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

Abstract

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. 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. 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 0.05) 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. Compared with soil respiration, which is a process involving more biological groups, soil enzymes were more vulnerable to the long-term ARS.