Biodiversity Net Gain

Michael Mew, a Woodland Instead Director writes:

My knowledge of BNG was virtually non-existent just 9 months ago. I came across it on-line when researching the possibility of applying for grants to plant trees. My learning experience was steep enough to make me realise that it is not a subject that is easily explained. It is fairly technical, requires expert knowledge to enact and is largely hidden from public view. Yet it could become a model for other sectors. If you can convert species identification and mixes into a single number, there is a possibility you can do the same in other areas of life (e.g Social Net Gain?). I thought there was a need for a short, largely non-technical book to explain the whole policy to those not predisposed to read technical manuals. So the book “Learning to Read a Field” was born. This quote is from Chapter 1 – “What BNG Really Is”.

“At its simplest BNG is a requirement placed on development. When a developer builds on a site and reduces biodiversity, they must more than compensate for that loss. Sometimes they can do that on-site, often, they cannot. When they cannot, they must look elsewhere.

This is where something important happens. A regulatory requirement creates a demand.

That demand is straightforward. Developers need to source biodiversity units. The upgrading of biodiversity on the development site, plus the extra 10%, is not an optional enhancement, it is a condition of planning.

This creates a position where biodiversity is no longer just an environmental consideration, but a business necessity. Where can we get the required units and how much do we have to pay? In other words, it becomes a necessary input into development planning. And once something becomes necessary, it acquires value. Where there is demand and value attached, supply surely follows. Landowners can meet that demand by creating supply. They do so not by selling land, but by changing it. They enhance habitats and improve ecological condition thereby increasing measurable biodiversity value.”

Recent changes to the BNG policy have served to address some structural problems. Developers have, where possible, to produce the 10% uplift to biodiversity on the same site they are developing. But imagine a developer building houses on a field. There is often a minimum density to housing that they have to meet, so leaving a section of the site for BNG is usually not possible. Once houses, driveways, and roads are built, there is little area left to produce the 110% of the original biodiversity for the whole site. Quite often, either the on-site uplift tends to be in small piecemeal areas which are hard to monitor or the developer pays for units from an offsite project, such as ours, that is set up specifically to produce BNG units for sale. The purchase of units from offsite “BNG Banks” is often the easiest solution for all concerned because the Developer generally does not want to run a biodiversity project and the regulators find it easier to follow progress on one larger site rather than a list of scattered smaller areas.

One aspect that is not obvious is just how biodiversity, that after all reflects a variable set of physical species in a variable environment, is transformed into a “unit” that can be traded and sold. Whilst “Learning to Read a Field” walks the reader through the Metric spreadsheet step by step, it is sufficiently obscure to most people to promote distrust, particularly as the actors in the use of the system, according to a recent academic work, are themselves largely distrusted.

In very simple terms, an expert ecologist assesses your land and inputs the ecological values he assesses into the Metric spreadsheet to obtain a Baseline Unit count. He or another expert decides what uplift of biodiversity would be created by your project. These. theoretical values are then run through the Metric spreadsheet again to give a target “after” result. The difference between the before and after numbers gives you a number of units you are going to have for sale. This is a very simplified overview of how the system works, but it has many wrinkles that are explored in the book.

It should also be noted that BNG is only one of a number of eco restoration possibilities, many of which can attract grants. The Isle of Wight Biosphere has a particularly large number of granting bodies.