In the context of impact assessments, we consider those ecosystem services to be soil related that are either based exclusively on soil functions (i.e. purification of water during its passage through the soil matrix), or where soil functions make a significant contribution to the final service (i.e. aboveground habitats created by plants growing in the soil.). Both types of soil related ecosystem services have in common that they are affected by agricultural management.
Impact assessments need to account for the fact that agricultural management always implies trade-offs between different ecosystem services. Each management option will enhance the provision of some ecosystem services while reducing the provision of others. Where impact assessments only consider a selected number of services, this selection may therefore already determine the assessment results. Depending on which ecosystem services are considered, assessments will find different policy options to have the most positive impacts. Sound research design is required to safeguard against such arbitrariness and potential for manipulation (see section on Impact Area Selection), and to instead highlight the trade-offs between options.
For the assessment of ecosystem services, the BonaRes Assessment Platform uses the Common International Classification of Ecosystem Services (CICES) (Haines-Young & Potschin, 2018) which provides a complete and standardized classification scheme designed to support accounting of ecosystem services. CICES has a strictly hierarchical, five-level structure, organized from bottom to top into: section, division, group, class and class type. Three sections provided by the biotic components of ecosystems are distinguished: Provisioning, Regulation & Maintenance and Cultural. In an extension introduced in 2018 with CICES version 5.1, abiotic sections for Provisioning, Regulation & Maintenance and Cultural services were added. Figure 11 shows how the production of cereals as food crops fits into the CICES hierarchy.
