Response of soil respiration and its components to different rainfall patterns in riparian poplar plantations

Objective This paper aims to determine the differences in the response of soil respiration and its components under different rainfall patterns and their causes, so as to provide theoretical guidance for accurate prediction and modeling of the process of soil carbon cycle and terrestrial carbon sink capacity in the context of global change.

Method In this research, conducted from 2018 to 2019, we continuously monitored soil respiration, including both autotrophic and heterotrophic respiration. We used K-means clustering to classify rainfall patterns, investigating the effects of natural rainfall on environmental variables and the rate of soil respiration.

Result (1) The total soil respiration rate decreased by 41.6%, 36.3%, and 45.8%, respectively under the intensity of light rainfall over a long duration, light rainfall with a moderate duration and heavy rainfall with a short duration, and the heterotrophic respiration rate decreased by 60.5%, 41.2%, and 85.1%, respectively; the autotrophic respiration rate decreased by 11.7% and 30.0% under light rainfall with a long duration and light rainfall with a moderate duration, respectively, and increased by 72.5% under heavy rainfall with a short duration. (2) Heterotrophic respiration responded more quickly to rainfall and changed more dramatically after rain. (3) Rainfall events affected respiration rates by changing soil moisture, and soil temperature did not change significantly before or after rainfall.

Conclusion With the increase in rainfall intensity or the extension of rainfall duration, the inhibitory effects on soil respiration and heterotrophic respiration become more significant. Compared with autotrophic respiration, heterotrophic respiration is more sensitive to rainfall. Rainfall mainly influences soil respiration by altering heterotrophic respiration.