"It goes without saying that BNG has had a significant impact on the development sector. BNG must now be considered at all stages of the planning process, from validation, through to assessment, discharge of conditions and reporting"
- Mark Topping - Lanpro
Biodiversity net gain (BNG) became mandatory for major developments from 12 February and for small sites from 2 April.
Landscape architecture, ecology and arboriculture have huge synergy and, when the disciplines work in close partnership, project outcomes can be exciting, and creative and have huge benefits to the environment. As Lanpro a multi-disciplinary company in which ecologists and landscape consultants work alongside planners, we have prior experience of an environmental-led approach to development.
It goes without saying that BNG has had a significant impact on the development sector. BNG must now be considered at all stages of the planning process, from validation, through to assessment, discharge of conditions and reporting. Furthermore, the requirement to manage onsite BNG for 30 years has a significant impact on the management of schemes.
For the purposes of the regulations, BNG is measured using the biodiversity metric calculator which has been developed by Defra. Net gain is measured as the percentage change in the biodiversity value of pre and post-development habitats.
The minimum 10% gain must be achieved separately for area habitats, hedgerows and watercourses if these different categories of habitat occur within the planning boundary.
Although initiated by the previous government, the introduction of BNG is well-timed in view of the new government’s revised policy on Green Belt release. The increased flexibility regarding Green Belt release could help implement BNG as it can unlock land for development within proximity of green space, which is often of a low quality in biodiversity terms. Thus the 'grey belt' - poor quality or brownfield sites within the greenbelt – provide an opportunity for development without a considerable cost in BNG.
Most would view the policy as a net gain in many respects: over time, it will result in considerable enhancements to natural environments and will see greener, healthier developments with high-value and high-quality habitats.
It is important to remember that we are still in the early days of a very significant change in approach and that an element of confusion is inevitable. An example of this is that in some cases, developers who understand the process are looking carefully at their application boundaries in relation to the ‘red line’ (the application boundary) and the ‘blue line’ (their landholding which is not part of the development application).
In doing so, they can ensure that they are assessing only core areas and are not over-prescribing BNG. They are also considering blue line ownership opportunities and landbanks for ‘off-site’ provision of BNG.
One issue that developers must be aware of is the careful refinement of the planning ‘red line’: ensuring that areas superfluous to the development but which fall within the developer’s ownership (the ‘blue line’) are excluded from the BNG calculations. This can result in elements such as watercourses (which can be particularly challenging from a BNG perspective and require specialist ecological input) being removed from the assessment.
Another current issue in proving biodiversity net gain is a lack of registered off-setting sites, although it is hoped that this is a short-term issue. I know of several councils which are developing habitat banks but are currently in the process of finalising Habitat Management and Monitoring Plans and S106s.
In some LPAs, there currently are no registered sites for BNG. This leaves the options as onsite, in proximity subject to a legal agreement, starting negotiations with landowners, or the Environment Bank option.
Clearly one measure of the success of BNG is the roll-out of well-designed sites which achieve a 10% biodiversity uplift without losing developable land. Essentially this comes down to the appropriate design of BNG and preparing designs that are maintainable in perpetuity. Clear management plans should be created to ensure this, plans which cover the full 30-year period to ensure landscape management is adaptable to evolving aspects of increased development in proximity, environmental changes in climate and disease.
The greatest concern relating to BNG is the risk that some sites will become unviable for development. While we have not seen this specifically, we did have an urgent submission for a small site prior to the 2 April deadline which may have otherwise been unviable.
However, I suspect there are many land-banked sites which will no longer come forward as a result – though potentially those land banks could come forward as BNG sites themselves.
Inevitably there are many practical issues in relation to the provision of BNG, but essentially the principle is welcomed by those striving to create popular and environmentally responsible developments. The sense among the planning and development industry is that when these issues are ironed out, the standard of new development (and the impact on the surrounding area) will improve exponentially.
