Peroxidase activity was calculated as the difference between samples reactedwith and without H2O2 (Sinsabaugh et al., 1993). Units for phenol oxidase and peroxidase are in absorbance units h21 g21 dry soil. All other enzyme activities were expressed as mmol substrate converted h21 g21 dry soil. The specific activities of the enzymes were calculated by dividing total enzyme activities by the microbial biomass C determined by CFDE.