Invasive Non-Native Species management and Biodiversity Net Gain

Invasive non-native species (INNS) are one of the major causes of biodiversity loss and can have profound environmental, economic and social impacts. It is also a criminal offence to spread certain invasive non-native plants (external link) and animals (external link).

Managing INNS is a critical part of Local Nature Recovery Strategies (LNRS) and Biodiversity Net Gain (BNG). They offer significant opportunities to manage INNS for the benefit of biodiversity. On the other hand, improving habitat connectivity, particularly in the water environment, can inadvertently spread INNS further. It’s essential that work on habitats is undertaken in a biosecure manner and appropriate management ensures that it is the native species that benefit from the intervention.

What is Biodiversity Net Gain and how is it relevant to INNS?

Biodiversity Net Gain (BNG) is an approach to development, and/or land management, which aims to leave nature in a measurably better state than before the development takes place. This includes protecting existing habitats, improving connectivity and ensuring that lost or degraded habitats are compensated for by restoration, or by creating features that are of even greater value for nature. It does not change existing legal protections for important habitats and species.

Under the Environment Act 2021, all planning permissions granted in England (with a few exemptions) must deliver at least 10% BNG for major development and for small sites. BNG is measured using a statutory biodiversity metric and habitat management and monitoring to achieve target condition must be secured for at least 30 years. BNG will apply to Nationally Significant Infrastructure Projects at a later date.

The statutory biodiversity metric tool is used to calculate the biodiversity value of habitats with the project boundary to inform BNG. Within the tool, habitat condition (a measure of the habitat against its ecological optimum state) can either be negatively affected by the presence of INNS or positively influenced by reducing the presence of INNS. Strategic significance (the local significance of the habitat based on its location and the habitat type) is given higher value where targeted INNS action aligned with the relevant Local Nature Recovery Strategy will be achieved. And for watercourses, the physical presence of INNS is reflected in the encroachment scoring (where encroachment is described as any feature that adversely affects the natural function of the watercourse). The metric guidance also states that any high-risk INNS recorded through the condition assessments should be reported to the Local Biodiversity Records Centre and/or captured using a data app such as iRecord or INNSmapper.

How can BNG fund INNS management?

A network of Local Action Groups (LAGs) seeks to manage INNS that impact their communities and local environment. LAGs often use volunteers to manage INNS, providing social prescribing benefits and creating opportunities for residents to participate in the improvement of their environment. Many INNS management projects have suffered from short-term funding, resulting in the vestigial populations of INNS recolonising the site and providing only short-term benefits for the project.

BNG requires the management and monitoring of target habitats to be secured for at least 30 years. This has the potential to deliver a lasting legacy for biodiversity.

INNS considerations for project design and development

When developing strategies and projects it is essential that:

Any known records of INNS are reviewed and the risk for these INNS spreading further are considered. Sites should also be surveyed for unrecorded INNS, and site operators need to be able to recognise the INNS present. Plans should include provision to eradicate INNS to improve the quality of the habitat or prevent the population from spreading further.
Be aware that some INNS populations harbour diseases that can have a devastating impact on native communities. For instance, many urban lakes and ponds host exotic amphibians released from the pet trade that carry fungal diseases. Consider the disease risk from INNS, as well as the risk of INNS themselves.
Work should be undertaken in a biosecure manner. Landscaping and soil movement should consider the risk of spreading propagules. Staff, contractors and volunteers involved in the project should be made aware of the ‘check, clean, dry’ campaign and have access to biosecurity facilities such as washdown areas, pressure washers and boot cleaning stations.
Habitats that are in transition are particularly vulnerable to invasion. Provision must be made to respond rapidly and effectively to the appearance of INNS in restored or newly created habitats, modifying the BNG Habitat Management and Monitoring Plan (HMMP) in agreement with the Local Planning Authority as appropriate.
Completed schemes will require regular monitoring to ensure that INNS don’t establish. Project managers might consider using citizen science to monitor for potential future INNS and a legacy agreement with a local action group to eradicate new invasions, where possible. Any agreed approach should be detailed in the associated HMMP.

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Invasive Non-Native Species management and Biodiversity Net Gain