Nitrogen and phosphorus availability in eastern Manitoba black spruce bog ecosystems 10 years after clearcut logging and wildfire

Abstract

Recent interest by the forestry industry in establishing clearcut logging practices which emulate the effect of natural disturbances, such as wildfire on site productivity, has sparked an increase in comparative studies between anthropogenic and natural disturbances. The objectives of this study were to determine nitrogen and phosphorus availability differences after 10 years between black spruce bog ecosystems affected by either clearcut logging or natural wildfires. This was accomplished by focusing on: (1) differences in the spatial heterogeneity of inorganic N and P concentrations; (2) spatial heterogeneity of nitrogen mineralisation; (3) peat substrate quality differences; and (4) relationships between peat substrate quality and net N/P mineralisation. Three-way analysis of variance, incorporating spatial factors, exhibited significant differences in inorganic N concentrations between disturbance types with mature stands greater than clearcut sites and burn sites. A two month in situ incubation was performed to measure net nitrogen mineralisation. Carbon fraction analysis indicated that disturbance typed differed with respect to various substrate quality parameters. (Abstract shortened by UMI.)