Assessment of ecosystem services across the land–sea interface in Baltic case studies

Spatial assessments of ecosystem services (ES) are needed to fulfil EU policy requirements and to support practical applications of the ES concept in policy implementation. So far, ES assessments have largely focused on terrestrial systems. A joint approach for land and sea is especially lacking. To overcome this gap, we present a novel spatial habitat typology and ES classification for an assessment across the land–sea interface. We build upon existing approaches and common spatial definitions, like CORINE land cover (CLC) types, water bodies of the Water Framework Directive (WFD), and habitat types according to the Habitats Directive (HD). We show applications of the resulting ES matrix for an expert-based assessment of ES potentials in three Baltic study sites (Schlei, Greifswald Bay and Curonian Lagoon). A complementary indicator-based approach to assess ES flows is introduced and applied. It enables a quantification of ES potentials and flows and ensures comparability among case study sites. Comparisons between the results for ES potentials and flows show that development capacities exist in particular for provisioning ES for marine habitats. Our approaches are spatially expandable and transferrable and could be applied to support environmental policy implementation. Further, we discuss their practical relevance, current limitations, and future research perspectives