长白山阔叶红松林土壤温室气体通量的动态变化及其对土壤冻融的响应OA

Soil greenhouse gas emissions are a critical component in assessing the function of ecosystems as carbon sources and sinks.Soil freeze-thaw cycles influence these emissions by altering soil carbon(C)and nitrogen(N)cycling.However,there remains a limited understanding about the temporal variations in soil greenhouse gas fluxes during freeze-thaw periods and the regulating factors.We conducted in-situ observations of soil greenhouse gas flu-xes with the method of static chambers in a temperate broadleaf Korean pine forest in Changbai Mountain,and ana-lyzed the impact of soil variables on greenhouse gas emissions.The results showed that soils acted as a CO2 and N2O source and a CH4 sink during 2019-2021.The annual cumulative fluxes of soil CO2,CH4,and N2O were 107.96±8.32,-50.99±7.41,and 10.17±2.41 mmol·m-2·a-1,respectively.Soil CO2 emission and CH4 uptake during the spring freeze-thaw period were significantly lower than those in the growing season,while N2O emission was much higher.The cumulative fluxes of soil CO2 and CH4 during the spring freeze-thaw period contributed 5.51％and 8.44％to the annual total fluxes respectively,while the contribution of N2O flux reached 51.43％.Multivariate regression analysis revealed that during the spring freeze-thaw period,CO2 fluxes increased with rising soil tempera-ture,and that soil temperature had minimal effects on CH4 and N2O fluxes.In the growing season,CO2 fluxes were primarily influenced by soil temperature and soil NO3-content in surface layer.CH4 fluxes were mainly regulated by soil moisture,while N2O fluxes were weakly affected by soil pH.Soil freeze-thaw exerts a remarkable effect on the temporal variations of greenhouse gas emissions.Considering the complexity of soil C and N cycling and soil hetero-geneity,more observations are required on greenhouse gas emissions and control mechanisms to accurately assess the role of soil in ecosystem C sequestration.