In the face of ongoing environmental challenges, such as habitat destruction and species decline, biodiversity net gain (BNG) has emerged as a critical strategy to restore and enhance the natural environment. BNG aims to ensure that the biodiversity of an area impacted by development surpasses its original state, creating a net positive outcome. Currently mandatory in England and Wales for larger projects, BNG requirements are also gaining traction globally, with other jurisdictions, including the European Union and the United States, moving towards similar regulations.
To achieve BNG, a comprehensive understanding of the existing biodiversity baseline and its potential improvements is crucial. Traditionally, this process has involved extensive ecological surveys, making it time-consuming and expensive. However, as the legal obligations surrounding BNG increase, the need for efficient solutions has become evident.
In this article, we explore the concept of BNG, discuss the challenges associated with its implementation, and highlight the benefits of adopting a digital solution to bring BNG considerations into the forefront of infrastructure development. We will give focus to the BNG framework in England, given its relative maturity of development; a standardised methodology for implementing BNG analysis is currently in its fourth iteration.
Biodiversity net gain (BNG) is a strategy to develop land and contribute to the recovery of nature. It is a way of making sure the habitat for wildlife is in a better state than it was before development. Effectively it is a way to ensure that the biodiversity of the area of land or water impacted by a new development such as a transmission line is left in a better state than the baseline.
<aside> 💡 For reference CIEEM and IEMA define BNG as ‘development that leaves biodiversity in a better state than before and an approach where developers work with local governments, wildlife groups, landowners and other stakeholders in order to support their priorities for nature conservation’.
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<aside> 🌿 BNG is currently mandatory in England and Wales for all larger projects and for all projects from November 2023. Current legislation sets a requirement to increase biodiversity by a minimum of 10% compared to the existing baseline. Other jurisdictions such as the European Union and United States are progressing towards BNG requirements over the next 12-36 months.
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BNG is measured using what is called a 'Biodiversity Metric' calculator that was originally designed by Natural England. It uses changes in the extent and quality of habitats as a proxy for nature and compares the habitat found on a site before and after development. Four key factors underpin this comparison - habitat size, condition, distinctiveness and location. These factors are used to calculate the BNG baseline metric, which often interlinks with Environmental Impact Assessment (EIA) and planning processes.
In early stages of project development, infrastructure developers define route* options which tend to be at least several hundred metres in width. These routes capture areas that may be suitable for development of the infrastructure whilst providing flexibility for its final positioning, which often changes due to more detailed understanding and feedback as the development progresses. BNG is a key factor to consider when selecting routes because of its relation to impact on the local environment and high costs of mitigation measures.
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Using the current manual methods ecologists are sent out to explore every route analysed as the 'default' process. Ecologists will use a mix of satellite data and GIS layers but mostly field surveys to ascertain the biodiversity baseline of each route to establish what it is like 'pre construction'. As paying for ecologists to walk 5 x 10 km routes is time consuming and expensive, often assessing the biodiversity baseline is left until the end of the route optioneering process. This results in the BNG being carried out on the preferred alignment; there is usually minimal consideration of other potential routes.
