Effects of Exogenous Nitrogen Input on Soil CO2 Flux in Larix gmelinii Forests in Cold Temperate Zone
Exogenous nitrogen input affects the stability of physical and chemical properties of the forest soil,which in turn affects its CO2 flux.Three nitrogen input levels,i.e.,low nitrogen N1(10 kg/hm2),medium nitrogen N2(20kg/hm2),high nitrogen N3(30kg/hm2),and control group(CK),were set in the soil of Larix gmelinii forests in the cold temperate zone.Static chamber-gas chromatography method was used to measure the soil CO2 flux from May to September,and the path equation was established to analyze the relation-ship between soil TS10,MS10,TN,NH4+-N and NO3--N,and soil CO2 flux.The influence of exogenous nitrogen input on the soil CO2 flux in the Larix gmelinii forests was clarified.The results showed that,the contents of soil TS10,MS10,TN,NH4+-N and NO3--N in-creased first and then decreased,and the soil NO3--N content showed an overall decreasing trend.With the nitrogen input level in-creasing,the contents of TS10、TN、NH4+-N and NO3--N gradually increased,while MS10 gradually decreased.The soil CO2 flux showed a significant unimodal variation with seasonal variations,with the peak occurring in August.Appropriate nitrogen input could significantly increase the soil CO2 flux,and vice versa,inhibit soil CO2 emission.The CO2 flux in the control group soil was positively correlated with soil TS10 and MS10.The soil CO2 fluxes at different nitrogen input levels were closely related to the soil TN and NH4+-N content,but not to the soil NO3--N content.
Nitrogen inputSoil CO2 fluxInfluence factorLarix gmelinii forests
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