The mitigation hierarchy is a widely accepted concept used to manage biodiversity impacts. Abiding to the mitigation hierarchy is vital if developers hope to achieve biodiversity net gain. The approach consists of four steps: avoidance, minimisation, restoration and offsetting. Here’s a breakdown of each of the steps and how they can be applied in BNG assessments:
Avoidance
Avoidance is the first step of the mitigation hierarchy, and from the outset attempts to avoid negative impacts to biodiversity where possible. When considered within the early stages of a development, avoidance can be the most cost-effective way of reducing negative impacts to biodiversity. Avoidance can save developers money down the line that might have to be spent on compensating biodiversity loss.
In a BNG assessment, avoidance may result in developing on sites without rare habitats or a high biodiversity value, therefore minimising the development’s impact on biodiversity.
Minimisation
Minimisation aims to reduce the severity, duration or extent of negative impacts to biodiversity that cannot be avoided as a result of a development. Similarly to avoidance, it is recommended that minimisation is considered early on in project planning.
In a BNG assessment, minimisation could lead to adapting site layouts to avoid habitats of high biodiversity value. More general examples of minimisation include:
- Selection of construction materials;
- Use of machinery during development; and
- Pollution prevention measures.
Restoration
This step aims to restore habitats that may have lost biodiversity value as development impacts have not been able to be completely avoided or minimised. Restoration aims to return habitats to their original biodiversity value.
In a BNG assessment, this might lead to new areas of the habitat lost being created or enhancing existing ones. BNG requirements take this one step further and require a 10% net gain of biodiversity.
Offsetting
The final step of the mitigation hierarchy is to offset residual impacts that have been unable to be avoided, minimised or restored. Offsetting may occur on the development site or at a chosen offsetting site. In a BNG assessment this step can be implemented by creating new habitats or enhancing habitats at a chosen offsetting site. Offsetting is often an expensive and complex process and used as a last resort.
The mitigation hierarchy is not transferable to avoiding, minimising and compensating the loss of irreplaceable habitats. These impacts cannot be offset to achieve net gain.
How Can Acer Ecology Help with BNG?
Here at Acer Ecology we use the mitigation hierarchy to inform our biodiversity net gain assessments. We can help you by:
- calculating existing baseline biodiversity units at sites;
- advise on how to cost effectively increase biodiversity units at your site; and
- prepare long term management and monitoring plans for BNG.
Please contact us today to discuss your biodiversity net gain requirements.
