Net gain is a measurable, overall increase in biodiversity within a development or beyond its boundaries.

Existing regulations set out rules for mitigating unavoidable losses, and these will remain, but up until now these rules only served to minimise damage.  The concept of net gain is to exceed existing requirements, making new and better provision for key habitats and species.

Why net gain?

Here at The Wildlife Trusts, we’ve argued for net gain to be enshrined in planning rules for some time. Based on how the planning system has failed to deliver for wildlife so far, and the challenges ahead, measures like mandatory net gain are critical to secure nature’s recovery. 

As we’ve highlighted before, nature is in decline – and we know one of the key factors is poorly planned development, creating wildlife deserts and fragmenting our precious habitats.

We must move from simply trying to protect what’s left to creating more space for nature and creating the connections that can help wildlife recover and survive. This all the more pressing with an estimated 140,000 homes planned in the next twenty years, equivalent to building another Southampton within Hampshire and the Isle of Wight.

If done properly, new developments can also help to create wonderful places to live, where people are able to enjoy and connect with the natural world around them.

From farmland to wildflower haven

We’ve seen how it can work in practice at our Barton Meadows nature reserve near Winchester.  Over 30 hectares of wildlife-poor agricultural land has become a buzzing, flourishing wildflower haven thanks to our work with Winchester City Council planners dealing with Barton Farm development next door.

We know that there are enlightened housing developers who have been taking a lead in this area, but making this the norm could really help transform the fortunes of our local wildlife.

How net gain should work

The Wildlife Trusts will be formally responding to the government consultation in due course, but there are a few issues that leap out at us.

Firstly we’re glad to see measures set out to specifically secure biodiversity net gain, not just wider environmental benefits. It’s also important that these new standards are on top of existing rules like those set out in the Habitats Regulations. 

We’d been concerned that without clear rules, a developer could argue that the loss of ancient woodland could be compensated with, for example, green space created as residents’ gardens – though common sense and science both would rule that out as genuine net gain for our wildlife. 

We would like to see this accompanied by higher standards and smarter planning. For example new recreational green space (separate to areas that provide sanctuary for wildlife) and wildlife habitat like green corridors, green walls, and bird and bat boxes, must become the norm if we are to make our new communities less barren for wildlife.

And all development should be considered in the context of a national Nature Recovery Network, prioritising the protection of and investment in the key corridors between the wildlife-rich fragments we have left.

Importantly national rules would create a level playing field for developers across the country. Assuming that the government’s method for measuring biodiversity is effective and accurate, it would ensure that every developer is meeting scientifically-based standards – not just those who voluntarily play their part.

And any new planning rules should ensure that developers shouldn’t be able to pay for a license to harm nature.

Finally, biodiversity net gain should not only be embedded within local council’s plans and policies, but councils should also be given the support to enforce it too. Planners need the information and the resources to stand up for nature.

Next steps

Our experts will be crunching through the detail over the coming months, and will be submitting a formal response to the government in the new year.