Monitoring changes and multi-scenario simulations of land use and ecosystem service values in coastal cities: A case study of Qingdao, China

The study of land cover dynamics and the valuation of ecosystem services in coastal cities is pivotal for guiding sustainable urban development and conserving natural resources amidst the unique challenges posed by their geographical and ecological contexts. This study utilizes a 30 m x 30 m land use/cover change (LUCC) dataset to elucidate the spatiotemporal evolution of LUCC and ecosystem service value (ESV) and the trade-offs and synergistic relationships among ecosystem services in the coastal city of Qingdao under three different scenarios over the past 35 years and in the future based on the dual perspective of the past-future by using the equivalent factor approach (EFA), the PLUS model, and Spearman's rank correlation coefficient. The findings reveal a pronounced expansion in built-up areas in Qingdao from 1985 to 2020, with a concomitant significant reduction in cropland, leading to a fluctuation in the total ESV, which initially increased and then declined. This indicates the intense pressure Qingdao faces in terms of agricultural development and ecological conservation. By 2030, under scenarios of natural development, cropland protection, and ecological protection, Qingdao is projected to experience varied degrees of ESV decline, amounting to 1.989 billion, 0.803 billion, and 0.142 billion yuan respectively, with the natural development scenario showing a rapid decrease in ESV around the Jiaozhou Bay area. The spatial ESV patterns under the cropland protection and ecological protection scenarios remain largely consistent with those of 2020, as does the spatial configuration of land use across all scenarios. The ecological protection scenario, demonstrating the least reduction in ESV, emerges as the optimal strategy for balancing urban development with ecological sustainability, advocating it as the preferred pathway for Qingdao's future urban planning. Over the past 35 years, Qingdao's ecosystem services have primarily exhibited synergies, although significant trade-offs remain between agricultural expansion and water supply. Additionally, there are some trade-offs between gas regulation and nutrient cycling with water supply. Under different scenarios for 2030, while the trade-off between agricultural output and water resource conservation persists, the ecological protection scenario significantly enhances synergies among all service categories. This study provides an EFA-PLUS-ESV framework that offers innovations for modeling future ecosystem service values and their trade-offs and synergistic relationships.