What impacts ecosystem services in tropical coastal tourism cities? A comparative case study of Haikou and Sanya, China.

The ecological environment of tourism-oriented towns is attracting increasing attention. Taking the cities of Haikou and Sanya as examples, we examined changes in six ecosystem services (ES), including water conservation (WC), crop production (CP), soil retention (SR), carbon storage (CS), habitat quality (HQ), and tourism recreation (TR) from 2005 to 2020. From the three perspectives of geographical environment, socioeconomic development, and tourism development force, 14 indicators were chosen to examine the impact on ES. Except for Haikou's TR, the other ES of Haikou and Sanya showed a decreasing trend from 2005 to 2020. The values of six ES were lower in coastal zones than in noncoastal zones, which were more obvious in Sanya. Specifically, the areas of low value in Sanya were concentrated in the coastal region, and the areas with low value in Haikou were primarily distributed in blocks along the coast and in bands or points in the central and southern areas. From the perspective of influencing factors, the natural environmental factors dominate in Haikou, followed by the socio-economic factors and finally the tourism development factors, while the natural environmental factors also dominate in Sanya, followed by the tourism development factors and finally the socio-economic factors. We provided recommendations for sustainable tourism development in Haikou and Sanya. This study has significant implications for both integrated management and scientific decision-making to enhance the ES of tourism destinations.