PEA Assessment Consultants | Ecological Desk Studies & Surveys

Preliminary ecological appraisals are usually required during the planning process to enable a development to be approved. A PEA allows our expert team to evaluate a site and make recommendations where necessary for you to maintain ecological compliance.

Our expertise

Thomson EC’s specialists can help with all aspects of a Preliminary Ecological Appraisal (PEA). Established for over 20 years, we are well-placed to identify key issues and the scope of further work required to move forward with your development. We are Chartered Institute of Ecology and Environmental Management registered practice, and our surveyors meet the competency standards for PEA provided by this organisation.

What is a Preliminary Ecological Appraisal?

A Preliminary Ecological Appraisal is normally, as the name suggests, the first stage in any site assessment. A PEA has two main elements: an ecological desk study and a UK Habitat Classification Survey, which is extended to include an assessment for the habitat to support protected species.

Our Preliminary Ecological Appraisal Services

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 are brought together using GIS to provide either a digitised map of the site and nearby constraints.

Habitat Survey

What our survey involves

Site visit to map the habitat types present and their condition
Record plant species present (and relative abundance)
Assess the potential of the site for protected and priority species
Record any evidence of protected and priority species
Advise on initial ecological issues highlighted and requirements for further assessment where necessary.
Guidance on measures to avoid and mitigate ecological impact.

Using the UK Habitat Classification (UKHab)

(JNCC, 2010), 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, and make an assessment of the condition of each habitat parcel.. 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, for example signs of badger activity..

As part of the PEA, we are able to advise on initial ecological issues that we identify, for example, in relation to designated sites and priority habitats. We also advise on what is likely to be required in order to complete the ecological assessment, such as 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 master planning and can also form the basis of an Ecological Impact Assessment (EcIA) later in the project.

“Working collaboratively with Thomson, we were able to provide our client with a complete service including ecology surveys and reports as well as the practical vegetation management and invasive species remediation works.” Project manager, Ecological mitigation works, Intercity Express Programme

You can visit our recent projects here to find out more about our work.

Frequently asked questions

When can preliminary ecological appraisal services take place?

A PEA should be undertaken as early as possible in the planning process. PEAs can be undertaken all year round, however, the optimal period is between April and September. If they occur outside this period, there may be seasonal constraints and additional surveys may be required.

Why are PEAs important?

They help identify potential risks before a project moves too far ahead. By understanding what wildlife and habitats may be affected, developers can plan the next steps properly and avoid unnecessary delays. For many schemes, a PEA sets the foundation for the whole ecological strategy.

When should a PEA be arranged?

It’s sensible to carry out a PEA as soon as a site is being considered for development. Early surveys mean there is more time to deal with any issues, particularly if further species-specific surveys are likely to be needed and have restricted seasonal windows.

What does a PEA include?

A typical PEA combines two parts, including an ecological desk study and a habitat survey. The desk study gathers existing records of protected species and designated sites, while the site visit allows the ecologist to map habitats and assess the potential for notable wildlife. Next, the findings are set out in a report with clear recommendations.

How long does the PEA process take?

Most site visits take around a day, depending on the size and complexity of the land. Reports are usually delivered within two to three weeks, although timings can vary slightly depending on the availability of local records and the level of detail required.