The Solent Forum

Working in partnership for the future

Biodiversity Net Gain

The Environment Act 2021 provides for net gain by way of amendments to the Town and Country Planning Act 1990 and the Planning Act 2008. Development on land and in intertidal locations will be required to deliver a mandatory Biodiversity Net Gain (BNG). There is a separate system that applies to marine development and Marine Net Gain which is currently under development.

BNG is an approach to development that seeks to leave biodiversity in a better state than before. Where a development has an impact on biodiversity it encourages developers to provide an increase in appropriate natural habitat and ecological features over and above that being affected. It is hoped that the current loss of biodiversity through development will be halted and ecological networks can be restored. It relies on the application of the mitigation hierarchy to avoid, mitigate or compensate for biodiversity losses. It uses a metric as a proxy for recognising the negative impacts on habitats arising from a development and calculates how much new or restored habitat, and of what types is required to deliver sufficient net gain. Natural England have produced an introductory brochure to net gain and a case study on how it can be applied to port development.

BNG Key Facts (source Natural England):

Proposed BNG Timetable

Summer 2021:

Spring 2022:

Spring 2023:

Autumn 2023:

What is Environmental Net Gain?

‘Environmental Net Gain’ is a term that covers multiple environmental benefits. Whilst ENG does not yet have a single agreed definition, in Defra’s public consultation on Biodiversity Net Gain (BNG) it was defined as: “In short, this means improving all aspects of environmental quality through a scheme or project. Achieving environmental net gain means achieving biodiversity net gain first, and going further to achieve increases in the capacity of affected natural capital to deliver ecosystem services and make a scheme’s wider impacts on natural capital positive.” 

Marine Net Gain

Many marine developments ultimately land onshore and therefore also have terrestrial and intertidal elements. Planning, consenting, and licensing regimes, and their respective net gain regimes, may overlap in certain circumstances. Defra have committed to ensuring that marine net gain is as coherent and consistent with land-based Biodiversity Net Gain as possible, minimising the burden on developers. The intention is that only one net gain regime will apply to each element of a development. Marine net gain will only apply to developments, or infrastructure forming part of development, below the Low Water Mark and land-based Biodiversity Net Gain will apply to onshore and intertidal developments, down to the Low Water Mark.

ABPmer prepared a paper for the OWEC Strategic Task and Finish Group on strategic targets for marine and intertidal net gain.

Chichester Harbour Protection and Recovery of Nature

To ensure the best outcomes for Chichester Harbour, the Conservancy have formed a steering group with the Environment Agency, Natural England, Sussex IFCA, and Coastal Partners to protect, restore, and deliver ‘net gain’ for nature. This will help plan, coordinate and manage work over the next 10 – 25 years. This initiative should enable it to source new funds, increase ‘blue’ investments, and bring the wider community together to deliver a programme of actions. The initiative known as Chichester Harbour Protection and Recovery of Nature (CHaPRoN for short) will focus on priority habitats such as saltmarsh, seagrass, and oysters, as these are at the biggest risk of further loss, have a high natural capital value, and are great at carbon fixing. The ambition is wider though and will seek to create wildlife recovery areas stretching from Langstone Harbour in the West to Pagham Harbour in the east and linking terrestrially to the South Downs National Park a mile to the north of Chichester Harbour AONB.


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