Policy BG/BG: Biodiversity and geodiversity

Biodiversity Net Gain (BNG)

5.6.  BNG has been identified as a mechanism for the restoration of biodiversity across the UK. National planning policy sets out a requirement for developments to achieve biodiversity net gain, and the Environment Act 2021 sets a mandatory statutory minimum of 10% biodiversity net gain above the ecological baseline for the application site.

5.7.  Cambridgeshire currently has one of the smallest areas of land managed for nature of any county in the country, relative to its size. The local need for biodiversity restoration is also recognised within the Cambridgeshire Doubling Nature vision, aiming to increase land managed for nature from around 8% to 16% (the national average). Considering this, together with the relatively low level of designated sites and priority habitats that Greater Cambridge has compared with other English areas, highlights the need for development to bring further net gains beyond the 10% required nationally.

5.8.  Net gains in biodiversity can be delivered by most development by following the mitigation hierarchy principles and understanding the ecological opportunities and constraints on-site at the earliest stages of design. However, the opportunity for smaller sites to deliver meaningful BNG can be constrained by size and available open space, with these sites having fewer opportunities to deliver biodiversity net gain. Private gardens’ classification within the Statutory Biodiversity Metric as low-value habitats post-development, (i.e. vegetated garden) and also, the inability to count tree planting, small ponds or creating wildlife-friendly gardens as biodiversity gain can lead developers to have to look for off-site units or statutory credits to deliver BNG, even when delivering a minimum of 10% biodiversity net gain. Therefore, requiring smaller sites to deliver 20% biodiversity net gain would be unreasonable, and may impact viability. However, where opportunities arise to secure BNG on exempted sites, or where there are opportunities for minor development to bring further net gains beyond the 10% required nationally, this is also encouraged.

5.9.  The Councils preference is for BNG to be delivered on-site wherever possible, (rewarded through the Defra Statutory BNG metric) and in accordance with the Biodiversity Gain Hierarchy (BGH), which emphasises prioritising on-site measures before exploring off-site options, ensuring developments make the most effective contributions to local biodiversity. However, on-site delivery may be poor quality, suffer from disturbance and pollution, and cannot always be secured effectively for 30 years. This increases the likelihood that developments will deliver less than the required net gain or result in a biodiversity loss. In certain circumstances off-site delivery may therefore be the best option, particularly if it is well-related to and relatively local to the development.

5.10.  When on-site gains are not feasible, an offsite approach to BNG allows developers to achieve biodiversity gains through habitat enhancement on other land. Off-site BNG allows for strategic delivery of BNG but may be a less desirable option in some cases as it is removed from the immediate impact of the development on both local biodiversity and the local community. Off-site measures will only be considered where it can be demonstrated that, after following the mitigation hierarchy, all reasonable opportunities to achieve meaningful net gains on-site have been exhausted.

5.11.  Where the full required net gain cannot be achieved on a development site or where off-site delivery is decided to be the feasible and effective option, the remaining gain may be achieved outside the development site, either by the developer or by a third party. In the unlikely event that the required gains cannot be provided through these routes, the Council may negotiate a justified and proportionate financial contribution which will be used to secure the required gain by obtaining credits from a ‘habitat bank’. Delivery of off-site biodiversity gains through statutory biodiversity credits is the last resort for development which is unable to meet BNG requirements on or off-site.

5.12.  Where off-site habitat measures are required, applicants must provide UK habitat assessment surveys to agree a baseline metric of the existing offsite habitats, conform to BNG CIEEM/IEMA/CIRIA-Good Practice Principles for Development and seek to deliver BNG as close as feasible to the impacts of the development.

5.13.  Upon submission of development proposals subject to mandatory BNG, the Defra Biodiversity Metric trading rules should also be observed. Submission of a completed Statutory Biodiversity Metric (SBM) must be submitted as part of the Biodiversity Gain Plan, evidencing how biodiversity net gain will be achieved.

5.14.  When considering local BNG proposals the LPA will seek to ensure that BNG is the primary use of the space and is ecologically viable. Proposals will require agreement with the LPA’s ecologist that they provide a long-term benefit to local biodiversity that is compatible with other site uses such as recreational space or sports pitches.

5.15.  To ensure the delivery of BNG measures, the Councils will secure off-site habitat creation and its long-term management (minimum 30 years), through planning obligations, or, where BNG is provided on land outside of the applicant’s control, by obligations. A Habitat Management Monitoring Plan (HMMP) is required to support off-site land proposals and will be reviewed and agreed by the LPA as part of the legal agreement process. Significant on-site enhancements will also require a HMMP to set out how these habitats will be established and managed. The HMMP will be submitted and agreed alongside the Biodiversity Gain Plan to discharge the pre-commencement biodiversity gain planning condition.

5.16.  The full Biodiversity Gain Plan will be submitted either with the planning application or after the permission is granted, but before development has commenced. If not submitted with the planning application, the submission and approval of a Biodiversity Gain Plan before development commences will form a condition of any planning application approval.

