Soil multifunctionality in the face of climate change and human impact in China’s drylands

The United Nations has designated 2021–2030 as the “Decade on Ecosystem Restoration” to combat ecosystem degradation. Climate change and human activities are the primary drivers of this degradation, which has significantly impacted soil multifunctionality (SMF) in China’s drylands. However, the effects of human activities, particularly those related to ecological restoration policies, remain poorly understood. Here, we evaluated the influence of climate change and human activities on five soil functions based on 18,189 observations from 841 studies in China’s drylands and used machine learning methods to forecast future changes. We found that warming and precipitation changes had overall minimal effects on SMF. In contrast, nitrogen deposition improved it by 13.4%, mainly by enhancing soil nutrient supply and productivity. Human activities, particularly ecological restoration, had a greater impact on SMF than climate change. For instance, policies like the Grain for Green Program enhanced the climate regulation function by 32.2%. Further, we found that local climate conditions primarily influenced SMF responses to climate change, while the duration of restoration efforts shaped responses to human activities. Our projections of SMF under the sustainable emission scenario (SSP1-2.6) suggested that well-planned ecological restoration was likely to sustain and enhance SMF over time, particularly in hyper-arid areas. These findings highlight that human activities exert a more significant influence on SMF than climate change in China’s drylands and may provide a scientific basis for sustainable management and ecological restoration of arid ecosystems.