Aridity threshold of ecological restoration mitigated atmospheric drought via land-atmosphere coupling in drylands

Land-atmosphere coupling intensifies the vulnerability of ecosystems in drylands. However, whether and how ecological restoration would modify the land-atmosphere coupling across drylands remains unclear. To address these gaps, here we use structural equation model to separate two pathways of land-atmosphere coupling: vegetation and soil moisture pathways, and investigate the effect of ecological restoration in China's drylands on land-atmosphere coupling. Analysis reveals that, land-atmosphere coupling regulates approximately 30% of atmospheric drought, among which soil moisture pathway contributes twice as much as vegetation pathway. Vegetation greening mitigates atmospheric drought in areas where the aridity index ranges from 0.3 to 0.5, while soil drying exacerbates atmospheric drought in areas where the aridity index ranges from 0.5 to 0.65. The findings identify the optimal regions where ecological restoration helps alleviate the vulnerability of ecosystems under anthropogenic warming. Additionally, the proposed method enhances the understanding of how restored ecosystems contribute to mitigating atmospheric drought.