河岸杨树人工林土壤呼吸及其组分对不同降雨模式的响应

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

【目的】确定不同降雨模式下土壤呼吸及其组分的响应差异及其原因,为精确预测和模拟全球变化背景下土壤碳循环的过程和陆地碳汇能力提供理论指导。【方法】对两年(2018—2019年)土壤呼吸及其组分(自养呼吸和异养呼吸)进行连续测量,并利用K-均值聚类分析对降雨进行分类,探究自然降雨过程对环境因子和土壤呼吸速率的影响。【结果】(1)土壤呼吸速率在长历时小雨、中历时小雨和短历时大雨下分别降低41.6%、36.3%和45.8%,异养呼吸速率分别降低60.5%、41.2%和85.1%;自养呼吸速率在长历时小雨和中历时小雨下分别降低了11.7%和30.0%,在短历时大雨下提高了72.5%。(2)异养呼吸对降雨的响应更快且雨后变化幅度更大。(3)降雨事件通过改变土壤湿度影响呼吸速率,土壤温度在降雨前后变化不显著。【结论】随着降雨强度增加或降雨持续时间的延长,土壤呼吸和异养呼吸受到的抑制效果愈发显著,且相较于自养呼吸,异养呼吸对降雨的响应更为敏感,降雨主要通过改变异养呼吸来影响土壤呼吸。

[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.