Vegetation change in the Manas River Basin: dominance of groundwater-agricultural land synergy

• Quantifying key drivers and their interactions in oasis vegetation dynamics. • Groundwater-ecological interactions are a primary factor driving vegetation change. • Cropland expansion and groundwater decline threaten oasis sustainability. Understanding vegetation dynamics and their response mechanisms to multidimensional drivers is essential for elucidating ecosystem processes under global change. The Manas River Basin in Xinjiang, a critical oasis ecosystem in arid regions, plays a strategic role in maintaining regional ecological security. This study analysed spatiotemporal variations in fractional vegetation coverage (FVC, 250 m × 250 m) and quantified the primary driving factors and their interactions from 2013 to 2022 using Random Forest (RF) and the Geographical Detector Model (GDM). The results showed an overall decline in FVC across the basin (- 0.0005/year), with a sharper decrease during 2013–2015 (- 0.01/year) compared to 2016–2022 (- 0.006/year). This degradation was primarily due to significant reductions in low-moderate (- 0.00002/year), moderate (- 0.0012/year), and moderately high (- 0.0026/year) vegetation cover levels. RF analysis identified farmland area (0.128) and groundwater depth (0.119) as key determinants of vegetation changes. Groundwater exhibited a stable influence, while agricultural expansion became increasingly dominant. GDM interaction analysis revealed that groundwater depth, combined with other factors (q = 0.65–0.96), farmland area, combined with other factors (q = 0.46–0.91), and ecological land area, combined with other factors (q = 0.49–0.88), synergistically enhanced vegetation dynamics. These findings confirm the critical role of these three factors in driving variations in FVC.. This study offers valuable insights into balancing ecological conservation and agricultural development in arid regions, highlighting the importance of sustainable groundwater management and rational farmland planning to ensure both ecological security and agricultural sustainability.