DYNAMICS OF THE MICROBIAL RESPIRATION ACTIVITY IN SAMPLES FROM A RAISED BOG AND NEARBY AUTOMORPHIC SOIL

The dynamics of respiration activity (RA) were analyzed and compared i n samples of peat from a raised bog and automorphic podzolic soil incu bated under laboratory conditions at a constant temperature and humidi ty. RA was found to fall off as the reciprocal of time, which reflects a depletion of the pool of oxidizable substrates available to microor ganisms. By fitting a simple two-compartment model to the obtained cur ves, the fraction of organic compounds available to bacterial oxidatio n was found to be as low as 0.3-0.6% of the total organic matter conte nt in peat and 4% in automorphic soil. No qualitative changes in RA dy namics in peat were observed when the incubation temperature was raise d from 25 to 38 degrees C; however, the RA values were higher at the b eginning of the experiments at 38 degrees C, and this can be formally explained by an increase in the amount of oxidizable substrates. Their source could possibly be dead cells of microbial populations eliminat ed in the early period of rearrangement of the bacterial community in response to the change in temperature.