Soil Erosion Evolution and Its Response to Human Activities over the Past ~250 Years in Two Karst Depressions of Chongqing, Southwest China

ABSTRACT

To assess the long‐term sustainability of soil retention in erosion‐prone karst regions, investigating historical soil erosion processes and their mechanisms in Southwest China, a typical karst‐dominated region, is essential. While soil erosion processes over the last ~60 years have been widely examined in Southwest China, longer term records remain rare. Here, we examined soil erosion processes in two karst depressions over the past ~250 years in Chongqing Municipality, located in the northern part of Southwest China, utilizing ¹³⁷ Cs, ²¹⁰ Pb and AMS ¹⁴ C dating on sediment profiles. These results were then compared with published soil erosion rate data to identify how soil erosion processes in Chongqing are similar to or different from those in other parts of Southwest China. The results exhibited high soil erosion rates from ~1750s to ~1935–1945

at both depressions, related to the Hu‐Guang Fills Sichuan Migration, Zea mays cultivation expansion, and elevated precipitation. Erosion rates declined after ~1935–1945  , likely due to wartime impacts. Slight soil erosion peaks appeared during ~1950–1960  , linked to the Great Leap Forward and the Great Steel Campaign. Subsequently, a long‐term decline in soil erosion rate occurred from ~1960s to 2018  . A compilation of published data reveals that this declining trend was in fact a region‐wide phenomenon in karst regions across Southwest China. This period of soil erosion decline is possibly linked to reduced erodible soil stocks due to earlier severe erosion and cessation of the Great Steel Campaign and hence reduced deforestation, combined with the large‐scale ecological restoration projects implemented since the 1990s. This study provides a scientific basis for projects of improving sustainability of karst ecological restoration.