From decline to improvement: The shift in ecosystem service trends (1990–2020) in the Heihe River Basin driven by vegetation

Heihe River Basin (HRB). This study identified the spatiotemporal patterns and trend shift types of ecosystem services (ESs) during 1990–2020 and evaluated the relative importance of the drivers across different periods. Five ESs (water yield, carbon storage, soil retention, habitat quality, and food production) were selected based on their consistency with the Millennium Ecosystem Assessment classification and their relevance to the characteristics of endorheic basins. Breakpoint analysis was applied to detect significant transitions in ecosystem service trends and classify shift types. The proportion of areas with improved ESs rose from 64 % to 80 %, and 55 % of the region experienced a shift in ESs from declining to increasing (D-I). The D-I shift in the upstream area (1990–2000) coincides with the period of significant reduction in ice/snow area, while the D-I shift in the midstream (2001–2005) and downstream (2011–2020) areas aligns with the period when the ecological water diversion project played a significant role. Increased precipitation promoted vegetation recovery upstream, whereas ecological engineering facilitated vegetation restoration midstream and downstream, driving the D-I shifts. By identifying the timing, dominant drivers, and spatial heterogeneity of ecosystem service trend shifts, this breakpoint-based framework supports the assessment of ecological interventions and adaptive water and ecosystem management. The approach is transferable to other arid endorheic basins along the Belt and Road. • The proportion of areas with improved ecosystem services rose from 64 % to 80 %. • A total of 55 % of the area shifted from decline to improvement in ecosystem services. • The timing of the D-I shift was delayed by 5–10 years from upstream to downstream. • Vegetation recovery led the shift in ecosystem services from decline to improvement.