Evaluating the impacts of incubation procedures on estimated Q(10) values of soil respiration

摘要

A reliable determination of the response of soil organic carbon decomposition to temperature is critical in the context of global warming. However, uncertainties remain in estimated temperature sensitivity of soil respiration, which may be partly due to different experimental conditions. To investigate the possible effects of laboratory incubation procedures on estimated Q(10) value, soil samples taken from various ecosystems were incubated under changing temperature with different experimental conditions or procedures: 1) different rate of temperature change; 2) different intervals of temperature change; 3) equilibration time after temperature change; 4) the duration of chamber closure and 5) the size of incubated soil sample. The results indicated that respiration rate was affected by experimental procedures. The respiration rate of soil samples containing high concentration of organic carbon decreased quickly if the soil container sealed longer than 2 h. Estimated Q(10) values across all soils ranged from 1.56 to 2.70, with respect to the effects of incubation procedures. Temperature rate change, equilibration time, the duration of chamber closure and soil sample size had no effect on estimated Q(10) values of soil respiration. However. Q(10) values derived from temperature changing intervals of 2 and 7 degrees C were significantly different, despite the fact that the exponential function fitted well for the relationship between respiration rate and temperature for both intervals. The results of these experiments suggested that incubation procedures have different effects on measured soil respiration and estimated Q(10) values. For soil incubations of short-duration, the effects of incubation procedures on soil respiration and estimated Q(10) values based on respiration rate should be appropriately tested with experimental setting-up, and estimating Q(10) values with few temperatures should be avoided.