Spatiotemporal variation in topsoil salt content and its key determinants in the Kubuqi Desert

JING Sisi; CHEN Haorui; WU Lipeng; CHEN Junying; YE Sumeng; QIAN Long; WU Yuxiao; MIAO Ping; MA Hongli

doi:10.13522/j.cnki.ggps.2025133

Abstract：[Objective]The Kubuqi Desert in Inner Mongolia is an ecologically fragile region;understanding the spatiotemporal variation of topsoil salt content(SSC)and its controlling factors is crucial for sustainable land management in the region.This paper develops a method to map SSC variation over time and identify the key meteorological drivers influencing SSC distribution.[Method]Based on measured soil data,an SSC inversion model was developed using ReliefF feature selection and machine learning algorithms.The model was then applied to generate surface SSC maps for the northern margin of the Kubuqi Desert from 2000 to 2024.Trend analysis,correlation analysis,and geographic detector methods were used to examine the spatiotemporal variation in SSC and its relationships with meteorological variables.[Result]① The PSO-SVM algorithm outperformed PLSR and RF in inversely calculating SSC,with R2=0.63,RMSE=0.009 and MAE=0.007.② From 2000 to 2004,the annual SSC at the northern edge of the desert showed a fluctuating but increasing trend.③ Spatially,the SSC was significantly heterogeneous,with its value increasing from the southwest to the north.At the pixel scale,SSC was strongly correlated with temperature and precipitation,but weakly with vapor pressure and mixing ratio.④ Temperature,precipitation,vapor pressure deficit,and wind speed had high explanatory power for the SSC changes,representing the primary meteorological drivers of spatiotemporal variation of SSC.[Conclusion]SSC in the northern margin of the Kubuqi Desert shows pronounced spatiotemporal variation.Temperature and precipitation are the dominant factors shaping this variation.These results can help improve management of salt-affected soil in the desert.