NITRIFICATION AND DENITRIFICATION IN A WHITE SPRUCE FOREST IN SOUTHWEST ALBERTA, CANADA

Nitrification and denitrification were measured in a 120-year-old Picea glauca (Moench) Voss forest in southwestern Alberta. Nitrifying activity could not be detected using short-term incubations of F-H and upper mineral soil horizons. Long-term incubations for nitrifying potential indicated that nitrifying organisms were present. The results suggest that the population of nitrifying organisms must have been small, their activity was limited, or the microhabitat necessary, for their activity was not adequately simulated by the soil slurries in the short-term incubations. Low rates of denitrification were detected but probably did not represent a substantial loss of N from the soil-plant system. Low rates of denitrification may have been due to a lack of substrate (NO3-), reflecting the low rates of nitrification.