Aylesbury Vale Area

Biodiversity Accounting Supplementary Planning Document

Ended on the 19 March 2021
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1.0 The Aim of this Supplementary Planning Document

Biological Diversity, more commonly known as Biodiversity is the term given to "… the variety of life on Earth and the natural patterns it forms. The biodiversity we see today is the fruit of billions of years of evolution, shaped by natural processes and, increasingly, by the influence of humans. It forms the web of life of which we are an integral part and upon which we so fully depend" (Convention on Biological Diversity).

1.1 Whilst biodiversity has an intrinsic value, it also delivers essential human services, such as food production, climate change adaptation, flood regulation, crop pollination plus numerous other benefits including enhancing human mental and physical well-being. Developments, no matter how small, can provide additional biodiversity which can help link to other biologically diverse developments; providing stepping stones of genetic diversity across Buckinghamshire's landscapes and beyond.

1.2 State of Nature Reports document a steady decline in biodiversity within the UK. In response, the UK Government is mandating Biodiversity Net Gain to ensure that development enhances biodiversity and delivers thriving natural spaces for communities. Biodiversity Net Gain is an approach that 'leaves biodiversity in a better state than before' (Chartered Institute of Ecology and Environmental Management).

1.3 This guidance, produced with advice from the Buckinghamshire and Milton Keynes Natural Environment Partnership, sets out how Biodiversity Accounting will be used to achieve Biodiversity Net Gain across Buckinghamshire. It sets out how the council and those making planning applications will calculate the development impacts on biodiversity as part of their landscape plans and enables schemes to be devised to ensure that a net gain in biodiversity is delivered on site.

1.4 Achieving success in Biodiversity Net Gain requires compliance with the council's mitigation hierarchy. This hierarchy is firstly to avoid loss of biodiversity on-site, then to mitigate if loss is necessary, next to ensure any compensation for loss takes place on–site and finally only off-site as a last option. Following the hierarchy means that genuine attempts must be made on-site to reduce impacts on biodiversity as a result of development.

1.5 The requirements for a net gain in biodiversity do not undermine the existing range of protections outlined in planning policy and legislation for protected sites or for irreplaceable habitats. Accounting for biodiversity also does not replace the existing planning application requirements for ecological assessment and species surveys.

In summary, this supplementary planning document covers two key areas:

  1.  Biodiversity Accounting: What it is, and how the biodiversity value of habitats can be measured before, during and after a development.
  2.  Biodiversity Compensation: What should be done if there is a loss to the biodiversity value of habitats as a result of a development.
This is illustrated in Exemplification 1 below.


Exemplification 1: Components of the mitigation hierarchy.

mitigation hierarchy

Source: Adapted from the Mitigation Hierarchy Guide

Mitigation Hierachy

  1.  is the potential negative impact of the proposed scheme on biodiversity;
  2.  is the implementation of the mitigation hierarchy - without net gain, leaving residual impacts on-site;
  3.  illustrates how net gain can be achieved through on-site design changes; with less of a residual impact on site; and with offsets employed to ensure a net gain overall – only after the full implementation of the mitigation hierachy on-site.


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