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Biodiversity net gain

What is biodiversity and why do we need it? 

Biodiversity is the name we give to the variety and the amount of all life on Earth, this includes plants, animals, bacteria and fungi.  For our planet to stay healthy we need a large variety of plants and animals.  Without this we will not have the healthy ecosystems that we rely on to provide the air we breathe and the food we eat.  Nature also plays a critical role in how we mitigate and adapt to climate change, and in supporting our mental and physical wellbeing.

Watch this short video from the Natural History Museum to learn more about biodiversity on YouTube and why we need it.

Why is it in decline? 

Like the rest of the country, biodiversity in Dorset is in rapid decline.   Over 400 land and freshwater species recorded in Dorset in the past are now thought to be extinct.  Activities like building, pollution, industrial farming and forestry, and climate change have all contributed to this loss of wildlife in our county.   

What is biodiversity net gain? 

Biodiversity net gain (BNG) is an approach to development that aims to leave the natural environment in a measurably better state than it was beforehand, and forms part of the Environment Act 2021.    

In 2024 it became mandatory in England and developers are now required to deliver a biodiversity net gain of at least 10%. This means developments need to result in more or better-quality natural habitat than there was before development. For a simple overview, watch Natural England's Introduction to Biodiversity Net Gain on YouTube.

Infographic showing biodiversity net loss and net gain in developments

Who does it affect? 

Biodiversity net gain will apply to all development that falls under the Town and County Planning Act 1990, with some exceptions such as permitted development and householder applications.  And will impact on all aspects of planning and place making. 

The individuals and groups which will be most impacted and will need to understand the requirements of biodiversity net gain are:  

  • developers  
  • local planning authority  
  • land managers wanting to sell in the biodiversity net gain market 

What is Dorset Council’s role? 

As a local planning authority, Dorset Council will need to make sure developers and land managers meet the requirements for biodiversity net gain. 

We will be responsible for:  

  • setting local policies and strategies to support biodiversity net gain  
  • approving and reviewing planning applications and biodiversity gain plans 
  • checking biodiversity metric calculations 
  • checking habitat surveys 
  • checking developers selling excess on-site gains 
  • checking the biodiversity gain sites register for off-site gains 
  • secure gains with a legal agreement
  • monitoring biodiversity net gain 
  • working with developers who wish to buy biodiversity net gain credits   

We strongly advise anyone making a planning application to consider their biodiversity net gain strategy at the earliest opportunity (ideally before the application is submitted) to avoid delays during the planning application process, including at determination and approval of the biodiversity net gain measures. 

For more information on biodiversity net gain within the Dorset Council area and what we will expect from planning applications, please read our Biodiversity Net Gain: Guidance for Applicants and Agents.

Where can I find out more about biodiversity net gain? 

The government has produced Planning Practice Guidance (to interpret and add to the legislation) and more general guidance on biodiversity net gain.  It has also provided the below step-by-step guidance: 

When will biodiversity net gain be required? 

From 12 February 2024 a mandatory requirement to provide a minimum 10% BNG will apply to all applications for major development.  Major development includes residential developments with 10 or more dwellings, or where the site area is greater than 0.5 hectares.

From 2 April 2024 this requirement will extend to include applications for small sites. Small sites include residential development where the number of dwellings is between 1 and 9, or if unknown the site area is less than 0.5 hectares. Commercial development where floor space created is less than 1,000 square metres or the total site area is less than 1 hectare.

You can find out more about biodiversity net gain requirements for Dorset in the ‘local list’ section of our validation checklist.

Applicants are strongly encouraged to use our pre-application advice on biodiversity net gain service to avoid delays through the planning process.

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