Skip to Content


Toolkit for Ecosystem Service
Site-Based Assessment

Understanding the impacts on natural capital and ecosystem services of actual and potential changes in state at individual sites is important for promoting better planning decisions to support both biodiversity conservation and ecosystem service delivery. This approach has been relatively little used because it has been assumed that ecosystem services are technically difficult and expensive to measure.

This toolkit is designed to overcome this obstacle by providing practical guidance on how to identify which services may be significant at a site of interest, what data are needed to measure them, what methods or sources can be used to obtain the data and how to communicate the results.

The toolkit emphasizes the importance of comparing estimates for alternative states of a site (for example, before and after conversion to agriculture) so that decision-makers can assess the net consequences of such a change, and hence the benefits for human well-being that may be lost through the change or gained by conservation.

The toolkit has attempted to find a balance between simplicity and utility of developing convincing information for decision-makers and therefore excludes consideration of some of the more advanced concepts in ecosystem services. This is so that it can be used by non-experts, yet still provide scientifically robust information.

TESSA: A tool to assess the benefits of nature

Request form

To request a copy of the toolkit, please fill in the following details. The information you provide will help the toolkit compilers to understand how it is being used and by whom and where, in order to shape its further development.

  • Terms of use

  • This field is for validation purposes and should be left unchanged.

The Toolkit for Ecosystem Service Site-based Assessment (TESSA) has been compiled by the following organisations:

The development of TESSA was supported by the following organisations:

Terms and conditions

  1. A copy of any publically available materials or publications derived in part or in whole from the use of TESSA should be sent to [email protected], and should provide appropriate acknowledgement and use the citation below:

    Peh, K. S.-H., Balmford, A. P., Bradbury, R. B., Brown, C., Butchart, S. H. M., Hughes, F. M. R., MacDonald, M. A, Stattersfield, A. J., Thomas, D. H. L., Trevelyan, R. J., Walpole, M. & Merriman, J. C. (2017) Toolkit for Ecosystem Service Site-based Assessment (TESSA). Version 2.0 Cambridge, UK. Available at:
  2. Reproduction of TESSA or products derived from it, either whole or in part, for commercial purposes is prohibited without prior written permission. This includes a) any use by, on behalf of, or to inform or assist the activities of, a commercial entity (an entity that operates ‘for profit’) or b) use by any non-profit entity for the purposes of revenue generation. To request permission please provide details of the organisation and type of commercial use at [email protected]
  3. The recipient will only use TESSA for the purpose for which it was requested, if subsequent or different use is required the recipient must register a new request at This allows new users to access the latest version and most updated content of TESSA.
  4. The recipient will not pass TESSA on to third parties and will direct all third-party requests to
  5. The recipient will not publish TESSA, either whole or in part, on a website, FTP site, CD, memory stick or any other media. The recipient should provide a link, where appropriate, to
  6. Use of TESSA does not constitute endorsement of any derived products, reports or analyses by any of the organisations involved in its compilation (see list above). The logos of these organisations must not be used on any derived products, reports or analyses, or supporting materials, without express permission.
  7. The compilers of TESSA reserve the right to comment on the accuracy of representation of the data in material produced by a recipient.


The compilers of TESSA make no warranties or representations, express or implied, regarding the use of TESSA by other individuals or organisations. Neither the individual staff/organisations nor their affiliated or related entities shall be responsible or liable to any person, firm or corporation for any loss, damage, injury, claim or liability of any kind or character based on or resulting from any information contained in the TESSA. TESSA may be updated or changed at any time without notice; however, no commitment is made for such updating.

Errors and omissions

Suggestions for improvement or notification of errors or omissions are welcomed, so that they can be considered in future versions. Please email [email protected]