The growth of fungi and bacteria were uncoupled from the initial pulse in respiration induced by rewetting dry soil. In both the 4-days and 1-year dried soils, the respiration pulse started immediately at higher rates than in the constantly moist control, whereas both fungal and bacterial growth started from low values and then increased. This was earlier found for bacterial growth (Iovieno and Bååth, 2008; Göransson et al., 2013), but we are here also able to
demonstrate that fungal growth cannot explain the initial rapid response in respiration after rewetting. In addition, we find no support that fungal growth explains the exponential increase in respiration that occurred 16 h after rewetting the 1-year dried soil. Instead the exponential increase in respiration followed a similar pattern as the increase in bacterial growth. The duration of the lag period was the same for bacterial growth and respiration, and the subsequent rates of increase (mresp and mbact) were also similar. Furthermore, mresp after rewetting was within the range of mresp calculated from the respiration responses induced by exponential microbial growth after adding glucose (0.14e0.41 h1, Anderson and Martens, 2013); growth responses that are assumed to be mainly due to bacteria. Taken together, this suggests that bacterial growth explained the observed respiration response during this period of exponential increase in respiration in 1-year dried soil.
The growth of fungi and bacteria were uncoupled from the initial pulse in respiration induced by rewetting dry soil. In both the 4-days and 1-year dried soils, the respiration pulse started immediately at higher rates than in the constantly moist control, whereas both fungal and bacterial growth started from low values and then increased. This was earlier found for bacterial growth (Iovieno and Bååth, 2008; Göransson et al., 2013), but we are here also able todemonstrate that fungal growth cannot explain the initial rapid response in respiration after rewetting. In addition, we find no support that fungal growth explains the exponential increase in respiration that occurred 16 h after rewetting the 1-year dried soil. Instead the exponential increase in respiration followed a similar pattern as the increase in bacterial growth. The duration of the lag period was the same for bacterial growth and respiration, and the subsequent rates of increase (mresp and mbact) were also similar. Furthermore, mresp after rewetting was within the range of mresp calculated from the respiration responses induced by exponential microbial growth after adding glucose (0.14e0.41 h1, Anderson and Martens, 2013); growth responses that are assumed to be mainly due to bacteria. Taken together, this suggests that bacterial growth explained the observed respiration response during this period of exponential increase in respiration in 1-year dried soil.
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