Soil moisture decline in China’s monsoon loess critical zone: More a result of land-use conversion than climate change

作者：Yunqiang Wang, Wei Hu, Hui Sun, Yali Zhao, Pingping Zhang, Zimin Li, Zixuan Zhou, Yongping Tong, Shaozhen Liu, Jingxiong Zhou, Mingbin Huang, Xiaoxu Jia, Brent Clothier, Mingan Shao, Weijian Zhou, Zhisheng An · 发表于：Proceedings of the National Academy of Sciences · 年份：2024 · DOI：10.1073/pnas.2322127121 · 被引用次数：103 · 研究领域：Soil Moisture and Remote Sensing、Climate change and permafrost、Soil and Unsaturated Flow

Soil moisture (SM) is essential for sustaining services from Earth’s critical zone, a thin-living skin spanning from the canopy to groundwater. In the Anthropocene epoch, intensive afforestation has remarkably contributed to global greening and certain service improvements, often at the cost of reduced SM. However, attributing the response of SM in deep soil to such human activities is a great challenge because of the scarcity of long-term observations. Here, we present a 37 y (1985 to 2021) analysis of SM dynamics at two scales across China’s monsoon loess critical zone. Site-scale data indicate that land-use conversion from arable cropland to forest/grassland caused an 18% increase in SM deficit over 0 to 18 m depth ( P < 0.01). Importantly, this SM deficit intensified over time, despite limited climate change influence. Across the Loess Plateau, SM storage in 0 to 10 m layer exhibited a significant decreasing trend from 1985 to 2021, with a turning point in 1999 when starting afforestation. Compared with SM storage before 1999, the relative contributions of climate change and afforestation to SM decline after 1999 were −8% and 108%, respectively. This emphasizes the pronounced impacts of intensifying land-use conversions as the principal catalyst of SM decline. Such a decline shifts 18% of total area into an at-risk status, mainly in the semiarid region, thereby threatening SM security. To mitigate this risk, future land management policies should acknowledge the crucia...