to be suitable for the development and the relevant statutory requirements.
ProHort can help clients consider Hampshire’s nature recovery priorities alongside the ecological characteristics and practical requirements of their individual projects.
Whether you need a Biodiversity Net Gain Assessment for a proposed development or a Biodiversity Gain Plan to support Hampshire BNG condition discharge, ProHort can help you understand the ecological information and documentation required.
Contact our team to discuss your project and the support you need.
Where a development site contains or adjoins a chalk stream, the assessment should identify the relevant watercourse and associated habitats, such as riparian vegetation, wetland or water meadow features. Their condition and distinctiveness can influence the biodiversity metric. Other water environment and designated-site considerations may also apply, but these are separate from the metric calculation itself.
No. Nutrient neutrality and Biodiversity Net Gain are separate requirements. Nutrient neutrality addresses the effects of additional nutrient pollution on sensitive water environments, while BNG concerns measurable changes in the biodiversity value of habitats. A development in a relevant Solent catchment may need to consider both, and one does not automatically satisfy the other.
Development within a National Park is not automatically exempt from statutory BNG. Whether the biodiversity gain condition applies depends on the development’s circumstances, including the relevant exemptions and transitional provisions. Where it does apply, the required biodiversity gain must be addressed alongside any separate landscape, habitat and designated-site considerations.
Yes. Previously developed sites, including former military or institutional land, can support valuable habitats such as heathland, scrub, species-rich grassland, ponds and bare-ground mosaics. The site’s former use does not determine its biodiversity value. A site-specific habitat survey is needed to establish what is present and how it should be assessed.
Certain habitats, including ancient woodland, are classed as irreplaceable habitats under the statutory BNG framework. They are not treated as ordinary habitat parcels where impacts can simply be balanced through a standard biodiversity unit calculation. Avoiding impacts is particularly important, and the relevant statutory requirements and planning considerations must be addressed where irreplaceable habitats are present.
The information will depend on the permission and the development, but the Biodiversity Gain Plan will generally need to set out the approved post-development biodiversity value, on-site habitat proposals, any registered off-site gains or statutory credits, and relevant supporting evidence. It should be consistent with the approved plans and metric calculation. The relevant planning authority must approve the plan before development begins where the statutory biodiversity gain condition applies.