Inter-relationship between Biodiversity Net Gain, Urban Greening Factor and Green infrastructure

5.17.  The Urban Greening Factor (UGF) and BNG are separate requirements. Where protected species or priority habitats or species are found on a development site or a proposed development may impact a Site of Importance for nature conservation, the requirements of Policy BG/BG should be met in addition to the relevant targets of Policy BG/UGF.

5.18.  Green infrastructure (GI), an important element including trees, accessible natural greenspace and soft edges, should be included in all new developments (see Policy BG/GI). While GI does count toward BNG scores, it is recognised that on-site BNG invariably forms part of a multifunctional GI space and may not be the primary function, for example existing alongside recreational space or Sustainable Drainage Systems (SUDs); this can lead to compromises in habitat creation and long-term value of the new habitats, and in these circumstances off-site BNG provides a more sustainable option.

The LNRS and BNG

5.19.  BNG follows the ‘proximity principle’ which means that if BNG cannot be achieved on-site after consulting the mitigation hierarchy, off-site opportunities should be identified with a priority given to local enhancements where possible. The metric penalises proposals where offsite habitats are removed from the site of impact to avoid reducing biodiversity in the local area and to recognise the importance of ecosystem services to the local community. Therefore, where it is necessary to use a biodiversity offset site, the policy encourages delivery within sites identified within the LNRS priority areas. This is because where BNG is delivered off-site within these identified priority areas, the ‘strategic significance’ multiplier can be applied within the Statutory Biodiversity Metric; increasing the value of those habitat credits over and above credits created outside of these strategically important areas. This applies whether the BNG is on-site, off-site or part of a habitat bank. This has the effect of incentivising delivery of measures that will deliver against LNRS priorities in the most effective locations.

Sites and Habitats for Biodiversity in Greater Cambridge

5.20.  The NPPF (2024) states that to protect and enhance biodiversity and geodiversity, plans should identify, map and safeguard components of local wildlife-rich habitats and wider ecological networks, including the hierarchy of international, national and locally designated sites of importance for biodiversity, wildlife corridors and stepping stones that connect them, along with areas identified by national and local partnerships for habitat management, enhancement, restoration or creation.

5.21.  Greater Cambridge has a range of important sites and habitats for biodiversity, recognised through designations, from international to local importance. Some of these are also of geological importance. Sites of Biodiversity or Geological Importance are identified on the Policies Map and these represent a tiered network for the conservation of biodiversity and geodiversity within Greater Cambridgeshire. These sites include:

• Statutorily protected international Special Areas of Conservation (SACs) and Special Protection Areas (SPAs);
• National Sites of Special Scientific Interest (SSSIs); and
• Local Nature Reserves (LNRs), Local Geological Sites (LGS) (worthy of protection for their Earth Science or landscape importance but not already protected as SSSIs), County and City Wildlife Sites (CWSs and CiWSs), and Protected Road Verges (PRV) are non-statutorily protected sites of local importance (sites without statutory protection designated at a local level).

5.22.  European sites (SACs and SPAs) are protected by the Conservation of Habitats and Species Regulation 2017 as amended (the Habitats Regulations) and the Councils must carry out a habitats regulations assessment (HRA) to test if a plan or project proposal could significantly harm the designated features of a European site. Plans or projects which may have a likely significant effect on a European site will require appropriate assessment. Natural England will be consulted on any planning application in or adjacent to a European Site, or any such candidate site.

5.23.  The Habitats Regulations impose a strict negative test that permission can only be granted if it can be concluded that there will be no adverse effect on the site's conservation objectives. Derogations are only permitted where there are no alternative solutions, and there are imperative reasons of overriding public interest and only then through provision of compensation. As such these tests are at a significantly higher level than would be applied to nationally or locally designated sites.

5.24.  At present the only site of international importance within Greater Cambridge is the Eversden and Wimpole Woods SAC (the SAC is shown on the Policies Map). The site provides a habitat for a breeding colony of the Barbastelle bat, one of the rarest bats in Western Europe. The bats have been recorded at a small number of other sites up to eleven kilometres from the Woods. Proposals coming forward on sites within the Natural England Impact Risk Zone for the Eversden and Wimpole Woods SAC and/or identified as having moderate or high suitability to support Barbastelle bats are required to demonstrate that development will not have an adverse impact on their habitat and foraging areas and commuting flight paths. If mitigation is required, this will ensure the avoidance of key habitat features likely to be used by the bats and the creation and enhancement of suitable habitat for this species. Development proposals should have regard to the DEFRA Eversden and Wimpole Woods SAC Barbastelle Bat Protocol (or successor document).

5.25.  There are a number of other sites within the surrounding districts, which are considered as part of any Habitat Regulation Assessment carried out by the Councils, because of their proximity to Greater Cambridge and/or the nature of their conservation interest:

• Ouse Washes SAC and SPA
• Fenland SAC (Woodwalton Fen, Chippenham Fen, Wicken Fen)
• Portholme SAC
• Devil’s Dyke SAC
• Breckland SAC and SPA.

