TESSA (Toolkit for Ecosystem Service Site-based Assessment)


The TESSA toolkit is an easy-to-use workbook that leads the user through the steps needed to assess the ecosystem services provided at a particular site. It is built around a comparison of the site in two alternative states, e.g. before and after restoration or conversion, and encourages a high level of stakeholder engagement. The toolkit was initially developed for conservation practitioners but can be used by anyone, including the private sector and those with no prior knowledge of ecosystem services. It includes an introduction to the concepts of ecosystem services and natural capital, guidance on how to conduct a preliminary scoping appraisal to identify important services and beneficiaries, decision trees to identify the best methods to use for each service, and links to a set of simple low-cost methods for measuring ecosystem services either qualitatively or quantitatively. Worked examples are provided, as well as instructions for collecting site-specific data where appropriate (including field surveys and stakeholder input). There is also guidance on how to communicate results to decision-makers.


Data gathered by the user for the site being assessed.

Quantitative data on ecosystem services
Tables / statistics / reports
Economic assessment
Cost-benefit assessment
Site scale
Local scale
Cost of the tool (and guidance): 
Open access (free)
The tool is not constrained to specific land use types. TESSA is adaptable to each local situation. TESSA does not offer at the moment application for offshore marine ecosystems. It covers coastal protection but this relates mostly to saltmarshes, mudflats and mangrove habitats. Built around a comparison of two alternative states of the site, e.g. before and after restoration or degradation.
Resource requirement (software): 
Adobe acrobat to read the interactive pdf, plus 184 MB storage space.
Level of technical expertise required: 
Internet use skills
Types of ecosystem service included: 
Habitat type (UK NEA habitats): 
Mountains, moors and heaths
Semi-natural grasslands
Enclosed farmland
Freshwater, wetlands and floodplains
Coastal margins
How does it work?: 

The toolkit is based on an interactive pdf document which leads the user through a step by step approach to assess the main ecosystem services provided by the site under consideration (typically 100 – 100,000 ha). Preliminary guidance helps the user to select a suitable site, define the exact questions to be addressed (e.g., threats, pressures, drivers of change; what to implement), engage the relevant stakeholders and find out about the local political, environmental and socio-economic context. The first step is then a scoping appraisal to identify which are the most important services provided by the site. For each of these services, there is a choice of several assessment methods, including manual calculations using published data, stakeholder mapping, field surveys or modelling tools (options include use of the WaterWorld and Co$tingNature models). A decision tree for each service assessment helps the user to choose the most suitable method, given the available data and resources. Electronic links take the user to separate short pdfs which describe how to apply each method, and there are also links to additional guidance documents and case studies.

Where can I get it?: