缙云山常绿阔叶林土壤呼吸对模拟氮沉降的响应

Responses of Soil Respiration to Simulated Nitrogen Deposition in an Evergreen Broad-Leaved Forest in Jinyun Mountain

通过原位喷施,设置对照(CK,0 kgN·hm-2a-1)、低氮(T50,50 kgN·hm-2a-1)、中氮(T100,100 kgN·hm-2a-1)和高氮(T150,150 kgN·hm-2a-1)4个氮沉降处理,研究重庆缙云山常绿阔叶林土壤呼吸对模拟氮沉降的响应。结果表明:CK,T50,T100和T150氮沉降处理的土壤呼吸速率分别为(4.31±1.14),(3.42±0.74),(2.81±0.38)和(2.49±0.32)μmol·m-2s-1,相对于CK处理,氮沉降处理使土壤呼吸速率显著降低(P<0.05);土壤呼吸速率与5和10 cm深处土壤温度间均存在显著指数正相关关系(P<0.01);4个处理5 cm深处的土壤呼吸温度敏感系数Q10值分别为2.07,1.81,1.62和1.54,10 cm深处的Q10值分别为2.11,1.83,1.63和1.55,氮沉降处理抑制了土壤呼吸温度敏感性;土壤呼吸速率与土壤含水量之间相关性较弱。

The responses of soil respiration to simulated nitrogen deposition were investigated through in-suit spray with four rising nitrogen concentration levels：control （CK,0 kgN · hm-2a-1）,low nitrogen （T50,50 kgN · hm-2a-1）,medium nitrogen （T100,100 kgN · hm-2a-1） and high nitrogen （T150,150 kgN · hm-2a-1）.This study was conducted in an evergreen broad-leaved forest in Jinyun mountain,Chongqing City.Results showed that the CK,T50,T100 and soil respiration rates were（4.31 ± 1.14）,（3.42 ±0.74）,（2.81 ±0.38） and （2.49 ±0.32） μmol · m-2s-1,respectively,indicating that nitrogen deposition treatments significantly reduced soil respiration rates （P 〈 0.05）.The relationships between soil respiration rates under different nitrogen treatments and soil temperature,and water contents at depths of 5 and 10 cm were analyzed.A remarkable positive correlation was found between soil respiration rates and soil temperature （P 〈 0.01）.The temperature sensitivity coefficients（Q10 value） at 5 cm depth were 2.07 （CK）,1.81 （T50）,1.62 （T50）and 1.54（T50） respectively,and at 10 cm depth were 2.11 （CK）,1.83 （T50）,21.63 （T100） and 1.55 （T150） respectively,which demonstrated that the sensitivity of soil respiration to soil temperature was restrained by nitrogen deposition.However,there was no obvious correlation between soil respiration rate and soil moisture.