Biodiversity Net Gain
From 12th February the law will require all development projects to ensure that they generate an increase of at least 10% in biodiversity, either on-site or by off-setting. We are passionate about making sure our projects surpass this expectation. If you are a developer or architect and need advice on meeting Biodiversity Net Gain (BNG) we also offer a consultation service.
Biodiversity Net Gain explained for developers and landscape architects
Why was biodiversity net gain legislation introduced?
Britain has lost more of its nature than most other countries in the world.
98% of wildflower meadows in England and Wales have been destroyed; three-quarters of ponds and heaths have vanished; half the remaining fragments of ancient woods have been destroyed.
Since 1970, more than half of Britain’s farmland birds have disappeared, while a quarter of mammals are endangered and three-quarters of butterfly species have declined.
In England, overall 1 in 10 species are threatened with extinction; 500 species have already disappeared.
According to the latest State of Britain's hedgehogs report, numbers of hedgehogs have fallen by up to 30% in urban areas and 50% in rural areas since the Millennium.
Most alarmingly, this dramatic loss of biodiversity has accelerated in the last decade. (1)
What do developers and landscape designers need to avoid?
Do not under any circumstances clear or destroy vegetation on the site. What might look like a bit of scruffy old scrub could be habitat gold and removing this could have serious consequences for the BNG assessment. The ecologist assigned to your project may refer to previous aerial photos of the site and will note the higher-quality habitat, meaning that achieving a net gain could be harder. So always allow ecologists to assess the site before any development begins.
Before negotiating on land purchases, get an opinion from an ecologist as to what the developable area of the site may be as this will affect the value and viability of a scheme. Invest a penny to save a pound!
Take your landscape architect and ecologist for a walk around the site from the very outset, to carefully note what is there and the potential for what can be achieved. Make sure that the project is landscape-led, which means……..
What do developers and landscape designers need to do?
Remember that nature is a network and does not work in isolation. Habitats are like stepping stones, helping wildlife to move between isolated patches of green space on nature’s highways, foraging for food and a place to stay along the way. We need to include ‘service stations’, places to refuel and recuperate, and more permanently, places to live and breed.
Create a mosaic of different habitat types. The most habitable spaces for wildlife are places where different habitat types (ecotones) overlap, for example, the edge of a wetland where a dry area such as a playing field transitions to a wet area such as a pond.
Think beyond hedgehogs and bees. We need to consider all the layers that form a habitat including the different levels of tree tops, the world under soil level as well as areas of water. This means planning for invertebrates, reptiles, small mammals, amphibians, birds, insects, fish, mycorrhiza and soil organisms.
Evidencing biodiversity net gain in planning documents
Developers are already being asked to determine and evidence a project’s final BNG value using the specified DEFRA biodiversity metric 4 if they want their plans to move through the planning process swiftly. This will be mandatory in January 2024 for larger development sites and for all planning applications in April 2024.
Planning Authorities can set their own level of net gain requirements and some are as high as 30%, all the Local Authorities in Gloucestershire have set the level at a minimum 10%.
Developers will need to demonstrate the following mitigation measures:
AVOID Take measures to avoid biodiversity impacts. This could mean purchasing less of the site.
MINIMISE Reduce the duration, intensity, extent and/or likelihood of impacts that cannot be avoided.
MITIGATE WITH ON-SITE RESTORATION Enhance or recreate habitats after development, where avoidance or minimisation is not possible.
OFF-SITE COMPENSATION Measures taken to compensate for any residual adverse impacts after full implementation of the previous three steps of the Mitigation Hierarchy.
You will not get validation on planning applications without the assessment, the design, and the fully costed management plan. Here are some aspects to consider:
BNG must be Achieved “in perpetuity” (in practice, a minimum 30 years management regime).
Delivery mechanisms must be secured at the planning stage (with costed management plans) delivering a minimum 10% net gain.
The plan should include monitoring over the full span of the delivery period (30 years).
Developers cannot ‘trade down’ higher-value habitats for lower-value ones.
There is hope for development…
If your starting point is more like this, then you can easily make a net gain of way more than 10%
And if there are no existing habitatsthere is nothing to enhance
When in a project to begin thinking about biodiversity net gain
BNG must be considered at the earliest possible stage of any proposal. Ideally, this should be undertaken at the site selection stage. There is an element of due diligence required when land is being considered for potential purchase and/or promotion for development on the net gain implications and potential costs.
Having a clear understanding of the site you propose to select, and its biodiversity unit value upfront will determine the feasibility of delivery making it easier and more cost-effective to protect biodiversity from the outset.
Rachael is an award-winning landscape designer and the co-director of Austin Design Works. A chartered member of the Landscape Institute since 2001 and a professional member of the Society of Garden Designers, Rachael takes an approach to design that enhances and works with nature and improves the wellbeing of people who live and work in the places she creates, such as the Museum in the Park in Stroud. Operating throughout the south and southwest of England, she uses her experience to collaborate with ecologists and consultants in achieving Biodiversity Net Gain, ensuring that each development results in a richer habitat for nature and wildlife than before it was there.
Statistics are from October 2020. https://www.wwf.org.uk/future-of-UK-nature