Preliminary Ecological Appraisal

A Preliminary Ecological Appraisal (PEA) is normally, as the name suggests, the first stage in any site assessment.

A PEA has two main elements: an ecological desk study and an extended Phase 1 habitat survey.

Ecological desk study

At Thomson, when undertaking the desk study, we collate data on statutory designated sites (legally protected), such as Sites of Special Scientific Interest, and priority habitats. We also contact the local biological records centre to obtain details of locally designated sites for wildlife and existing records of protected and priority species in the vicinity of the site. The data from these and other sources is brought together using GIS to provide either a printed map or an interactive map.

Extended Phase 1 habitat survey

Using the extended Phase 1 habitat survey technique (JNCC, 2010; IEA, 1995), we map the habitats present on the site and, if required, the surrounding area. For each habitat area, we record the plant species present and their abundance. We also assess the potential of the site for protected and priority species, and record any evidence of these that we find during the survey, such as badger setts.

As part of the PEA, we are able to advise on any initial ecological issues that we identify, for example, in relation to designated sites and priority habitats, and also what is likely to be required in order to complete the ecological assessment, for example, surveys for protected species. Initial guidance on measures that could be incorporated into the development design to avoid and mitigate ecological impacts can also be provided at this stage. The PEA can therefore be an extremely useful tool for development masterplanning and can also form the basis of an ecological impact assessment later on in the project.

The PEA is a vital first stage in the assessment process and is best undertaken by experienced staff so that key issues are identified and the scope of further work is balanced. All our surveyors are members of the Chartered Institute of Ecology and Environmental Management and meet the competency standards for PEA provided by this organisation.

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Further reading and related articles

Case Study

Ecology services, South Wales Valley Lines Electrification Scheme

  • Ecology
  • Rail