季节性休牧对草甸草原放牧系统甲烷通量的影响

Effects of Seasonal-resting on Methane Fluxes in the Grazing System in Meadow Steppe

甲烷(CH_(4))是1种主要的温室气体。为了探究温性草甸草原放牧系统的CH_(4)通量特征,本研究设置了围封(CK)、持续放牧(CG)、早期休牧(R1)、中期休牧(R2)以及晚期休牧(R3)等多个处理,通过监测放牧季的土壤CH_(4)通量并测定放牧绵羊的CH_(4)排放量,计算了草地土壤的CH_(4)“碳汇”贡献度。结果表明:草地土壤在不同日期吸收CH_(4)的通量范围是25.37~79.46μg·m^(-2)·h^(-1),吸收值在不同处理之间差异极显著(P<0.001),且CG,R1,R2和R3处理均高于CK处理;放牧绵羊的CH_(4)排放量在R3处理中最高而在R2处理中最低(P<0.001);草地土壤吸收CH_(4)-C的贡献度在不同处理之间也具有极显著的差异(P<0.001),CG处理最高而R1处理最低。综上所述,季节性休牧既可以增加草地土壤对CH_(4)的吸收,也会减少绵羊的CH_(4)排放量,适度的持续放牧和中期休牧处理是适合当地的草地放牧管理方式。

Methane(CH_(4))is a major greenhouse gas.In order to explore the characteristics of CH_(4)fluxes in the grazing system in temperate meadow steppe,we set five grazing treatments as:enclosed(CK),continuous grazing(CG),early-resting(R1),mid-resting(R2)and late-resting(R3),and monitoring soil CH_(4)fluxes during the grazing season and measuring the CH_(4)emissions from the sheep grazed in the grazing treatments,respectively;the contribution of grassland soil about the CH_(4)“carbon sink”was also calculated.The results showed that the fluxes of CH_(4)absorbed by grassland soil on different date ranged from 25.37 to 79.46μg·m^(-2)·h^(-1),the uptake values of CH_(4)by grassland soil were highly significant(P<0.001)among treatments with a higher in CG,R1,R2 and R3 grazing treatments than that in CK;the grazing sheep in R3 emitted the highest CH4 and those in R2 emitted the lowest(P<0.001).The CH_(4)-C“carbon sink”contribution of grassland soil was also significantly different between among different grazing treatments(P<0.001),and it was the highest in CG and the lowest in R1.In conclusion,seasonal-resting could not only increase the CH_(4)absorption of grassland soil,but also reduce the CH_(4)emissions of sheep,moderate continuous grazing and mid-resting are suitable for local grassland grazing management.