5.26.  SSSIs are statutorily protected by their designation under the Wildlife and Countryside Act 1981 and the Natural Environment and Rural Communities Act 2006. Where a development proposal has the potential to impact a SSSI, Natural England will be consulted where required.

5.27.  Cambridge City Council has declared 12 Local Nature Reserves (LNRs) on land that it owns and manages, including a number of the city’s commons, and Cambridgeshire County Council has declared 5 LNRs on land that it owns and manages in South Cambridgeshire. LNRs are statutorily designated by local authorities under Section 21 of the National Parks and Access to the Countryside Act 1949. County Wildlife Sites (CWSs) and City Wildlife Sites (CiWSs) (which also include a number of the city’s commons) have been selected as sites of substantive nature conservation interest against Cambridgeshire and Peterborough’s County Wildlife Sites System selection criteria, as a result of surveys undertaken for the Council by the local Wildlife Trust and maintained by the Cambridgeshire and Peterborough Environmental Records Centre (CPERC).

5.28.  Other undesignated green spaces also make up the ecological network of sites across the city and would be subject to this policy, if they are identified as meeting the criteria for Local Site status following the County Wildlife Sites System.

Survey Information and Site Assessment

5.29.  Prior to the determination of any development application (unless exempt under the Environment Act 2021), survey information and site assessment that is proportionate to the likely severity of impacts must be provided by applicants. Submitted documentation should be produced having regard to the guidelines for Ecological Impact Assessment produced by the Chartered Institute of Ecology and Environmental Management and relevant best practice guidance for example British Standards on Biodiversity (BS 42020, 2013 or successor documents). Documentation should demonstrate that the mitigation hierarchy has been implemented, and should evidence how the intrinsic natural features of particular interest are to be safeguarded or enhanced.

5.30.  Survey information as required by the policy could include ecological appraisal, or an assessment of recreational pressure impacts on SSSIs where relevant.

5.31.  Submitted ecological reports are expected to explain how the mitigation hierarchy has been embedded into the design of the development and to set out the steps to be followed in order of priority when delivering BNG. Where impacts on habitats and species cannot be avoided, a clear explanation is needed of why alternative sites are not feasible, and what proposed mitigation and compensation measures are necessary to address all likely significant adverse effects.

Exceptionally Permitted Development

5.32.  In exceptional cases, national planning policy allows for the development need and benefits to demonstrably outweigh the loss of irreplaceable habitat within Greater Cambridge (including (but not confined to) ancient woodlands; ancient and veteran trees; and lowland fens). These considerations and the application decision are the responsibility of the relevant Local Planning Authority.

5.33.  Any exceptionally permitted development proposals which have a direct or indirect adverse effect on sites of biodiversity or geological importance (SSSIs and other designated nature sites are identified on the policies map) and including irreplaceable habitat (as defined by The Biodiversity Gain Requirements (Irreplaceable Habitat) Regulations 2024) must seek to minimise adverse impacts and will be required to agree a bespoke compensation strategy, with the local planning authority.

5.34.  Where development resulting in the loss or deterioration of ancient woodland, ancient trees and veteran trees is exceptionally permitted, compensation measures will not be considered as part of the assessment of the development proposal, and will only be considered once the existence of exceptional circumstances has been ascertained. Any proposals which would lead to the creation of new woodland, or the restoration or improvement of ancient woodland should follow the UK Forestry Standard.

Habitat features

5.35.  Buglife (England) identifies the Fens as an Important Invertebrate Area (IIA) of national importance, which although it is a non-statutory designation, is a material planning consideration. These IIA areas support some of Britain’s rarest species and possess unique assemblages of invertebrates. There is currently a small section of IIA mapped within South Cambridgeshire, associated with the Fens IIA. The policy encourages proposals in or near to an IIA to aim to protect and enhance habitat features for invertebrates via site design (especially any onsite BNG but including Green Infrastructure) and ongoing management. All proposals in or near to an IIA should have regard to general guidance produced by Buglife.

5.36.  National Planning Policy expects development proposals to bolster wildlife by incorporating features which support priority or threatened species such as swifts, bats and hedgehogs. National planning guidance on the Natural Environment also supports the inclusion of integrated nest boxes (commonly known as swift bricks) where possible, with the general aim across a development of a minimum of one nest box per unit. Nest boxes can provide important habitat for other species as well as swifts, such as starlings and sparrows. The provision of integrated nest boxes (a combination of bird, bat & insect boxes) should accord with the supplementary guidance set out within the Greater Cambridge Sustainable Design and Construction SPD (2020), or successor document and will be secured by the LPA through condition.

For further guidance on how to submit comments, please see the Representation Guidance Note.

All comments must be received by 25 September 2026 at 5pm.