Soil hydrological processes and drought response of typical vegetation in arid regions under long-term climate patterns

Arid desert region in northwest China. Understanding the long-term soil water dynamics and vegetation water-use strategies is vital for sustainable management of ecosystem in arid regions. This study integrates field data and Hydrus-1D modeling to assess water use efficiency, drought resistance, and water conservation capacity of five vegetation types—bare land (BL), grassland (GL), Salix psammophila (SP), Caragana korshinskii (CK), and Pinus sylvestris var. mongolica (PSVM) under four distinct climatic conditions in the Mu Us Sandy Land over 1980–2022. CK exhibited the strongest drought resistance and water conservation capacity, especially in the continuous drought scenario, it maintained 0.028 cm 3 ·cm −3 of available water space and 7 % deep rainfall-percolation rate. In contrast, other vegetation types showed near-zero deep percolation and showed pronounced soil moisture deficits of root depths. The response to vapor pressure deficit (VPD) can be used as a threshold index for vegetation resistance, with the highest threshold in CK (1.61), followed by GL (1.32) and SP (1.30), and lowest value is PSVM (1.07). Furthermore, Statistic data further suggested that a 10 % reduction in BL led to a 5.28 % decrease in deep percolation, highlighting the role of BL in maintaining groundwater recharge. Based on these findings, we propose a detailed vegetation-planting restoration strategy to enhance groundwater replenishment, which is crucial for addressing current soil and groundwater stress. • Caragana korshinskii exhibits the highest drought resistance and water conservation. • Vapor pressure deficit is a key factor in regulating vegetation drought tolerance. • Moderate bare land retention enhances groundwater recharge.