Changes in Soil Organic Carbon in a Metasequoia Plantation During Recovery Following Different Trampling Intensities

ABSTRACT

The content and stability of soil organic carbon (SOC) serve as key indicators of soil carbon (C) sink function. Tourist trampling, a widespread anthropogenic disturbance in many natural ecosystems, is a primary driver of soil degradation. However, how SOC and its fractions change during the recovery period following tourist trampling of different intensities remains poorly understood. In this study, we established an experiment with four trampling intensity levels (control, light, moderate and heavy) in a Metasequoia plantation to investigate the legacy effects of trampling on SOC, particulate organic carbon (POC) and mineral‐associated organic carbon (MOC). All trampling disturbances were completely halted in 2014, and the soil was allowed to recover naturally from 2015 to 2017 within exclusion fencing. Our results showed that in 2015, light, moderate and heavy trampling significantly reduced SOC by 26.3%, 33.3% and 55.4%, respectively. By the third year of recovery (2017), the negative effect on SOC had weakened and decreased to 12.4% under moderate and 26.5% under heavy trampling, with no effect detected under light trampling. For POC, heavy trampling caused a significant reduction of 23.1%–24.6% during 2015–2016, whereas the negative effect of light trampling decreased from 12.4% in 2015 to 9.0% in 2016. By 2017, no trampling treatment had a detectable effect on POC. In contrast, moderate and heavy trampling consistently suppressed MOC across the study period, with a reduction from 20.9% in 2015 to 13.0% in 2017 under heavy trampling. Stepwise regression analysis revealed that soil available phosphorus and fine root biomass together accounted for the variation of SOC, whereas specific root length emerged as the primary factor explaining the variation in MOC. This study demonstrates that trampling exerts stronger and more persistent legacy effects on total SOC and MOC than POC. Soil function recovers relatively quickly following light trampling, but more severe degradation caused by heavy trampling requires longer restoration periods.