Detection and comparison of spatiotemporal patterns and drivers of NEP in the river economic belt

• NEP in YZEB shows high but slow growth, while YREB exhibits rapid improvement. • Spatial NEP patterns diverged: YZEB decreased southwest-to-northeast vs. YREB’s banded southeast-to-northwest decline. • Driving mechanisms differ between belts and along reaches, shifting from natural to human–land coupling. The Yellow River Ecological Economic Belt (YREB) and the Yangtze River Economic Belt (YZEB) are vital ecological security barriers in China, with Net Ecosystem Productivity (NEP) serving as an indicator of regional carbon sink capacity. Existing studies have mostly focused on individual regions, lacking systematic comparative analysis. This study employs trend analysis, the Hurst index, and the Geodetector method to investigate the spatiotemporal dynamics, driving factors and interaction mechanisms of NEP in the two economic belts from 2001 to 2020. The results indicate that: (1) the YZEB maintains a relatively high NEP baseline but with slow growth, while the YREB, despite its lower baseline, has achieved rapid improvement driven by land-use adjustment, and large-scale ecological restoration projects. (2) Spatially, NEP in the YZEB decreases from southwest to northeast, whereas in the YREB it declines from southeast to northwest. Hurst index and trend analysis results indicate that most areas in both belts exhibit weak persistence, with the YREB showing greater future carbon sink potential.(3) Regarding driving mechanisms, the YZEB is primarily topography-driven, transitioning internally from a “topography–climate coupling” pattern upstream, to “multi-factor synergy” in the midstream, and “human–land coupling” downstream. In contrast, the YREB is vegetation-dominated, evolving from “natural–topography driven” in the upstream, to “climate–vegetation synergy” in the midstream, and “human–nature interactions constrained by water resources” in the downstream region. This study reveals the differentiated mechanisms underlying NEP evolution in the two belts and proposes region-specific management strategies, providing scientific support for targeted carbon sink enhancement and sustainable ecological management.