The water content of the soils was adjusted to 21% for all soils. Due to differences in water holding capacity (WHC) this corresponds to 50e62% of WHC. The soils were pre-incubated moist and aerated at room temperature in the dark for three weeks before an incubation experiment was initiated. From each plot, 3 replicate samples of 100 g DW were made in small plastic cups and these were put in an airtight jar. A beaker with water was placed in each jar to maintain soil moisture. Six empty jars served as blanks. All jars were incubated at 25 C in the dark. Respiration was measured 5 times during the incubation experiment on day 0e4, 4e8, 8e15, 15e18 and 62e64, by determining trapped CO2eC in vials with 0.5 M NaOH placed in the jars. NaOH traps were analyzed by backtitration using HCl with BaCl2 added and phenolphthalein as indicator. CO2eC production was calculated from the difference in ml HCl use between blanks and treatments (Anderson and Ingram, 1993). Being collected in late winter, the soils had not been amended with organic matter for almost one year, and thus the cumulative