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Contrasting effects of long-term acid rain simulation on temperature sensitivity of soil respiration and enzymatic activities in a subtropical forest

Chen, Shutao, Sun, Lu, Zhang, Xu, Shen, Xiaoshuai, Liu, Yifan, Ren, Jingquan
Journal of soils and sediments 2020 v.20 no.1 pp. 412-424
acid rain, analysis of variance, beta-fructofuranosidase, catalase, enzyme activity, forest ecosystems, long term effects, rainfall simulation, soil enzymes, soil respiration, temperature, temporal variation, trenching, tropical forests, urease
PURPOSE: The purpose of this study was to investigate the long-term effects of acid rain simulation (ARS) on soil respiration (Rₛ) components and enzymatic activities. MATERIALS AND METHODS: An 8-year field ARS experiment was conducted in a subtropical forest. A trenching method was used to partition Rₛ into heterotrophic respiration (Rₕ) and autotrophic respiration (Rₐ). Soil urease, invertase, and catalase activities were measured after long-term ARS application. RESULTS AND DISCUSSION: The repeated-measures ANOVA indicated that there was no significant (P > 0.05) difference in annual mean Rₛ (or Rₕ) between SAR plots from March 2016 to February 2018. Rₛ was significantly (P < 0.001) higher than Rₕ for each specific ARS treatment across the 2 years. There were no significant (P > 0.05) differences in Q₁₀ of Rₛ (or Rₕ) between ARS treatments, indicating that the ARS effect on Q₁₀ was not significant. ARS induced a decline in soil urease activity in both untrenched and trenched plots on most measurement dates. The soil invertase and catalase activities were significantly (P < 0.05) reduced by ARS manipulation but had temporal variations. Long-term ARS did not significantly change Rₛ in the untrenched plots or Rₕ in the trenched plots in this subtropical forest ecosystem. CONCLUSIONS: Compared with soil respiration, which is a process involving more biological groups, soil enzymes were more vulnerable to the long-term ARS.