Holocene soil erosion in response to climate variability in the southern Chinese Loess Plateau

Soil erosion is a major environmental challenge in arid and semi-arid regions of the world, and the relationship between climate and soil erosion has received considerable attention. Looking into long-term environmental variability would help quantify this relationship more accurately. New stratigraphical, physical-chemical, and micromorphological data from three representative loess-palaeosol sections—Milucun, Wufang, and Qishan—have been analysed to reconstruct the Holocene history of soil moisture and erosion in the southern Chinese Loess Plateau. The findings divide the Holocene into five stratigraphical units: two palaeosol (S₀₁ and S₀₂) and three loess layers (L₀, L_x, and L_t), each reflecting a stage of monsoon patterns, sandstorm activity, temperature, and precipitation changes. Notably, during the formation of the early mid-Holocene palaeosol S₀₂, average temperature was around 15.1 °C with annual precipitation of 808 mm, of which the East Asian summer monsoon contributed approximately 450 mm, surpassing non-monsoon sources of ca. 360 mm. The development of secondary argillans and dense woody root traces within S₀₂, alongside shifts in clay mineral content, suggest elevated soil moisture between 8500 and 6000 years ago. This moisture likely sustained gravitational water, fostering a positive soil moisture balance and supporting lush forest vegetation. This study proposes that interglacials and interstadials experienced weaker soil erosion due to better vegetation cover, while glacials and stadials saw intensified erosion. A clear example is the L_x formation between 6000 and 5000 years ago, during which significant erosion led to the loss of this thin loess layer in much of the plateau.