Reduction in sediment yields from karst terrain in SW China over the past 600+ years

Abstract

Previous studies have examined sediment yields and erosion in karst settings over recent decades, with little consideration of the evolution of rocky desertification over longer timescales. Here we reconstruct sediment yields from karst terrain in SW China over the past 600+ years by dating sediment deposition in a representative karst depression, and assess the contribution of historical sediment yields to rocky desertification. Results indicate that area-specific sediment yields (SSYs) during the early stage of sediment deposition (1368–1652) were the highest, triggered by deforestation and then cultivation associated with the first Hu-Guang Fills Sichuan migration during the Ming Dynasty. The relatively high SSYs during the middle stage (1653–1922) were related mainly to cultivation associated with the second Hu-Guang Fills Sichuan migration rather than deforestation, including the introduction of maize (Zea mays) and sweet potato (Ipomoea batatas) during the Qing Dynasty. SSYs increased again during the modern stage (1923–1962) due to massive deforestation at the end of the 1950s. During the latest stage (1963–2022), SSYs were the lowest as a result of increasing rocky desertification, reduced human disturbance, and the restoration of vegetation. The contributions of sediment yield to rocky desertification decreased across the middle, modern and latest stages, suggesting that the present-day rocky desertification was caused mainly by sediment yield stimulated by human activity over the past 500+ years before 1923, rather than over recent decades. Overall, our study provides more-comprehensive insights into the dynamics of rocky desertification over long timescales.