Land use effects on desertification sensitivity in arid Northwest China: A comparison of direct and indirect pathways

Desertification poses a challenge to dryland sustainability. Land use change, as an important driver of desertification sensitivity, has been studied mainly for its direct impacts, whereas indirect effects remain inadequately considered. Applying a MEDALUS-LightGBM-InVEST framework, this study quantified land use effects on desertification sensitivity in the Tarim Basin during 2000-2020, comparing direct effects through surface-cover change with indirect effects mediated by water resources. Results showed that conversion of grassland and unused land to cultivated land was the main land use change, directly reducing desertification sensitivity while tending to increase sensitivity indirectly. Decreased sensitivity dominated direct effects in both periods. During 2000-2010, sensitivity decreased across 3320.50 km² and increased across 670.75 km², with an average change of -6.11% among affected dynamic pixels. During 2010-2020, the corresponding areas were 3096.25 km² and 713.00 km², with an average change of -4.08%. Indirect effects showed a contrasting pattern. During 2000-2010, increased sensitivity (1707.50 km²) slightly exceeded decreased sensitivity (1608.25 km²), although the mean change was -0.16%, with mean estimates of +0.25% and +0.08% for desert-type and agricultural-type watersheds, respectively. During 2010-2020, the increased area reached 2179.75 km², 2.25 times the decreased area, with a +0.21% mean estimate among affected dynamic pixels. Shapley decomposition showed that the direct pathway dominated in both periods (-6.158% and -4.839%), while the indirect pathway estimate shifted from -0.283% to +0.126%. These findings reveal contrasting direct and indirect land use effects and provide a scientific basis for ecological restoration in arid regions.