Our results suggest that forest type could have an important influence on microbial enzyme activities in these soils, and the response of enzyme activities to changes in nutrient availability. For instance, although extant soil AP activities were typically lower in the treated WB watershed compared with the reference EB watershed (Fig. 1, Table 2), our analysis of extractable PO4-P in these soils (Table 2) demonstrated that PO4-P was higher in the Nenriched WB compared with reference EB only in the O horizons of hardwoods; this difference was not apparent between the watersheds
in softwood stands. We hypothesize that the lower extant AP activities in the N-enriched watershed more likely reflects a general suppression of microbial biomass and activity, and not changes in
the rate of microbial acquisition of P via AP activity.
PO4eP concentrations we observed in the N-enriched hardwood
soils compared with reference hardwood soils could be attributable
to a stimulation of nutrient cycling due to N-enrichment in the WB
watershed.