# Assessment of Ecosystem Services across the Land-Sea Interface in Baltic Case Studies
## 3 Results
### Ecosystem Services Potentials  
Resulting maps for ES potentials, based on the expert-based Baltic ESP Matrix (Table S1), are shown in Figure 3. ES potentials are shown on an aggregated level for each ES section. In addition, an overall habitat-weighted ES potential value was determined. It takes into account the proportional contribution of each habitat to the total area of each CSS. Besides the habitat-weighted ES potentials on an overall level (O), habitat-weighted ES potentials were also calculated separately for the terrestrial and marine area of each CSS. The habitat-weighted ES potential for terrestrial areas (T) is based on the proportional contribution of each terrestrial habitat to total terrestrial area of a CSS. Likewise, the habitat-weighted ES potential for marine areas (M) was calculated for each CSS. Figure 3: Ecosystem services (ES) potentials shown on an aggregated (averaged) level for provisioning, regulating and maintenance, and cultural ES. Lowest ES potentials are shown in red (<10) and highest potentials are shown in dark green (>90). Habitat-weighted ES potentials are indicated for each site for the overall areas (O), and for terrestrial (T) and marine (M) areas separately. General differences among the three ES sections can be observed, with increasing potentials from provisioning (PES O: 29 to 32), to regulating and maintenance (RES O: 40 to 44), to cultural ES (CES O: 52 to 61). This trend is shown for terrestrial as well as marine areas. However, differences in the relative increase between ES sections exist between land and sea. For terrestrial areas, the relative increase from provisioning to regulating ES is higher than the increase from regulating to cultural ES. In contrast, for marine areas it is reversed. This general trend can be explained by the inherent characteristics of the three ES sections. While provisioning ES, such as timber or crops, are often habitat-specific and spatially mutually exclusive, single habitats can have high potentials for multiple regulating ES. An example is the habitat type 'broad-leaved forest' (and other forest ecosystem types), which has very high potentials in the Baltic ESP Matrix (90) for the majority of regulating and maintenance ES, like groundwater recharge, and regulation of climate, air quality, erosion, and nutrients. Values for cultural ES potentials are often positively correlated. Natural habitats, such as coastal sandy beaches, reefs, rivers, lakes, and broad-leaved forests are considered to have high potentials for regional identity and natural heritage, which can also make them a hotspot for tourism and recreation. Differences between land and sea can be attributed to different characteristics of terrestrial and aquatic systems and their habitats. On land, ownerships are well defined, and the habitat types included in the CORINE classification largely reflect dominating land uses. Marine habitats are usually more natural and do not directly reflect human uses, as these are more variable in space and time. In addition, the three-dimensionality of aquatic systems enables a spatial and temporal co-existence of multiple uses. As a consequence, aggregated potentials for provisioning ES for marine areas are generally higher in comparison to terrestrial areas. Higher aggregated potentials for cultural ES can be ascribed to their higher degree of naturalness. Besides the general trends, differences among the three CSS can be observed. Indicated values for habitat-weighted ES potentials for provisioning ES are similar for the land-dominated system Schlei (PES-S O: 29; T: 27; M: 34) and the balanced system Greifswald Bay (PES-GWB O: 32; T: 26; M: 35). In comparison, the potential for provisioning ES for the terrestrial area of the sea-dominated system Curonian Lagoon, is much lower (PES-CL T: 18). In contrast, potentials for cultural ES are higher for the CSS Curonian Lagoon (CES-CL T: 67) compared to Schlei (CES-S T: 48) and Greifswald Bay (CES-GWB T: 52).