Effects of forest clear-cutting on the carbon and nitrogen fluxes through podzolic soil horizons |
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Authors: | Piirainen Sirpa Finér Leena Mannerkoski Hannu Starr Michael |
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Institution: | (1) The Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland;(2) University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland;(3) The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland |
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Abstract: | Effects of clear-cutting on the dissolved fluxes of organic C (DOC), organic N (DON), NO3
– and NH4
+ through surface soil horizons were studied in a Norway spruce dominated mixed boreal forest in eastern Finland. Bulk deposition, total throughfall and soil water from below the organic (including understorey vegetation and, after clear-cutting, also logging residues), eluvial and illuvial horizons were sampled weekly from 1993 to 1999. Clear-cutting was carried out in September 1996. The removal of the tree canopy decreased the deposition of DOC and DON to the forest floor and increased that of NH4
+ and NO3
– but did not affect the deposition of total N (DTN, <3 kg ha–1 a–1). The leaching of DOC and DON from the organic horizon increased over twofold after clear-cutting (fluxes were on an average 168 kg C and 3.3 kg N ha–1 a–1), but the increased outputs were effectively retained in the surface mineral soil horizons. Inorganic N deposition was mainly retained by the logging residues and organic horizon indicating microbial immobilization. Increased NO3
– formation reflected as elevated concentrations in the percolate from below the mineral soil horizons were observed especially in the third year after clear-cutting. However, the changes were small and the increased leaching of DTN from below the illuvial horizon remained small (<0.4 kg ha–1 a–1) and mainly DON. Effects of clear-cutting on the transport of C and N to surface waters will probably be negligible. |
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Keywords: | ammonium deposition DOC DON harvesting lysimeter nitrate percolate |
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