Ecological Constraints Assessment

Preliminary Ecological Appraisals are required by the National Planning Policy Framework (NPPF), which sets out the Government’s planning policies for England and how these are expected to be applied.

With regards to conserving and enhancing the natural environment the NPPF states that “The planning system should contribute to and enhance the natural and local environment by […] minimising impacts on biodiversity and providing net gains in biodiversity where possible, […]”. One of the core planning principles of the NPPF is that planning should “contribute to conserving and enhancing the natural environment”.

Many terms are used to describe Preliminary Ecological Appraisals (see guidelines) such as: Baseline Ecological Survey, Ecological Site Assessment, Ecological Site Appraisal, Ecological Scoping Survey, Ecological Site Walkover Survey, or, Variations on Phase 1 or Extended Phase 1 Habitat Survey or Constraints Survey.

Ecological Constraints Assessment or Extended Phase 1 Habitat Survey?

REC provide two levels of Preliminary Ecological Appraisal:

  • Ecological Constraints Assessment, which is generally suitable for development sites of limited ecological potential, and
  • Extended Phase 1 Habitat Survey, which is suitable for all development types

Both surveys are designed to identify:

  • The major habitats present on site
  • The potential for legally protected species to be present
  • Additional ecological surveys likely to be required
  • The potential impacts of a development
  • The legal and planning policy issues that may need to be addressed

However, the level of detail is different for both and these differences are defined within the below table:


Type of Survey

  • A preliminary desk study consists of a database search of government funded websites, Ordnance Survey mapping and aerial photography to identify statutory designated sites, records of legally protected species and features of interest within the site and within a 1 km radius around the site boundary
  • A detailed desk study involves an in-depth consultation with the relevant local biodiversity records centre, which charges a fee for additional information such as non-statutory designated sites and accurate records of legally protected species
  • A site survey comprises a walkover of the site by a competent ecologist to record all habitats present and note features of particular interest following guidance stipulated in the Handbook for Phase 1 habitat survey (JNCC, 2010). This is necessary to determine whether any further surveys are necessary in order to comply with the guidelines that the local planning authority will follow when deciding upon a planning application
  • A report collates the results of the desk based study and the site survey into an appropriately detailed document that is suitable for submission with a planning application to the local planning authority
  • An impact assessment determines the nature (i.e. positive or negative) and magnitude (i.e. low, medium or high) of the effect that the proposals may have on the site’s biodiversity. It informs the requirement for mitigation, compensation and enhancement as well as any additional surveys
  • Further surveys may be required if the impact assessment determines a negative effect on legally protected species. The surveys will inform the necessary level of mitigation, compensation and enhancements that will be accepted by the local planning authority
  • Mitigation aims to reduce a negative effect on biodiversity. Compensation is required when an impact cannot be mitigated and a certain habitat is replaced or restored. Enhancements intend to increase the site’s biodiversity and reinforce the ecological credentials of the planning application

Survey Timings

REC always has your needs and budget in mind. We provide professional advice from an early stage to ensure the risk of any adverse effects is avoided or significantly minimised with the aim to avoid costly mitigation and compensation measures.

The surveys can be carried out at any time of the year, although spring or summer surveys allow for easier vegetation identification. Survey timings are crucial in order to obtain reliable data and prevent project delay as consents and licenses may be required for any mitigation procedures.

For further information or advice please contact your local office or contact us online.

Ecology Services