Assessing and valuing the recreational ecosystem services of Germany's national parks using travel cost models

This paper estimates the recreational ecosystem services (RES) of 15 German national parks (NLP) in one of the most comprehensive RES valuations of NLP systems performed to date. The RES were evaluated using zonal travel cost models (TCM) based on 24,548 representative interviews conducted with a uniform methodology between 2004 and 2015. Reaction functions were estimated for each park as double-log regression models. The lower-limit consumer surplus of recreation in German NLP totals EUR 385.3-621.8 million (including only visitors whose trip decisions were influenced by the parks' protected status), while an upper-limit value reached EUR 1.690-2.751 billion (including all visitors). Thus, NLP generate enormous non-monetary values for German society. The standardized approach applied could be used to harmonize assessments and valuations of RES in protected areas. Finally, the article advances the theory of RES assessment, valuation and mapping by highlighting the importance of on-site visitation data. RES do not exist a priori, but emerge as co-products of ecosystems and visitors' perceptions and valuations. For this reason, we discourage the use of context-specific RES results in benefit transfer approaches.