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What Is Biodiversity Net Gain (BNG)?

Biodiversity Net Gain (BNG) has quickly become one of the most talked-about changes in the planning system. Developers are expected to deliver it. Landowners are being approached about it. Ecologists are preparing plans around it.

But what does it actually mean?

At its heart, Biodiversity Net Gain is a simple idea: development should leave nature in a better state than it found it.

For decades, new development often came at the expense of wildlife and habitats. Hedgerows disappeared, grasslands were lost and ecological networks became increasingly fragmented. Biodiversity Net Gain was introduced to change that conversation. Rather than accepting environmental loss as an unavoidable consequence of growth, it asks a different question:

How can development actively contribute to nature’s recovery?

Introduced through the Environment Act 2021 and mandatory for most developments in England from 2024, BNG requires developers to deliver measurable improvements in biodiversity alongside their schemes.

 

The 10% Rule Explained

Most qualifying developments must achieve at least a 10% increase in biodiversity compared with the condition of the site before development began.

That uplift isn’t based on guesswork. It’s calculated using the statutory biodiversity metric, which considers factors such as habitat type, condition and distinctiveness to determine whether a development delivers genuine ecological improvements.

The resulting enhancements must then be secured and maintained for a minimum of 30 years.

In other words, Biodiversity Net Gain isn’t simply a box to tick at planning stage. It’s a long-term commitment.

How Is Biodiversity Net Gain Delivered?

Ideally, the required uplift is achieved within the development site itself.

Perhaps new habitats are created. Existing habitats are enhanced. Wildlife corridors are restored.

In reality, however, space is often limited. Urban developments may not have enough land to accommodate the biodiversity improvements required to meet the 10% target.

When that happens, developers can secure off-site Biodiversity Net Gain units from landowners who are creating or enhancing habitats elsewhere.

This is where Biodiversity Net Gain begins to extend beyond the red line boundary of a development site and into a much broader story of landscape recovery.

Where Do Landowners Fit In?

For some landowners, Biodiversity Net Gain presents an opportunity to diversify how land is managed and generate income from environmental enhancement.

Habitats can be restored, expanded or created to generate Biodiversity Net Gain units that may then be sold to developers needing off-site solutions.

However, these arrangements come with responsibilities.

The biodiversity gains promised cannot simply be delivered and forgotten. They must be maintained, monitored and protected over the long term.

That commitment lasts for at least 30 years.

What Is a Conservation Covenant?

One way of securing those long-term commitments is through a Conservation Covenant.

A Conservation Covenant is a voluntary but legally binding agreement between a landowner and a Responsible Body. It sets out the conservation objectives for the land, establishes what activities can and cannot take place, and provides a framework for ensuring the agreed environmental outcomes are achieved.

The purpose is simple: to give confidence that the habitats being created today will continue to deliver meaningful benefits for nature long into the future.

So, What Does a Responsible Body Do?

This is where organisations such as ProHort EcoShield come in.

As a DEFRA approved Responsible Body, ProHort EcoShield works with landowners to establish Conservation Covenants and oversee the stewardship arrangements that sit behind them.

We help define the outcomes that need to be achieved, support the implementation of agreed management measures and monitor progress throughout the lifetime of the covenant.

In many ways, Responsible Bodies provide the continuity that Biodiversity Net Gain depends upon. Planning permission may mark the beginning of the journey, but long-term stewardship is what turns good intentions into lasting environmental outcomes.

Why Does Biodiversity Net Gain Matter?

Biodiversity Net Gain isn’t just a planning requirement.

It’s a recognition that development and environmental recovery don’t have to exist in opposition to one another.

When delivered well, BNG can reconnect fragmented habitats, strengthen ecological resilience, improve landscapes and contribute to wider nature recovery ambitions across England.

It challenges us to think beyond the lifetime of a construction project and consider the legacy we leave behind.

After all, creating places for people should also mean creating space for nature to thrive.

If you’d like to understand more about Responsible Bodies, Conservation Covenants or the long-term stewardship behind Biodiversity Net Gain, ProHort EcoShield can help you navigate the process with confidence.

Frequently Asked Questions

What is Biodiversity Net Gain (BNG)?