Legacy effects of trampling on SOC, POC, and MOC​

In this study, we set up an experiment with four trampling intensities (control, light, moderate, and heavy) in a temperate forest to uncover the legacy effects of trampling on SOC content and stability in Jigong Mountain, Central China. All trampling disturbances were completely halted and recovered naturally using exclusion fencing in 2015. Investigations were carried out annually from 2015 to 2017 to analyze the legacy effects on SOC, particulate organic carbon (POC), and mineral-associated organic carbon (MOC). Our results showed that in 2015, soil inorganic nitrogen (SIN), fine root biomass (FRB), and microbial biomass C decreased significantly with increasing trampling intensity, whereas the negative effects weakened over the recovery period. In 2015, light, moderate, and heavy trampling significantly reduced SOC by 27.0%, 25.2%, and 42.9%, respectively. By the third year of recovery (2017), the negative impact decreased to 13.4% under moderate and 23.6% under heavy trampling, while no effect was detected under light trampling. Moderate and heavy trampling significantly reduced POC by 7.4–23.9% during 2015–2016. The negative effect under light trampling decreased from 13.7% in 2015 to 9.7% in 2016; while no effects of trampling treatments were detected on POC in 2017. In contrast, moderate and heavy trampling consistently suppressed MOC across the study period, although the reduction under heavy trampling declined from 21.1% in 2015 to 11.3% in 2017.