Biodiversity Units: What are they?

Biodiversity net gain (BNG) is a concept and approach used in conservation and environmental management that aims to ensure that development projects have a positive impact on biodiversity. The idea behind biodiversity net gain is that when a development project takes place, the loss of biodiversity resulting from construction or land use changes should be offset by creating or enhancing existing habitats elsewhere so that there is a “net gain” in biodiversity overall.

Biodiversity units have been established to facilitate the measurement and calculation of the biodiversity significance of developed land. The utilisation of BNG units is increasingly prevalent, given that biodiversity net gain is poised to become compulsory criteria for all forthcoming planning permissions and development undertakings in England at the end of 2023.

What are Biodiversity Units?

BNG entails quantifying the change in biodiversity values that arise from development ventures. Biodiversity units encompass the standardised metrics employed to evaluate biodiversity gains, encompassing factors like species count, habitat types, ecological functionality, among others. These units dedicated to biodiversity net gain are subsequently used to determine whether any corrective actions might be necessary to fulfil planning commitments set by the local planning authority.

To calculate the enhancement and measure biodiversity, the quantity of units is increased by a minimum of 10%. This numerical value constitutes the delivery in net gain that must be achieved to secure permission for the development site or area of land in which the project will take place.

The integration of biodiversity net gain can be realised on-site and is expected to be maintained for at least 30 years. If achieving a net gain of 10% or more on-site proves unattainable, and its continuity can’t be fully maintained on-site, the remaining portion can be offset and accommodated off-site, utilising biodiversity banking.

How are Biodiversity Units calculated?

Biodiversity units are calculated by comparing the biodiversity value of a site before development to the value after development, focusing on losses and gains of biodiversity.

To calculate BNG, the following steps can be taken:

  1. Identify the baseline biodiversity value of the site before development. This can be done by conducting a habitat survey to identify the different habitats and species present on the site and their relative importance in terms of biodiversity.
  2. Determine the biodiversity value of the site after development. This involves assessing the quality and quantity of the habitats that will be created or enhanced as a result of the development. The value of the habitats can be assessed using a standardised biodiversity metric 4.0 calculation, which takes into account factors such as habitat quality, rarity of species, and connectivity with other habitats. For small designated sites, metric users can utilise the small site metric for biodiversity, which is a simplified version of the 4.0 metric by Natural England.
  3. Calculate the net gain in biodiversity. Measuring biodiversity net gain is done by subtracting the baseline biodiversity value from the biodiversity value after development. If the biodiversity value after development is higher than the baseline value, the net gain will be positive.
  4. Implement measures to enhance biodiversity on site if necessary to achieve a positive net gain. This may involve incorporating features such as green roofs, planting native vegetation, planting hedgerows and lines of trees, and creating wildlife corridors to improve habitat quality and connectivity.

It’s important to note that the biodiversity net gain metric 4.0 is a complex process that requires input from ecologists, planners, land managers and other experts. It’s recommended that you work with a qualified professional to ensure that your calculations are accurate to achieve biodiversity gains.

Why is Biodiversity Net Gain Important?

Biodiversity net gain is important for several reasons, as it addresses crucial environmental, economic, and social concerns. Here are some key reasons why biodiversity net gain is considered important:

  • Conservation of Ecosystems and Species: Biodiversity is essential for the health and resilience of ecosystems. It ensures that ecosystems can continue to provide services like clean water, pollination, carbon sequestration, and soil fertility. By focusing on net gain, we can actively work to enhance and restore habitats, which can aid in the conservation of threatened species and ecosystems.
  • Mitigation of Habitat Loss: As human activities expand, habitats are often lost or degraded due to development projects. Biodiversity net gain helps counterbalance this loss by requiring developers to create or enhance habitats elsewhere, minimising the negative impact on overall biodiversity.
  • Climate Change Resilience: Diverse ecosystems are often more resilient to environmental changes, including those brought about by climate change. Biodiversity net gain can contribute to building ecological systems that are better equipped to withstand disruptions.
  • Legal and Regulatory Requirements: Many regions and countries are integrating biodiversity net gain into their legal and regulatory frameworks. This means that developers are legally obligated to consider biodiversity and take steps to ensure a positive impact on biodiversity as a condition for obtaining permits for development projects.
  • Sustainable Development: Biodiversity net gain promotes the idea that economic development and environmental conservation are not mutually exclusive. It encourages a more balanced approach that seeks to harmonise development goals with long-term ecological health.
  • Enhanced Public Perception: Organisations and projects that prioritise biodiversity net gain are often viewed more favourably by the public, investors, and stakeholders who are concerned about environmental issues.
  • Long-Term Planning: Biodiversity net gain plans encourage a focus on the long-term sustainability and strategic significance of development projects. By considering the impact on biodiversity, developers are compelled to think beyond short-term gains and consider the legacy of their actions.

Why Choose Collington Winter?

Our team of biodiversity net gain consultants have helped numerous clients in delivering BNG over the years. Biodiversity is something that we are experienced and qualified in, and we can offer advice on your development project. We are determined to offer you the support you need to meet the required biodiversity bracket.

Please get in touch if you would like further information about biodiversity net gain credits or conservation covenants. Our Director, Olivia Collington, holds a Natural England license. If you would like to find out more about any of the services we provide, please feel free to contact us using the details below.

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