Continuous organic mulching enhances the stability of soil organic carbon in Phyllostachys praecox: A 5-year in situ experiment

5-year mulching increased SOC stability and concentration in Phyllostachys praecox forests.Soil POC was mainly regulated by soil AP concentration and fungal community.Soil MAOC was mainly regulated by soil pH, enzyme activities, and bacterial diversity.Soil pH and bacterial diversity were the dominant drivers of the SOC stability.Organic mulching is widely applied in agricultural and forest ecosystems to improve crop yields and maintain soil quality. However, its long-term impact on soil organic carbon (SOC) stability and the underlying mechanisms remain unclear. An in situ experiment was initiated in 2018 in the subtropical region of China, with the non-mulched treatment serving as the control group (0 year of mulching), to investigate the effects of mulching on the organic carbon components (particulate organic carbon, POC, and mineral-associated organic carbon, MAOC) in Phyllostachys praecox bamboo forests across different mulching durations of 1, 3, and 5 years. Our results indicated that five-year mulching decreased soil POC concentration by 13.36%, while increasing MAOC and SOC by 130.3% and 64.53%, respectively, compared to no mulching. The POC/MAOC ratio dropped, indicating improved SOC stability. Additionally, soil pH decreased with mulching duration, while bacterial and fungal diversity, available phosphorus content, and beta-xylosidase activity significantly increased. Structural equation modeling indicated that POC was mainly regulated by available phosphorus and fungal communities. While MAOC was affected by soil pH, which also mediated its response by influencing enzyme activity and bacterial diversity. In bamboo forest ecosystems, long-term organic mulching enhances SOC sequestration and stability, providing insights into SOC management for sustainable forestry. Such information indicates continuous mulching can be used to improve SOC sequestration in subtropical bamboo ecosystems.