LAUSR

Purpose The purpose of this study was to investigate the long-term effects of acid rain simulation (ARS) on soil respiration ( R s ) 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 R s into heterotrophic respiration ( R h ) and autotrophic respiration ( R a ). 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 R s (or R h ) between SAR plots from March 2016 to February 2018. R s was significantly ( P  < 0.001) higher than R h for each specific ARS treatment across the 2 years. There were no significant ( P  > 0.05) differences in Q 10 of R s (or R h ) between ARS treatments, indicating that the ARS effect on Q 10 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 R s in the untrenched plots or R h 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.