Invasive species identification should be undertaken by an appropriately qualified and experienced person. The identification survey should aim to determine the following with regards to invasive species:
- The type of invasive species present, and the extent of their presence;
- The extent of any habitat suitable to support Invasive Species;
- Any constraints to treatment, including the client’s expectations with respect to timescale and development plans, and the presence of potentially sensitive receptors.
The key aim of the identification survey is to provide sufficient information from which a specialist can design and propose a treatment programme.
Pre-Site Walkover Desk-top Review
Before undertaking a walkover of a site, it is useful to review aerial photographs of the site and surrounding area, and available information on the local area, in order to identify likely features warranting specific consideration, including:
- Linear features such as railway lines, rivers or canals which may act as a route for invasive species transfer;
- The presence of watercourses or other habitats which may support invasive species;
- The proximity of the Site to residential gardens or allotments;
- Former land use.
Preparation for the Walkover
All available desk-top information should be utilised to develop a site specific health and safety plan with appropriate risk assessments.
Performing the Walkover
During the walkover the surveyor will identify and maps the habitats on the site and on adjoining land, where access permits, and checks them for the presence of invasive non-native species.
During the survey, the occurrence of any terrestrial invasive weeds on the site must be identified and recorded in terms of species present and stand size, including growth stage of the weeds. In addition, any notable features that may impact upon treatment methodology should be recorded, for example the proximity of a water body to the invasive weeds.
Any signs of other invasive species must also be recorded, and photographed where possible. This includes invasive aquatic weeds where a water body is present at or adjacent to the site, and terrestrial and aquatic fauna.
The findings of the identification survey should be reported in an invasive species identification report, and should include as a minimum the following information:
- Plans and photographs illustrating the habitats on the site and the location and extent of any suspected or confirmed invasive species.
- Any constraints which limited the extent or performance of the survey.
- The location of any sensitive receptors which may impact treatment methodologies.
- Recommendations for any further species specific surveys, if required.