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研究土壤垂直剖面CO_2通量的分布是了解生态系统碳循环的重要环节.本研究以亚热带杉木幼林为研究对象,于2014年5月至2015年5月,采用气井法结合Fick扩散法则和扩散系数模型计算15、30、60 cm各层土壤的CO_2通量,探讨增温对其影响.结果表明:杉木幼林土壤增温影响可至60 cm土层,增温显著降低了各层土壤含水量(p<0.05).增温显著增加了杉木幼林土壤CO_2通量(p<0.05),深层尤为显著;增温处理(W)后15、30、60 cm土层的土壤CO_2通量年均值分别为1.35、0.73和0.36μmol·m-2·s-1,比对照(CT)相应增加了36%、180%和192%,并且增温显著影响了土壤基础呼吸速率F10和土壤温度敏感性指数Q10(p<0.05).土壤温度和含水量能够共同解释各层土壤CO_2通量季节变异的62%~87%,且增温处理后其R2增大.双因子模型拟合结果优于单因子模型.增温能够增加土壤呼吸,对全球大气CO_2浓度升高具有正反馈作用.
Studying the distribution of CO_2 fluxes in the vertical section of soil is an important step in understanding the carbon cycle of ecosystems.Taking the subtropical Chinese fir young forest as the research object from May 2014 to May 2015, this study adopted gas well method combined with Fick diffusion law and diffusion coefficient The CO_2 fluxes of 15, 30, 60 cm soil layers were calculated to study the effects of warming on the soil temperature.The results showed that the soil temperature of 60 cm soil layer influenced the warming of young Chinese fir plantations, (P <0.05) .Increased temperature significantly increased soil CO2 fluxes (P <0.05), especially in the deep layer of the young Chinese fir plantations. The average values of soil CO_2 fluxes in 15, 30 and 60 cm soil layers after warming (W) 1.35, 0.73 and 0.36μmol · m-2 · s-1, which increased by 36%, 180% and 192% respectively compared with the control (CT), and the soil respiration rate F10 and soil temperature sensitivity index Q10 (p <0.05) .The soil temperature and water content can explain 62% -87% of the seasonal variation of soil CO_2 fluxes in all layers, and R2 increased after warming treatment.The fitting results of two-factor model were better than the single factor model Warming can increase soil respiration, which has positive feedback on the increase of global atmospheric CO 2 concentration.