Spatial Ecosystem Service Assessment Across the Land–Sea Interface

Various approaches to map and assess ecosystem services (ES) have emerged in the past decades. Yet, they are still mainly focused on terrestrial systems and comparable methods for marine systems are lagging behind. We present a joint spatial typology and ES classification for the German Baltic Sea to enable an ES assessment across the land–sea interface. Together, they built the basis for an expert-based assessment of ES potentials, and resulted in the first German Baltic Ecosystem Service Potential Matrix (Baltic ESP Matrix). We show its application for a spatial ES mapping across land and sea. Further, a complementary approach for an assessment along the direct coastline (i.e. where the water meets land) is presented. Systematic differences between terrestrial and marine systems, such as spatial and temporal variability of habitats, distinctness of boundaries and the 3-dimensional characteristic of aquatic systems, limit the comparability between both systems. In addition, subjectivity of experts resulting from differing knowledge, experiences, perceptions and traditions leads to dissimilar assessments of ES potentials at land and sea and affect experts’ scores. To increase reliability of expert-based assessments, benchmark systems based on reference habitats could be used.