Nitrogen export from a watershed subjected to partial salvage logging.

Maria Herrmann,William E Sharpe,Bryan R Swistock,David R Dewalle

doi:10.1100/tsw.2001.290

Maria Herrmann, William E Sharpe + Show 2 more

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https://doi.org/10.1100/tsw.2001.290

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Journal: TheScientificWorldJournal	Publication Date: Jan 1, 2001
Citations: 6	License type: CC BY 3.0

Affiliation: Pennsylvania State University

Abstract

Logging has been shown to induce nitrogen (N) leaching. We hypothesized that logging a watershed that previously exhibited forest decline symptoms would place additional stress on the ecosystem and result in greater N loss, compared to harvesting vigorous forests. We conducted a 10-year (1988 to 1998) assessment of N export from the Baldwin Creek watershed in southwestern Pennsylvania that was partially clearcut to salvage dead and dying northern red oak. N export from the watershed increased significantly following salvage logging operations and did not completely return to prelogging levels by the end of the study period. The largest annual NO3-N export of 13 kg/ha was observed during the first year after harvesting, an increase of approximately 10 kg/ha. Compared to data from other Appalachian Mountain watersheds in North Carolina, West Virginia, and Pennsylvania, calculated N loss for Baldwin Creek was considerably greater. Longer periods of reduced N uptake due to slow revegetation of salvage logged areas, coupled with increased amounts of N available to leaching, could have accounted for the large N losses observed for Baldwin Creek. Salvage logging of dead and dying trees from forested watersheds in this region appears to have the potential to result in much larger N losses than previously reported for harvest of healthy stands.

Highlights

The effects of forest harvesting on water quality have been studied extensively since the 1970s, with nitrogen (N) often exhibiting the most significant responses to disturbance compared to other nutrients[1,2,3,4]
The objective of this research was to assess N export from the Baldwin Creek watershed in southwestern Pennsylvania, which was partially salvage logged to recover dead and dying hardwoods, primarily northern red oak (Quercus rubra)
We hypothesized that significant increases in N export would occur following the disturbance on the Baldwin Creek watershed and that salvage logging would induce greater N losses, compared to clearcut watersheds with essentially healthy vegetation at the time of harvest

Summary

Introduction

The effects of forest harvesting on water quality have been studied extensively since the 1970s, with nitrogen (N) often exhibiting the most significant responses to disturbance compared to other nutrients[1,2,3,4]. Harvesting causes reduced N uptake and increased soil temperature and moisture that result in higher mineralization and nitrification rates[2,4,5]. These changes in N dynamics often cause increased nitrate (NO3) leaching below the rooting zone and increased NO3 concentrations in streams. Durka and colleagues[6] assessed NO3 leaching in stream water from declining and nondeclining sites. They found that 16 to 30% of stream water NO3 in healthy or slightly declining stands originated directly from the atmosphere, while on more severely declining sites atmospherically deposited NO3 was much higher. Both net N mineralization and nitrification were significantly higher at the harvested plots that had N additions

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