Research on the dynamics and ecological thresholds of groundwater-dependent vegetation in the plain area of the Golmud River Basin

In arid inland river systems, surface water and groundwater interact and transform frequently, exerting profound effects on vegetation distribution in inland basins—a pattern mirrored by groundwater-dependent vegetation in the Golmud River Basin plain. By integrating field-monitored groundwater depth and TDS data with remote sensing-derived Normalized Difference Vegetation Index (NDVI) imagery, this study examines the dynamic influences of groundwater depth and TDS on vegetation cover. Key findings indicate that the ecological threshold for oasis vegetation dependence on groundwater in the Golmud River Basin plain is a depth of 4 m and TDS of 2.8 g/L. Beyond 4 m depth, vegetation cover declines precipitously, with growth exhibiting minimal groundwater influence. Depths < 0.5 m are optimal for aquatic vegetation but prone to soil salinization. Suitable groundwater depths for dominant species are: Phragmites australis (0.10–3.95 m), Tamarix chinensis (0.90–4.62 m), Nitraria sibirica (1.0–3.28 m), and Apocynum venetum (0.90–3.95 m). When TDS exceeds 2.8 g/L, high NDVI values diminish sharply, reducing vegetation cover; growth ceases entirely at 6.5 g/L TDS.