A study on the spatiotemporal changes and driving mechanisms of saline-alkali lands in the western Songnen Plain, 1990–2023

Introduction Land salinisation is a serious land degradation issue in drylands. A systematic analysis of the spatiotemporal evolution and driving mechanisms of saline-alkali land in the western Songnen Plain was conducted in this study. Methods Based on eight 30 m land-use datasets spanning 1990–2023 and integrating transfer matrix, centroid migration, Partial Least Squares Structural Equation Modelling (PLS-SEM), Multiscale Geographically Weighted Regression (MGWR), and Optimal Geographical Detector Optimal Parameter Geodetector approaches. Results and Discussion The results indicate that: (1) The extent of saline-alkali land first experienced fluctuations and increases, followed by a continuous decrease. From 1995 to 2000, saline-alkali land rose at its fastest rate, but has experienced a net decrease since 2010, with a total net loss of roughly 200.47 km 2 across the study horizon. Stable saline patches are mainly clustered in the central region, while the largest reductions are clustered in south-western Zhenlai County. The centre of gravity shifted first towards the south-west and then towards the north-east, becoming relatively stable after 2010; (2) Human activities (gross domestic product, Pop, grazing intensity) and terrain (DEM, Slope) were the dominant driving factors over the long term; these factors interacted significantly, and their joint explanatory power exceeded that of any individual factor. (3) The impact of these driving factors exhibited spatial heterogeneity: from 1990 to 2010, human activities and vegetation served as the primary driver, whereas the 2010–2023 period witnessed a transition toward the combined influences of topography, climate, and ecology—findings that underpin zone-specific management and ecological rehabilitation for the Songnen Plain and other soda saline areas.