<p>Due to the air pollutant emissions, acid rain in southern China may strongly influence soil organic carbon (SOC) decomposition and stabilization by disrupting microbial communities and associated enzymatic processes. In this study, we conducted a field experiment in a subtropical forest in southern China, by implementing simulated acid rain (SAR) treatments with varying pH levels (4.5 as a control, 4.0, 3.5, and 3.0) to investigate the effects of acid rain on soil microbial community composition, carbon (C)-degrading enzyme activities, an both labile and stable SOC fractions. Results showed that SAR treatments significantly altered the soil microbial community and reduced several key C-degrading enzyme activities (e.g., <i>β</i>-glucosidase by −22% – −55%, phenol oxidase by −32% – −71%, and peroxidase by −4% – −71%). Accordingly, SAR treatments increased liable SOC content by 3%–150% and stable SOC content by 1%–52%, leading to increases in total SOC content by 5%–29%. These findings demonstrate that acid rain can suppress soil microbial productions of C-degrading enzymes, thereby promoting the accumulation of both labile and stable SOC fractions. The differential responses of labile and stable SOC fractions to prolonged acid rain exposure may have important implications for the long-term sequestration and stability of SOC in subtropical forests soils in southern China.</p>

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Effects of prolonged acid rain on labile and stable soil organic carbon fractions in a subtropical forest

  • Qi Deng,
  • Jianling Li,
  • Xin Xiong,
  • Huiling Zhang,
  • Jianping Wu

摘要

Due to the air pollutant emissions, acid rain in southern China may strongly influence soil organic carbon (SOC) decomposition and stabilization by disrupting microbial communities and associated enzymatic processes. In this study, we conducted a field experiment in a subtropical forest in southern China, by implementing simulated acid rain (SAR) treatments with varying pH levels (4.5 as a control, 4.0, 3.5, and 3.0) to investigate the effects of acid rain on soil microbial community composition, carbon (C)-degrading enzyme activities, an both labile and stable SOC fractions. Results showed that SAR treatments significantly altered the soil microbial community and reduced several key C-degrading enzyme activities (e.g., β-glucosidase by −22% – −55%, phenol oxidase by −32% – −71%, and peroxidase by −4% – −71%). Accordingly, SAR treatments increased liable SOC content by 3%–150% and stable SOC content by 1%–52%, leading to increases in total SOC content by 5%–29%. These findings demonstrate that acid rain can suppress soil microbial productions of C-degrading enzymes, thereby promoting the accumulation of both labile and stable SOC fractions. The differential responses of labile and stable SOC fractions to prolonged acid rain exposure may have important implications for the long-term sequestration and stability of SOC in subtropical forests soils in southern China.