A comparative study of long-term historical soil erosion in the four major Mollisols regions of the world

The Mollisols are among the world's most fertile soils but are increasingly threatened by erosion due to intensive cultivation and climate change. Despite their importance for global food production, the long-term dynamics of soil erosion in the four major Mollisols regions of the world as well as their comparisons and the control factors remain poorly understood. The Revised Universal Soil Loss Equation (RUSLE) was applied to estimate historical soil erosion from the 1900s to the 2020s across the four major global Mollisols regions, including the Mississippi Plain (MSP), the Northeast China Plain (NEC), the Pampas Plain (PP), and the Ukrainian Plain (UP). Scenario analysis, machine learning, and driver separation approaches were combined to quantify the contributions of driving forces to soil erosion during the past over 100 years. The results indicate that soil erosion has intensified across all regions during the past century. The NEC experienced the largest erosion intensity and increase, with mean erosion rates rising from 5 to 18.6 t·ha −1 ·yr −1 and a mean decadal increase of 0.95 t·ha −1 ·yr −1 , followed by the MSP (0.12 t·ha −1 ·yr −1 per decade), UP (0.11 t·ha −1 ·yr −1 per decade), and PP (0.10 t·ha −1 ·yr −1 per decade). Spatially, erosion expansion was widespread for all the four regions, particularly in mountainous and hilly landscapes, and LS-factor explained 35–55% of erosion variability. Scenario analysis indicated that land use change controlled long-term erosion trends in the NEC, climate-driven changes reproduced most of the observed increases in the UP, while both greatly affected erosion dynamics in the PP. In the MSP, erosion trajectories transitioned from land-use dominance in the early 20th century to increasing climate influence after the 1970s. These findings emphasize the urgent need for region-specific strategies to mitigate erosion risks in the four major Mollisols regions, especially for NEC.