Spatiotemporal dynamic and synergistic patterns of water yield and soil conservation services in Shandong Province: Insights from a twenty-year evaluation

Water yield and soil conservation are critical ecosystem services that support regional ecological security and human well-being. However, long-term fine-scale assessments of their spatiotemporal dynamics and interactions remain limited, particularly in erosion- and water-stressed regions. This study evaluates these services in Shandong Province (2000–2019) using the Integrated Valuation of Ecosystem Services and Trade-offs (InVEST) water balance model and Revised Universal Soil Loss Equation (RUSLE), parameterized with remote sensing, meteorological, and soil datasets. Pixel-level analyses were used to assess quantity, seasonality, and monotonic trends using the seasonal Mann‒Kendall test. The mean annual water yield was 143.49 mm (SD=96.70 mm), and the mean annual soil conservation capacity was 5,272.80 t/km 2 (SD=413.31 t/km 2 ). Forests exhibited higher per-unit capacity than croplands and grasslands, though their limited spatial extent reduced overall contributions. Significant monotonic declines in water yield (10.5% of the province) were observed, primarily in the central and eastern regions, contributing to an overall decreasing trend. Conversely, soil conservation declined in only 4.5% of the area. A robust synergy between services was observed from pixel-wise Theil-Sen regression analysis, with ∼27% of the area showing stable covariation (R 2 >0.30). Spatially explicit identification of degradation hotspots supports targeted ecological restoration, particularly in coastal and hilly regions that observed significant water yield declines. Future management needs a policy adjustment from general soil stabilization toward water yield enhancement and their co-provision optimization. This fine-scale, decadal analysis advances methodologies for coupled service assessment while providing actionable insights for balancing soil-water conservation in rapidly developing regions. • Monthly WY and SC were evaluated across Shandong Province during 2000-2019 • Variability, trend, and seasonality were illustrated at provincial and pixel levels • Hydrologically vulnerable areas primarily clustered in intensive farming regions • Robust synergistic coupling between WY and SC in the central and southeast parts