Analysis of the evolution characteristics and driving mechanisms of salinization in arid regions based on multi-factor interaction with optimized parameter geographic detector (OPGD)1.

Understanding the mechanisms of saline-alkali in arid oasis regions is crucial for ecological security. This study integrates multi-source spatiotemporal data with the Optimized Parameter Geographic Detector (OPGD) model. The analysis utilizes 1511 soil samples collected in 2022 alongside multi-year remote sensing interpretation results. By quantifying eleven water-soil-vegetation-human activity driving factors, the research systematically reveals the patterns, evolution, and driving mechanisms of soil salinization in the Kashgar Plain oasis. Key findings include: (1) The area exhibits chloride-sulfate type severe salinization (average soil salinity 19.17 g/kg), with spatial heterogeneity characterized by an overall low salinity level but with localized severe salinization hotspots, and a pattern of lighter in the south and heavier in the north. The northern regions (Jiashi-Bachu) are high-risk hotspots (with 18.62 % of areas severely salinized). Sodium ions dominate (accounting for 34.6 % of cations), highlighting risks associated with sodium accumulation; (2) Post-2010 policies supporting Xinjiang's development drove large-scale reclamation and oasis expansion (+9885 km²), contributing to regional economic development. However, this rapid land-use change in ecologically vulnerable northern areas inadvertently altered the local water-salt balance, leading to a notable expansion of secondary salinization (+5753 km²) against the backdrop of overall oasis improvement. This has created a spatially divergent pattern of "deterioration in the north, improvement in the south, and stability in the central"; (3) The OPGD model identifies land use as the primary anthropogenic driver (Q = 0.2479), while groundwater systems (depth and mineralization) serve as natural key factors. Interaction effects between factors were prevalent and significant, primarily exhibiting bivariate enhancement. Notably, the interaction between groundwater mineralization and vegetation cover (X9∩X10) demonstrated nonlinear enhancement (Q = 0.2715), which is stronger than the sum of their individual effects. Thresholds for risk are first defined: mineralization degree >14 g/L and groundwater depth exhibiting a bimodal risk distribution (<6.06 m and >43.1 m). The findings provide a theoretical framework for the precise management of saline-alkali land along the Silk Road Economic Belt.