中文摘要：

于2008年4月～2009年4月在龙王山北亚热带落叶阔叶林地进行模拟氮沉降试验,利用静态箱-气相色谱法测定土壤呼吸,研究氮沉降增加对森林土壤呼吸的影响.结果表明,氮沉降没改变土壤呼吸的季节性变化规律和日变化规律.与对照（CK）相比,低氮（TL）、中氮（TM）和高氮（TH）处理使森林土壤年平均呼吸速率分别降低了8.51%、9.74%和11.24%,使日平均呼吸速率分别降低了4.42%、11.09%和12.17%.森林土壤呼吸与土壤温度存在极显著的指数关系（p〈0.01）,CK、TL、TM和TH的土壤呼吸温度敏感系数（Q10）分别为2.53、3.22、2.64和2.92,氮沉降提高了林地土壤呼吸的温度敏感系数.本研究表明,氮沉降显著降低了森林土壤呼吸,但提高了土壤呼吸的温度敏感性.

英文摘要：

To investigate the effects of elevated nitrogen deposition on forest soil respiration,a simulated nitrogen deposition field experiment was conducted in northern subtropical deciduous broad-leave forest from April 2008 to April 2009.Nitrogen treatments included the control（no N addition,CK）,low-N [50 kg.（hm^2·a）^-1,TL ],medium-N [100 kg·（hm^2·a）^-1,TM ],and high-N [150 kg·（hm^2·a）^-1,TH].The respiration rates were measured by a static chamber-gas chromatograph method.Results showed that nitrogen deposition did not change the seasonal and daily variation patterns of soil respiration.Compared to the control,TL,TM and TH treatments reduced soil annual average respiration rates by 8.51%,9.74% and 11.24%,respectively.Meanwhile,TL,TM and TH treatments decreased daily average soil respiration rates by 4.42%,11.09% and 12.17%,respectively.Significant relationship was found between soil respiration rate and soil temperature.The Q10（temperature sensitivity coefficients） for soil respiration of CK,TL,TM and TH treatments were 2.53,3.22,2.64 and 2.92,respectively.Our findings suggested that nitrogen deposition reduced soil respiration,and increased soil respiration temperature sensitivity in northern subtropical deciduous broad-leave forest.