Canadian Forest Service Publications

Heterogeneity in soil nitrogen within first-order forested catchments at the Turkey Lakes Watershed. 2005. Foster, N.W.; Spoelstra, J.; Hazlett, P.W.; Schiff, S.L.; Beall, F.D.; Creed, I.F.; David, C. Canadian Journal of Forest Research 35: 797-805.

Year: 2005

Available from: Great Lakes Forestry Centre

Catalog ID: 28184

Language: English

CFS Availability: PDF (request by e-mail)

Abstract

Topographic positional regulation of nitrogen (N) dynamics in soil within Canadian Shield headwaters, located in calibrated catchments containing mature, tolerant hardwood forest, was examined to determine how N pools, mineralization, nitrification, and leaching in soil relate to N export in drainage waters. A uniformly high net N mineralization and nitrification potential for surficial soil layers rich in organic N was demonstrated for ridge, upper-middle slope, and lower slope – footslope topographic positions. Results from plot-scale studies revealed that NO3– concentrations in soil water from well-drained soils were very highly variable throughout the catchments, ranging from 25 to 175 µmol·L–1, with a median of 80 µmol·L–1. The isotopic effects of denitrification were not detected in soil water collected from lower slope – footslopes, and in situ rates of N2O production from soils on lower slope – footslopes and valley bottoms were very low and highly variable. Higher N exports from soils than from streams were not explained by differences in soil water N with topographic position or denitrification in lower landscape topographic positions. Using an average soil water N value, based on the replicated plots within catchments, did not reduce the calculated substantial differences in N export between soils and streams.