Abstract: Investigating the spatiotemporal evolution of ecosystem service function is conducive to reveal the impact of human activities or climate change on eco-environment, which could also provide a basis for the conservation and management of ecosystem. In this study, remote sensing methods for evaluating ecosystem service function are improved to depict temporal variation. They are subsequently employed to evaluate the functions of headwater conservation, water and soil conservation, and biodiversity maintenance annually from 2000 to 2018 over Huai'an, China. Mann-Kendall non-parametric test and Hurst trend analysis methods are used for spatiotemporal evaluation. The spatiotemporal evaluation is further explored by combining with the interpretations of higher resolution remote sensing data. Results demonstrate that:① The ecosystem service functions of most regions in Huai'an show a significant trend of increasing, among which the increasing trend of headwater conservation and biodiversity maintenance is weak while that of water and soil conservation is strong. ② The increasing trend mainly occurs in cultivated land, woodland, and other vegetated areas. In contrast, the decreasing trend mainly occurs in non-ecological areas such as building land. ③ The area proportion of cultivated land, forestland, and other vegetated areas in Huai'an is basically unchanged, and even slightly decreased with the increase of building land. The significant increase of ecosystem service function in this area may be chiefly due to the enhancement of vegetation vitality, which is represented in the increase of vegetation greenness and vegetation productivity.

Key words: remote sensing, ecosystem service function, spatiotemporal evolution trend, Hurst analysis, Mann-Kendall test