Canadian Forest Service Publications

A geospatial and temporal framework for modeling gaseous N and other N losses from forest soils and basins, with application to the Turkey Lakes Watershed Project, in Ontario, Canada. 2009. Murphy, P.N.C.; Castonguay, M.; Ogilvie, J.; Nasr, M.; Hazlett, P.W.; Bhatti, J.S.; Arp, P.A. Forest Ecology and Management 258(10): 2304-2317.

Year: 2009

Available from: Northern Forestry Centre

Catalog ID: 30278

Language: English

CFS Availability: Order paper copy (free), PDF (request by e-mail)

Abstract

This article quantifies pre- to post-harvest gaseous N emissions and other N losses from forest soils and basins geospatially and temporally via digital elevation and hydrological modeling, using daily rain, snow and air temperature records, annual atmospheric N deposition rates, and basin-specific soil and forest specifications as input. The approach relates gaseous N losses from soils to soil temperature and water-filled pore space (WFPS) as affected by the depth-to-water (DTW) below the soil surface. The approach is applied to the Turkey Lakes Watershed Project (TLW) in Ontario, 60 km north of Sault St. Marie, where basin-wide N losses due to denitrification would mostly be restricted to the wetland portions of the basin. Basin-wide N losses via denitrification and stream export (mineral N and dissolved organic N) were empirically related to upland N mineralization and soil leaching as controlling processes. The calibrated model calculations, set to conform to the field-monitored N concentrations in TLW streams, suggest that the harvest-induced nitrification and denitrification pulses would be strongest near the end of the first post-harvest year, dropping to background levels within about 4–5 years later. The article concludes with assessing basin-specific denitrification efficiencies in relation to atmospheric N deposition and basin-to-basin wetland coverage.

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