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